Food as Medicine: Chia (Salvia hispanica, Lamiaceae)

Chia (Salvia hispanica, Lamiaceae) is an annual herb native to Mexico and Guatemala that requires fertile, well-drained soil and subtropical climate conditions to set seed in the late summer months of July and August.1-4 Chia is the most common name for this plant, but it is also sometimes called Spanish sage, lime-leaf sage, Mexican chia, and black chia.2,4 The plant grows to three feet (0.9 meters) tall when mature, and has opposite, serrated leaves that are 1.5-3 inches (3.8-7.6 cm) long and 1-2 inches (2.5-5 cm) wide, and produces small white or purple flowers on the tips of its terminal stems.2,4,5 Chia’s leaves contain essential oil that acts as a defense mechanism to repel insects.2 The edible part of the chia plant is the seeds,5-7which are small (2 mm in length), flat, and oval-shaped.2 Although dark chia seeds are predominantly gray with dark spots,7 they can also appear white, black, black spotted, or dark brown, and may differ slightly in size and weight.2,5

Phytochemicals and Constituents

Chia seed has high levels of protein, omega-3 fatty acids, fiber, and specific vitamins and minerals.2,7 The seed also contains all essential amino acids and is high in antioxidants.8 A gram of chia seeds contains about 0.28 g fiber, 0.21 g protein, and 0.6 g/g of the omega-3 fatty acid alpha-linolenic acid (ALA), which is the highest proportion of ALA of any known plant source.9 Chia seed and its oil have an abundance of polyunsaturated fatty acids (PUFAs). ALA is the most predominant fatty acid found in chia, followed by the omega-6 fatty acids linoleic acid and oleic acid.

Omega-6 fatty acids have pro-inflammatory, hypertensive, and prothrombotic properties.5Omega-3 fatty acids, however, are associated with numerous health benefits and have anti-inflammatory, anti-diabetic, lipid-lowering, cardioprotective, and hepatoprotective properties. For maintenance of good health, omega-3 fatty acids should be incorporated in the diet at higher amounts than omega-6 fatty acids. The omega-3:omega-6 ratio found in chia seeds is about 3:1.6,7 The amount of oil within chia seed ranges from 25-40%.2,5

In comparable serving sizes, the protein content of chia seeds exceeds that of seeds such as amaranth (Amaranthus spp., Amaranthaceae) and quinoa (Chenopodium quinoa, Chenopodiaceae).2 The primary determinant of a high-quality protein is its digestibility or the amount of protein absorbed by the body relative to the amount consumed. For chia seed flour, protein digestibility is nearly 80%, which is comparable to processed cereal grains such as wheat (Triticum aestivum, Poaceae) and oats (Avena sativa, Poaceae); however, chia contains a much higher percentage of protein per serving than these grains.10Furthermore, chia seed contains high levels of the amino acids glutamic acid, arginine, and aspartic acid.2In addition to an abundance of these non-essential amino acids, chia seed contains all nine essential amino acids that the body is unable to produce and is therefore considered a complete protein, unlike other plant protein sources such as chickpeas (Cicer arietinum, Fabaceae). Chia seed contains low concentrations of prolamins (< 15%), which suggests that it can be safely incorporated into the diet of patients with celiac disease.2,10

Approximately two tablespoons (one ounce or about 28 grams) of chia seed provides almost 40% of an average person’s daily fiber intake, as recommended by the US Food and Drug Administration (FDA). Total dietary fiber includes both soluble and insoluble forms that are important for reducing the risk of cardiovascular disease, diabetes, and certain types of cancer.2 Compared to other foods, chia seed contains more dietary fiber than an equivalent volume of flax (Linum usitatissimum, Linaceae) seed. High fiber intake also promotes gastrointestinal and digestive health.

Chia seeds and oil are not only known for their macronutrient and micronutrient contents, but also for their antioxidant properties.7 Phenolic compounds present in chia have been found to protect against certain diseases, such as cardiovascular disease and diabetes.11 The most important polyphenols found in chia seeds and seed oil include chlorogenic and caffeic acids, which play a crucial role in the protection against free radicals and inhibit fat, protein, and DNA peroxidation.2,11,12 The flavonols myricetin, quercetin, and kaempferol are other active compounds present in chia seeds.7 Flavonols are known for their antioxidant, cytotoxic, anti-inflammatory, and anti-thrombotic effects.5,13 Researchers have found that these polyphenols and others found in chia seed and seed oil (e.g., rosmarinic, protocatechuic, and gallic acids) have a high antioxidant capacity.12,14

Historical and Commercial Uses

Chia has been used by Mesoamerican cultures for more than 1,000 years for medicinal, culinary, artistic, and religious purposes.7,15 The Chumash and Cahuilla peoples in the coastal southern regions of California cultivated chia for its seeds, which were collected, hulled, and winnowed by hand.16 After the introduction of wheat, chia was still a preferred crop, and small amounts of chia flour were used to improve the flavor of wheat flour.

The seed of the chia plant is the part most often used for medicinal purposes, but the root and aerial parts were also used occasionally.15 Prior to Spanish colonization in the 16th century, chia seed was used by native tribes to provide energy, treat respiratory infections, and for obstetrics treatment. Prized by Aztec warriors in central Mexico, chia seeds were eaten to promote endurance and consumed with bread prior to battle or with water before running long distances.8

The Diegueño people of Baja California took chia seeds on journeys, kept a few seeds in the mouth and periodically chewed them to maintain their strength.16 One tablespoon of chia seed was believed to be sufficient to feed a person for a day. After the 16th century, a mucilaginous paste made from chia seeds and water was used therapeutically to treat eye obstructions and infections.17 Medical uses of chia seed prior to Spanish colonization included soothing skin conditions, treating gastrointestinal conditions, lowering fevers, and as a poultice for open wounds.15,16

The chia seed has been used for culinary purposes in multiple forms: whole, ground (flour), mucilage, and oil.7,15 Seeds were ground into flour and used to make biscuits, cakes, and a porridge called pinole.16 Traditional foods, such as tortillas and tamales, were made from chianpinolli, or roasted and ground chia seed.15,17 Chia flour was used to make an array of beverages during the height of the Aztec Empire, but modern use of this tradition has declined.15 The most recognized use of chia seeds in the 18th and 19th centuries was infusing chia seeds in water, which was believed to make the alkaline desert water taste more palatable. “Chia fresca,” or “agua de Chia,” was also a popular, thirst-quenching beverage that combined chia seeds with fruit juices.15-17

Chia seed oil was also used for artistic purposes, primarily in paints and lacquers to create a glossy finish on clay or gourd vessels.15 The oil was also used as the basic ingredient for ceremonial face or body paint. Chia-infused beverages were historically consumed during ceremonies, festive occasions, and holy observances. Other religious uses included the use of chia flour to make dough that was formed into the shape of the goddess Chicomecoatl, the “maker and giver of things necessary to live,” as an offering. With the rediscovery of chia as an important food source, modern uses of chia seed and oil focus on its omega-3 fatty acid content for nutritional supplementation, and it is sold commercially as cold-pressed seed oil or whole seeds as ingredients for baked goods, snacks, bread, yogurt, and bars.2

In 1977, the Chia Pet, small hollow-bodied animal figurines made out of terra cotta, became a registered trademark of Joseph Enterprises, Inc.18 Moistened chia seeds are applied to the grooved ridges on the outside of the figurine, and water is added to the hole inside the figurine to help the seeds germinate. Within days, the figure grows a thick coat of chia sprouts. For more than 30 years, Chia Pets have offered customers amusement and an introductory lesson to the practice of cultivating plants.

Modern Research

Cardiovascular Disease Risk Factors

The nutrient profile and bioactive compounds found in chia seed and oil have demonstrated cardioprotective effects by reducing disease risk factors in humans. Hypertension, a known risk factor for developing cardiovascular disease, is generally asymptomatic and can be difficult to control with drug therapies alone. Diet interventions can offer a complementary approach.19 Supplementation with ground chia seed for 12 weeks was shown to reduce blood pressure in individuals with treated and untreated hypertension. Participants in the study were randomly assigned to one of three groups: consumption of chia with previously used medications (CHIA-MD), chia without medications (CHIA-NM), or a placebo group with medications (PLA-MD). Subjects in the two treatment groups consumed 35 grams of chia flour per day. The PLA-MD group received 35 grams of roasted wheat bran as a placebo. Researchers found that the two chia groups had significantly reduced diastolic and systolic blood pressures from baseline. The CHIA-MD group also had significantly reduced total blood pressure from baseline.

A 2015 systematic review investigated current literature on consumption of whole or ground chia seeds and its effect on preventing or managing risk factors associated with heart disease, such as hypertension, diabetes, dyslipidemia, and obesity.20 The review focused on seven clinical trials published between 2007 and 2013. The chia seed preparations used in the studies varied in quantity (4-50 grams per day) and type (e.g., whole or milled). There were also differences in sample size, methodology, and participant characteristics (e.g., diabetic, obese, hypertensive). Therefore, the authors state that the findings on chia consumption and the effects of reducing cardiovascular risk factors are inconclusive. They recommend additional randomized, double-blind, placebo-controlled clinical trials on the consumption of chia to obtain reliable results and to determine an appropriate dose for cardioprotective benefits.

Obesity is a condition that has been associated with a state of chronic oxidative stress. Reactive oxygen species damage cell proteins, lipids, and DNA, and can result in impaired function and potentially cell death. Obesity also impedes the body’s enzymatic antioxidant system, reducing the activities of catalase, superoxide dismutase, glutathione peroxidase, and glutathione reductase.24 Additionally, obesity correlates with a reduction in levels of protective thiols, vitamins, minerals, and polyphenols. A study on chia seed’s efficacy for weight loss and decreasing disease risk factors in overweight adults found increases in plasma ALA levels. However, consumption of chia seed in high doses (50 grams per day) had no effect on weight loss or changes in disease risk factors related to cardiovascular disease (e.g., blood pressure, high-density and low-density lipoprotein, total cholesterol, or blood triglyceride levels).21Another randomized, double-blind, placebo-controlled study assessed the effectiveness of chia seed (whole or ground) supplementation for changing disease risk factors for overweight women.22 For 10 weeks, participants consumed 25 grams per day of ground or whole chia seeds or a placebo. Multiple outcome measures were assessed, and researchers observed a 58% and 39% increase in plasma ALA and eicosapentaenoic acid (EPA) levels, respectively, in the ground chia treatment group.

Glucose Levels

The use of chia as a food ingredient holds promise in the area of so-called “functional foods.” A 2013 study observed the effects of bread supplemented with chia seed flour on post-prandial (after-meal) blood sugar levels in healthy adults. Thirteen healthy adults consumed nine test meals that included bread supplemented with different doses (seven, 15, and 24 grams) of whole or ground chia.23 Bread without chia was used as the control. Researchers concluded there was a significant dose-dependent effect on blood glucose levels for both whole and ground seeds compared to the control, but no differences were evident between the same doses of the whole and ground seed groups. This may indicate that the quantity of seeds given in the diet will demonstrate hypoglycemic properties and not the form in which chia is ingested. The seeds used in the study were a specific varietal bred from black chia and proved effective for reducing blood glucose levels, but future research is needed to further investigate the benefits of different chia strains.

Antioxidant Properties

Chia’s antioxidant potential was analyzed in a 2015 rat study.24 Results demonstrated that daily consumption of chia seed and chia seed oil enhanced plasma antioxidant levels through catalase, glutathione peroxidase and thiol level reduction. Chia seed and seed oil intake resulted in a significant reduction in plasma levels of 8-isoprostane, the most specific biological indicator for assessing oxidative stress in vivo. High levels of 8-isoprostane can occur with a diet high in fat and fructose and result in pro-oxidative effects. This may be the mechanism by which chia seed and seed oil produce a hypolipidemic effect. Lipid peroxidation in rat livers was not reversible; however, levels of glutathione reductase were increased as well as thiol levels, resulting in improved antioxidant status.

Other Uses

Carbohydrate-loading refers to the practice of increasing dietary intake of carbohydrates prior to athletic events that last more than 90 minutes. This intake results in a greater capacity of muscle glycogen stores and aids in improved athletic performance.8 A 2011 study compared performance test results of six male marathon runners who were given two different carbohydrate-loading treatments: a commercial sports drink and the same commercial sports drink supplemented with chia. The runners participated in two trials in a crossover, counterbalanced, repeated-measure design with a two-week washout period between testing to allow participants to recover from the intense exercise and to avoid any carry-over effects from the treatments. While the researchers found no statistical difference between the control and the test groups in performance parameters, the athletes in the chia group significantly decreased their dietary intake of sugar while boosting intake of omega-3 fatty acids, which indicates that the chia drink may be a healthier option for athletes who choose to carbohydrate-load.

Chia seed oil is also used topically. Approximately 30% of patients with diabetes or end-stage renal disease (ESRD) suffer from skin disorders including pruritus, which is characterized by itchy, dry skin and inflammatory lesions caused by scratching.13 This study followed five patients with these conditions (three with diabetes; two with ESRD) and five patients without these conditions who all exhibited xerotic pruritus (abnormally dry, itchy skin) for eight weeks. A topical oil and water emulsion containing 4% chia seed oil were applied to the affected skin. Lotion without chia seed oil was used on participants as a placebo. After eight weeks of application, statistically significant improvements in skin hydration, chronic itching, and prurigo nodularis (hard, itchy lumps on the skin) were observed in the treatment group with diabetes and ESRD, while similar significant improvements in skin hydration and epidermal permeability were also observed in the group of patients without these conditions.

Consumer Considerations

Consumption of whole or ground chia seed has shown no evidence of toxicity or allergenic effects.2However, the Dietary Guidelines for Americans, eighth edition, issued by the US Department of Health and Human Services and US Department of Agriculture listed a standard portion size of chia as one tablespoon (or roughly 50 grams) per day.25 This may be due to clinical studies that have not exceeded a dose of 50 grams per day, and thus the potential adverse effects have not been adequately studied above this amount.

The PUFA content, as well as the low concentration of tocopherol and phenolic compounds, account for the low oxidative stability of chia oil. Within 300 days, a 30% drop in the tocopherol content of chia seed oil was observed.9 The antioxidant capacity of chia oil is relatively low due to the hydrophilic nature of the phenolic compounds within the chia seed. Despite chia seed’s rich omega-3 and omega-6 content, there is a technological disadvantage in the production of chia seed oil in regards to its stability and short shelf life, especially when exposed to light or oxygen. Chia seed oil is best kept in the refrigerator after opening and should be used quickly to gain its full range of nutrients.

Nutrient Profile26

Macronutrient Profile: (Per 1-ounce seeds)

138 calories
4.7 g protein
11.9 g carbohydrate
8.7 g fat

Secondary Metabolites: (Per 1-ounce seeds)

Excellent source of:

Manganese: 0.8 mg (40% DV)
Dietary Fiber: 9.8 g (39.2% DV)
Phosphorus: 244 mg (24.4% DV)
Magnesium: 95 mg (23.8% DV)

Very good source of:

Calcium: 179 mg (17.9% DV)
Thiamin: 0.2 mg (13.3% DV)
Niacin: 2.5 mg (12.5% DV)
Iron: 2.2 mg (12.2% DV)

Also provides:

Folate: 14 mcg (3.5% DV)
Potassium: 115 mg (3.3% DV)
Riboflavin: 0.05 mg (3% DV)

Trace amounts of:

Vitamin C: 0.5 mg (0.8% DV)
Vitamin E: 0.14 mg (0.7% DV)
Vitamin A: 15 IU (0.3% DV)

DV = Daily Value as established by the US Food and Drug Administration, based on a 2,000-calorie diet.

Strawberries-and-Cream-Chia-Pudding-4-2

Recipe: Strawberries and Cream Chia Pudding

Adapted from Emily Han27

Ingredients:

  • 8 ounces fresh strawberries
  • 3/4 cup coconut milk
  • 2 tablespoons honey
  • 1/2 teaspoon vanilla extract
  • 1/2 teaspoon grated lime zest
  • 1/4 cup chia seeds

Directions:

  1. Combine the strawberries, coconut milk, honey, vanilla, and lime zest in a blender. Puree until smooth. Taste and add more honey, if desired.

  2. Place the chia seeds in a large bowl and add the strawberry mixture. Whisk thoroughly to combine. Let the mixture stand for 10 minutes, then whisk again.

  3. Cover and refrigerate for at least four hours and up to three days. Stir before serving. The pudding will set up thicker the longer it sits.

References

  1. Salvia hispanica – L. Plants for a Future website. Available at: www.pfaf.org/user/Plant.aspx?LatinName=Salvia+hispanica. Accessed August 24, 2017.
  2. Muñoz LA, Cobos A, Diaz O, Aguilera JM. Chia seed (Salvia hispanica): An ancient grain and a new functional food. Food Reviews International. 2013;29:394-308.
  3. Taxon: Salvia hispanica L. US National Plant Germplasm System website. Available at: https://npgsweb.ars-grin.gov/gringlobal/taxonomydetail.aspx?32939. Accessed August 24, 2017.
  4. Kaiser C, Ernst M. Center for Crop Diversification Crop Profile: Chia. Lexington, KY: University of Kentucky College of Agriculture, Food and Environment. February 2016.
  5. Ali NM, Yeap SK, Ho WY, Beh BK, Tan SW, Tan SG. The promising future of chia, Salvia hispanica L. Journal of Biomedicine and Biotechnology. 2012;171956.
  6. Porras-Loaiza P, Jiménez-Munguía MT, Sosa-Morales ME, Palou E, López-Malo A. Physical properties, chemical characterization and fatty acid composition of Mexican chia (Salvia hispanica L.) seeds. International Journal of Food Science and Technology. 2014;49:571-577.
  7. Valdivia-López MA, Tecante A. Chia (Salvia hispanica): A review of native Mexican seed and its nutritional and functional properties. Advances in Food and Nutrition Research. 2015;75:54-71.
  8. Illian TG, Casey JC, Bishop PA. Omega 3 chia seed loading as a means of carbohydrate loading. Journal of Strength and Conditioning Research. 2011;25(1):61-65.
  9. Bodoira RM, Penci MC, Ribotta PD, Martínez ML. Chia (Salvia hispanica L.) oil stability: Study of the effect of natural antioxidants. LWT – Food Science and Technology. 2017;75:107-113.
  10. Kačmárová K, Lavová B, Socha P, Urminská D. Characterization of protein fractions and antioxidant activity of chia seeds (Salvia hispanica L.). Potravinarstvo. 2016;10(1):78-82.
  11. Pandey KB, Rizvi SI. Plant polyphenols as dietary antioxidants in human health and disease. Oxidative Medicine and Cellular Longevity. 2009;2(5):270-278.
  12. da Silva Marineli R, Moraes ÉA, Lenquiste SA, Godoy AT, Eberlin MN, Maróstica Jr MR. Chemical characterization and antioxidant potential of Chilean chia seeds and oil (Salvia hispanica L.). LWT – Food Science and Technology. 2014;59:1304-1310.
  13. Jeong SK, Park HJ, Park BD, Kim I. Effectiveness of topical chia seed oil on pruritus of end-stage renal disease (ESRD) patients and healthy volunteers. Ann Dermatol. 2010;22(2):143-148.
  14. Martínez-Cruz O, Paredes-López O. Phytochemical profile and nutraceutical potential of chia seeds(Salvia hispanica L.) by ultra high performance liquid chromatography. Journal of Chromatography A. 2014;1346:43-48.
  15. Cahill J. Ethnobotany of chia, Salvia hispanica L. (Lamiaceae). Economic Botany. 2003;57(4):604-618.
  16. Immel DL. Plant Guide: Chia. Washington DC: United States Department of Agriculture Natural Resources Conservation Service. 2003.
  17. Hershey DR. Don’t just pet your chia. Science Activities. 1995;32(2):8-12.
  18. Edwards O. Chia Pet. Smithsonian Magazine. December 2007. Available at: www.smithsonianmag.com/arts-culture/chia-pet-180308610/. Accessed August 24, 2017.
  19. Toscano LT, Oliveira da Silva CS, Toscano LT, Monteiro de Almeida AE, Santos AdC, Silva AS. Chia flour supplementation reduces blood pressure in hypertensive subjects. Plant Foods Hum Nutr. 2014;69:392-398.
  20. de Souza Ferreira C, de Sousa Fomes LdF, Santo da Silva GE, Rosa G. Effect of chia seed (Salvia hispanica L.) consumption on cardiovascular risk factors in humans: a systematic review. Nutrición Hospitalaria. 2015;32(5):1909-1918.
  21. Nieman DC, Cayea EJ, Austin MD, Henson DA, McAnulty SR, Jin F. Chia seed does not promote weight loss or alter disease risk factors in overweight adults. Nutrition Research. 2009;29:414-418.
  22. Nieman DC, Gillitt N, Jin F, et al. Chia seed supplementation and disease risk factors in overweight women: a metabolomics investigation. J Alt Complement Med. 2012;18(7):700-708.
  23. Ho H, Lee AS, Jovanonvski E, Jenkins AL, DeSouza R, Vuksan V. Effect of whole and ground Salba seeds (Salvia hispanica L.) on postprandial glycemia in healthy volunteers: A randomized controlled, dose-response trial. Eur J Clin Nutr. 2013;67:786-788.
  24. da Silva Marineli R, Lenquiste SA, Moraes ÉA, Maróstica Jr. MR. Antioxidant potential of dietary chia seed and oil (Salvia hispanica L.) in diet-induced obese rats. Food Research International. 2015;76:666-674.
  25. US Department of Health and Human Services and US Department of Agriculture. 2015-2020 Dietary Guidelines for Americans. 8th ed. December 2015. Available at: http://health.gov/dietaryguidelines/2015/guidelines. Accessed September 14, 2017.
  26. Basic Report: 12006, Seeds, chia seeds, dried. United States Department of Agriculture Agricultural Research Service website. Available at: https://ndb.nal.usda.gov/ndb/foods/show/3610. Accessed August 23, 2017.
  27. Han E. Dairy-Free Dessert Recipe: Strawberries & “Cream” Chia Pudding. The Kitchn website. May 8, 2013. Available at: www.thekitchn.com/recipe-strawberry-chia-pudding-recipes-from-the-kitchn-189016. Accessed August 23, 2017.
  28. Bauman H, Bates K. Food as Medicine: Strawberry (Fragaria x ananassa, Rosaceae). HerbalEGram. 2015;12(5). Available at: http://cms.herbalgram.org/heg/volume12/05May/FaM_Strawberry.html. Accessed September 11, 2017.
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Food as Medicine Horseradish (Armoracia rusticana, Brassicaceae)

History and Traditional Use

Range and Habitat

Horseradish (Armoracia rusticana, Brassicaceae) is a hardy perennial native to southeastern Europe and western Asia. Today, it is grown in the temperate regions of Europe, Asia, and North and South America, as well as some parts of Africa and New Zealand.1 The plant grows in clumps with bright green leaves that radiate out from the main taproot, which is cultivated as a food ingredient.2 Small, white, four-petaled flowers grow from a stalk that can reach two to three feet or higher when flowering.2 Young leaves two to three inches in length also can be harvested for use in salads.3

Horseradish is easy to cultivate and often will continue to thrive even during periods of neglect.4 While technically a perennial, it is best treated as an annual or biennial crop due to the root’s tendency to become woody and unpalatable with age. Once established, horseradish grows well in full sun and slightly moist soil.1


Phytochemicals and Constituents

Glucosinolates, sulfur-containing secondary metabolites, give horseradish its characteristic spicy flavor.5Horseradish contains eight different glucosinolates, of which sinigrin, gluconasturtiin, glucobrassicin, and neoglucobrassicin are the most common.5 Once inside the body, glucosinolates are broken down into powerful derivatives called isothiocyanates and indoles, which are believed to be the main cancer-preventive constituents of horseradish and other cruciferous vegetables (i.e., vegetables of the family Brassicaceae).1,6

Horseradish also contains minerals such as phosphorous, calcium, magnesium, and potassium.Freshly grated roots contain minimal fat, are low in calories, and rich in vitamin C. Cooking horseradish can strip it of its nutritional value, so it is best used fresh.1


Historical Uses

Horseradish root has been ground into a spice, prepared as a condiment, and used medicinally for more than 3,000 years. It was used topically by both the Greeks and Romans as a poultice to ease muscle pain, such as backaches and menstrual cramps.3 Internally, it was used to relieve coughs and as an aphrodisiac.4 Starting in the Middle Ages (ca. 1000-1300 CE), horseradish was incorporated into the Jewish Passover Seder as one of the maror, or bitter herbs.In the 16th century, Europeans began using horseradish in sauces and condiments as well as for its medicinal applications.

Historically, horseradish was used to treat a wide variety of illnesses including asthma, coughs, colic, toothache, and scurvy (due to its vitamin C content). Grated horseradish poultices were used to ease pain associated with gout and sciatica, and also were infused in milk to clarify the skin and remove freckles.3Currently, horseradish is consumed regularly in the form of ready-to-use sauces and dips.2 In 2005, the Horseradish Information Council reported that in the United States, 24 million pounds of horseradish roots were processed into six million gallons of prepared horseradish sauce.3


Modern Research & Uses

The chemoprotective role of horseradish’s gluconsinolate content against various types of cancers in humans has been widely studied.8,9 A hydrolyzed form of the glucosinolate sinigrin has been shown to suppress the growth of cancerous tumors in vitro and protect against further DNA damage.9,10 One hypothesis is that glucosinolates may work by enhancing the liver’s ability to detoxify carcinogens.10 Using a rat model, researchers found that sinigrin affects many organs involved in carbohydrate and lipid metabolism, including the liver, pancreas, and intestine.11 Sinigrin also reduced lipid levels in the blood, suggesting that it could be beneficial in reducing elevated triglyceride levels after meals, a risk factor for coronary artery disease.11

Horseradish also contains allyl isothiocyanate, which is a well-recognized antimicrobial agent against a variety of organisms including pathogens like Escherichia coli (E. coli), a common food-borne pathogen, and Helicobacter pylori (H. pylori), a bacteria known to cause stomach ulcers and increase the risk for gastric cancer.12 Due to its antibiotic properties, horseradish can be used to treat urinary tract infections and destroy bacteria in the throat that can cause bronchitis, coughs, and other related problems.13 In a recent study, isothiocyanates extracted from horseradish showed antimicrobial activity against ten different oral microorganisms.14 Although broccoli (Brassica oleracea var. italica), Brussels sprouts (B. oleracea var. gemmifera), and other cruciferous vegetables also contain these compounds, horseradish has up to ten times more glucosinolates than other members of the family Brassicaceae.10

Horseradish root was approved as a nonprescription medicine ingredient by the German Commission E for treatment of infections of the respiratory tract and as supportive treatment in urinary tract infections.13 In the United States, horseradish root is the active ingredient of Rasapen, a urinary antiseptic drug.13Horseradish is considered a strong diuretic and, coupled with its antibacterial properties, acts to flush out harmful bacteria or other inflammatory agents in the bladder sooner than they normally would be eliminated.10

Isothiocyanates in horseradish root are released when hydrolyzed by other active enzymes, which are activated only when the root is scratched.15 Fumes released from grating or cutting the root can irritate the membranes of the eyes and nose, and therefore horseradish should be prepared in a well-ventilated room and care should be taken in its use.


Nutrient Profile


Macronutrient Profile:
 (Per 1 tablespoon [15 g] raw horseradish)

Calories: 7

Protein: 0.18 g

Carbohydrates: 1.69 g

Fat: 0.1 g

Secondary Metabolites: (Per 1 tablespoon [15 g] raw horseradish)

Good source of:
Vitamin C: 3.7 mg (6.2% DV)

Vitamin K: 0.2 mcg (2.5% DV)

Folate: 9 mcg (2.25% DV)

Dietary fiber: 0.5 g (2% DV)

Potassium: 37 mg (1.1% DV)

Magnesium: 4 mg (1% DV)

Calcium: 8 mg (0.8% DV)

Zinc: 0.12 mg (0.8% DV)

Vitamin B6: 0.01 mg (0.5%DV)

Phosphorus: 5 mg (0.5% DV)

Niacin: 0.06 mg (0.3% DV)

DV = Daily Value, as established by the US Food and Drug Administration, based on a 2,000-calorie diet.

Recipe: Kale and Potato Hash

Recipe courtesy of EatingWell magazine16


Ingredients:

  • 8 cups torn kale leaves
  • 2 tablespoons freshly grated horseradish
  • 1 medium shallot, minced
  • 1/2 teaspoon freshly ground pepper
  • 1/4 teaspoon kosher salt
  • 2 cups shredded cooked potatoes
  • 3 tablespoons extra virgin olive oil

Directions:

  1. Place kale in a large microwave-safe bowl, cover, and microwave until wilted, about 3 minutes. Drain, cool slightly and finely chop.

  2. Meanwhile, mix horseradish, shallot, pepper, and salt in a large bowl. Add the chopped kale and potatoes; stir to combine.

  3. Heat oil in a large nonstick skillet over medium heat. Add the kale mixture, spread into an even layer, and cook, stirring every 3 to 4 minutes and returning the mixture to an even layer, until the potatoes begin to turn golden brown and crisp, 12 to 15 minutes total.

References

  1. Small E, ed. Culinary Herbs. Ottawa, ON: NRC Research Press; 1997.
  2. Van Wyk B-E. Food Plants of the World: An Illustrated Guide. Portland, OR: Timber Press; 2005.
  3. The Essential Guide to Horseradish. The Herbal Society of America website.  Available here. Accessed January 5, 2015.
  4. National Geographic Society. Edible: An Illustrated Guide to the World’s Food Plants. Washington, DC: National Geographic Society; 2008.
  5. Alnsour M, Kleinwächter M, Böhme J, Selmar D. Sulfate determines the glucosinolate concentration of horseradish in vitro plants (Armoracia rusticana Gaertn., Mey. & Scherb.). J Sci Food Agric. 2013;93(4):918-923.
  6. Rinzler CA. The New Complete Book of Herbs, Spices, and Condiments: A Nutritional, Medical, and Culinary Guide. New York, NY: Checkmark Books; 2001.
  7. US Department of Agriculture. USDA National Nutrient Database for Standard Reference, Release 27. Available here. Accessed January 5, 2015.
  8. Hayes JD, Kelleher MO, Eggleston IM. The cancer chemopreventive actions of phytochemicals derived from glucosinolates. Eur J Nutr. 2008;47(2):73-88.
  9. Bonnesen C, Eggleston IM, Hayes JD. Dietary indoles and isothiocyanates that are generated from cruciferous vegetables can both stimulate apoptosis and confer protection against DNA damage in human colon cell lines. Cancer Res. 2001;61(16):6120-6130. Available here. Accessed January 5, 2015.
  10. Patel DK, Patel K, Gadewar M, Tahilyani V. A concise report on pharmacological and bioanalytical aspect of sinigrin. Asian Pac J Trop Biomed. 2012;2(1):S446-S448.
  11. Okulicz M. Multidirectional time-dependent effect of sinigrin and allyl isothiocyanate on metabolic parameters in rats. Plant Foods Hum Nutr. 2010;65(3):217-224.
  12. Luciano FB, Holley RA. Enzymatic inhibition by allyl isothiocyanate and factors affecting its antimicrobial action against escherichia coli O157:H7. Int J Food Microbiol. 2009;131(2): 240-245.
  13. Blumenthal M, Goldberg A, Brinkmann J, eds. Herbal Medicine: Expanded Commission E Monographs.Austin, TX: American Botanical Council and Newton, MA: Integrative Medicine Communications; 2000.
  14. Park HW, Choi KD, Shin IS. Antimicrobial activity of isothiocyanates (ITCs) extracted from horseradish (Armoracia rusticana) root against oral microorganisms. Biocontrol Sci. 2013;18(3):163-168. Available here. Accessed January 5, 2015.
  15. Duke JA, ed. CRC Handbook of Medicinal Spices. Boca Raton, FL: CRC Press; 2002.
  16. Kale and Potato Hash. EatingWell. October/November 2005. Available here. Accessed January 13, 2005.

Food as Medicine: Kiwifruit (Actinidia deliciosa, Actinidiaceae)

Kiwifruit (Actinidia deliciosa, Actinidiaceae), also known by the less common name “Chinese gooseberry,” is one of 50 known species within the genus Actinidia.1 These species are climbing, woody vines with large, heart-shaped leaves and cream-colored flowers that bloom in the spring. The flowers are dioecious, with male and female blossoms found in separate individuals. The kiwifruit matures in early winter and typically has brown fuzzy skin. Depending on the species, the flesh is either green or yellow, but all species are filled with small black, edible seeds.1 While A. deliciosa accounts for about 90% of kiwifruit in international trade, two other species are cultivated and sold commercially: A. Chinensis and A. arguta.2 Actinidia deliciosa is the common green kiwifruit.3 The most common cultivar of A. chinensis is “Hort16A,” known by the brand name ZESPRI, or “gold kiwifruit.”4Actinidia arguta is referred to as “baby kiwi” or “grape kiwi” due to the small size of its fruits.2Actinidia species are native to southwestern China, but they are now cultivated in New Zealand, the United States, Italy, France, Chile, and Japan.5

Phytochemicals and Constituents

Kiwifruit provides fiber, potassium, folate, phosphorus, copper, and vitamins A, C, E, and K.3,6 In fact, one kiwifruit provides more than the Recommended Dietary Allowance (RDA) of vitamin C for adults and almost 35% of the RDA of vitamin K. Vitamin C has numerous health benefits, including anticarcinogenic and immune-regulating properties.3,7 In addition, it plays a role in the formation of collagen, a major component of connective tissue, skin, and bones. Vitamin C intake also has been shown to help mitigate a number of conditions, including cardiovascular disease and inflammation.8 Vitamin E is an antioxidant that stops the oxidation of low-density lipoprotein (LDL) cholesterol and protects cell membranes against damage caused by reactive oxygen species.9 Vitamin E also helps maintain the structure and function of skeletal, cardiac, and smooth muscles. Vitamin K regulates blood clotting, aids in the transfer of calcium through the body, and supports bone health, reducing the risk of osteoporosis and bone fractures due to age.10

Kiwifruit is also a good source of fiber, which contributes to its laxative effect. Additionally, the lignins in cellulose (a form of dietary fiber) are believed to have antimutagenic properties due to their ability to increase the adsorption of aromatic amines in the gut, thus preventing them from entering the bloodstream. Aromatic amines can act as carcinogens after they have been metabolized by the liver.3

One of the interesting compounds present in kiwifruit is actinidin, an enzyme that helps to hydrolyze proteins. Due to the actinidin content of kiwifruit, other fruits and dairy products will soften or curdle upon prolonged contact with the chopped fruit, so kiwifruit should be added at the last minute to fruit salads and other mixed preparations. Actinidin has been shown to improve digestion by assisting with protein digestion and digestive motility.11 Kiwifruit contains numerous other bioactive compounds, including organic acids, plant pigments, and polyphenols. The primary organic acid in kiwi is citric acid, but it also contains malic, quinic, gallic, and oxalic acids. Organic acids provide the fruits with significant antioxidant properties.

Some of the plant pigments present in kiwifruit include carotenoids and chlorophyll, and some cultivars also contain anthocyanins.11 The carotenoids include beta-carotene, lutein, violaxanthin, and 9’-cis-neoxanthin.3 When compared with other commonly consumed fruits, kiwifruit is the richest source of lutein, which is a carotenoid that is highly concentrated in the macula of the eye and is associated with lowering risk of cataracts. All Actinidia species contain chlorophylls a and b, but levels are much lower in the gold kiwi variety. Some kiwifruits also contain anthocyanins, but they are not a significant component of the antioxidant capacity of the fruit. Glutathione is another important antioxidant present in kiwifruit, and it not only prevents oxidative damage of cells but also helps to keep vitamins C and E in their active form, regenerating their antioxidant capacities.11

Historical and Commercial Uses

Kiwifruit is featured in Chinese literature dating back to the 15th century.12 The kiwifruit was originally called mi hou tao, or “monkey peach,” because monkeys would eat the fruit in the wild.4 Traditionally, both the root and the fruit of A. chinensis were used in traditional Chinese medicine and are known as xiao yang tao. The root of A. Chinensis contains antiangiogenic phytochemicals including triterpenes, polyphenols, and anthraquinones, and it has been noted in the Chinese pharmacopeia as being useful for treating many diseases, such as stomach, rectal, and breast cancers, as well as hepatitis viral infections.12-14 The fruit of A. Chinensis was used as a juice to quench thirst, aid digestion, clear heat, and reduce irritability, inflammation, and vomiting.3,14

Other Actinidia species were used for their therapeutic effects as well. Historically, A. macrosperma was used to stimulate the immune system and A. polygama was used as an anti-inflammatory agent and to counteract allergies due to its anti-asthmatic effect.3,15

Modern Research

Clinical trials for kiwifruit primarily have focused on its effects on the digestive, immune, and cardiovascular systems. Preliminary research has also investigated the antioxidant properties of kiwifruit and its possible inhibitory effect on cancerous cell growth.

Gastrointestinal System

Clinically, kiwifruit has been shown to have a laxative effect. Daily consumption of the fruit improved the frequency and ease of bowel movements and improved stool bulk and softness in healthy older adults.3 In another study, researchers found that daily kiwifruit intake relieved symptoms in subjects suffering from chronic constipation, with no reports of adverse effects like diarrhea.3 Additionally, a trial in healthy subjects who were not experiencing constipation found no adverse gastrointestinal effects from daily consumption of kiwifruit.16

These gastrointestinal benefits are attributed to the lubricating effects of kiwifruit’s pectin and the enzyme actinidin, which combine with the enzymes in the stomach and the small intestine to improve digestion.4The pectin and fiber present in kiwifruits also function as prebiotics. Prebiotics help to modify the composition of the bacterial flora in the gut so that healthy bacteria are stimulated and harmful bacteria are suppressed. An in vitro study looked at the prebiotic effect of the pectin present in kiwifruit compared to other prebiotics like inulin, guar gum, and citrus pectin. The pectin in kiwifruit was more effective than these prebiotics in reducing the intestinal adhesion of harmful bacteria and increasing the adhesion of beneficial bacteria.17 In a mouse study on irritable bowel disease (IBD), extracts of both green and golden kiwifruit were administered, resulting in a potent anti-inflammatory effect. These results indicate that further research should be done exploring the medicinal properties of kiwifruits in the treatment of IBD.18

Antibacterial and Immunological Activity

In an in vitro study, essential oil from A. macrosperma produced inhibitory effects against a number of common bacteria, including Escherichia coli and Staphylococcus aureus, as well as three common fungal species.3 In a mouse study, kiwifruit extract was shown to alter innate and acquired immunity when the mice were injected with cholera and diphtheria/tetanus vaccines.15 This could have implications for improving immunity in vaccinated individuals, particularly children and other high-risk populations.

Other animal studies have shown that extracts of A. arguta may have anti-allergenic effects, implying a potential for the use of kiwi extracts as therapies for allergy conditions like bronchial asthma or eczema.3 A human trial observed the effects of daily intake of golden kiwifruit on both older adults (older than 65 years) and young children (ages 2-5) in relation to cold and flu-like illnesses. For the adults, those who ate four kiwifruits daily had symptoms for fewer days over the course of a cold than the adults who ate two bananas (Musa acuminata, Musaceae) daily. In the preschool children, the odds of getting a cold or the flu decreased by almost half in the children who ate two kiwifruits daily instead of one banana.4

Cardiovascular System

There is some evidence that kiwifruit may have the ability to affect risk factors for cardiovascular disease, like blood pressure, plasma triglycerides, and platelet aggregation. A human study showed that eating two to three kiwifruits per day reduced triglyceride levels by 15% and reduced platelet aggregation response by18% compared to control.19Multiple studies have shown that daily kiwi consumption improves not only triglyceride levels but also the ratio of total cholesterol to high-density lipoprotein (HDL) cholesterol. One clinical trial studied male smokers who ate three kiwis per day for eight weeks. The patients had significantly reduced blood pressure and angiotensin-converting enzyme (ACE) activity (a component of the blood pressure-regulation process), especially those with hypertension. A number of in vitro studies support the claim that kiwifruit reduces platelet aggregation, but clinical trials are conflicting and more human studies are needed to confirm this effect.4

Antioxidant and Cytotoxic Properties

The vitamin and phytochemical composition of kiwifruit give it powerful antioxidant properties. An in vivo study showed that kiwifruit juice ingestion increased plasma antioxidant capacity within 30 minutes and that these levels were sustained for up to 90 minutes. Though this was not a long-term study, this may have implications for kiwifruit’s ability to fight oxidative stress.3 Similar findings were established through two human studies in the United Kingdom, which showed that kiwifruit consumption improved antioxidant status of both the plasma and lymphocytes of participants. One of these studies also showed that kiwifruit seemed to stimulate DNA repair. A pilot study was performed to extrapolate on this possibility and the results showed that kiwi aided DNA repair for an average of 13 hours after ingestion.7

Though vitamin C is known for its antioxidant power, it also has a synergistic effect on iron absorption. In a study of young women with mild anemia (iron deficiency), participants who consumed two golden kiwifruits with an iron-fortified cereal daily had significantly improved iron levels compared to participants who ate the cereal with a banana. The vitamin C content, along with the carotenoids lutein and zeaxanthin present in kiwifruits, are likely responsible for this outcome.4

There is a great deal of investigation into the role of antioxidants and other phytochemicals in the prevention of cancerous cell growth, but despite kiwifruit’s history of use in traditional Chinese medicine, there are few clinical trials establishing the connection of the fruit and its constituents with cancer prevention or treatment. In vitro studies have shown that extracts of Actinidia species may be toxic to cancer cells. Additionally, mice studies have shown that kiwifruit juice inhibits the growth of sarcoma cells.12 Another mouse study showed that catechin in the stems of A. arguta and the juice of A. deliciosa increased bone marrow proliferation, which may have implications for reducing the adverse effects of chemotherapy treatments. There has also been evidence suggesting that the prebiotic effect of fiber found in foods may change the bacteria in the colon, providing protection against colon cancer.3

Consumer Considerations

Though it is poorly understood, there is an allergy risk associated with the fruits of Actinidia species. Allergic reactions can range from mild itching of the throat, mouth, and lips, and swelling to anaphylaxis, though it is more common for reactions to be mild. The more severe reactions typically occur in children.4The prevalence of allergies to Actinidia fruits may vary geographically; in France, Finland, and Sweden, kiwifruit is one of the top ten most common allergens.16 Allergies to kiwifruit are often cross-reactive with other common allergens such as pollens, rye (Secale cereale, Poaceae), hazelnut (Corylus avellana, Betulaceae), chestnut (Castanea spp., Fagaceae), banana, and avocado (Persea Americana, Lauraceae). Heat treatment and industrial homogenization have been shown to greatly reduce the allergic reactivity of green kiwi. These treatments are often performed on processed products like beverages and jams.20

Kiwifruit contains oxalate, which is from the salt of oxalic acid. Oxalates can cause oral irritation in some individuals, and they can be risky for individuals with a history of calcium oxalate-containing kidney stones. Oxalate in high concentrations can also reduce the bioavailability of calcium, magnesium, and iron in the body.3 Though kiwifruit contains more than 10 mg of oxalate per serving (enough to be considered high levels), it would require daily consumption of large quantities of kiwifruit for the levels of oxalates in the body to become dangerous. Additionally, oxalate content decreases during storage.16

Nutrient Profile21

Macronutrient Profile: (Per one fruit [approx. 69 grams])

42 calories
0.8 g protein
10.1 g carbohydrate
0.4 g fat

Secondary Metabolites: (Per one fruit [approx. 69 grams])

Excellent source of:

Vitamin C: 64 mg (106.7% DV)
Vitamin K: 27.8 mcg (34.8% DV)

Good source of:

Dietary Fiber: 2.1 g (8.4% DV)
Potassium: 215 mg (6.1% DV)
Vitamin E: 1 mg (5% DV)

Also, provides:

Folate: 17 mcg (4.3% DV)
Manganese: 0.07 mg (3.5% DV)
Magnesium: 12 mg (3% DV)
Calcium: 23 mg (2.3% DV)
Phosphorus: 23 mg (2.3% DV)
Vitamin B6: 0.04 mg (2% DV)
Thiamin: 0.02 mg (1.3% DV)
Niacin: 0.24 mg (1.2% DV)
Riboflavin: 0.02 mg (1.2% DV)
Vitamin A: 60 IU (1.2% DV)
Iron: 0.2 mg (1.1% DV)

DV = Daily Value as established by the US Food and Drug Administration, based on a 2,000-calorie diet.

Recipe: Kiwi, Lemon, and Rosemary Shrub

Courtesy of Jerry James Stone22

Ingredients:

  • 1 1/2 pounds kiwifruit
  • 2 slices of lemon
  • 1 sprig of rosemary
  • 1 cup sugar
  • 1 cup champagne vinegar

Directions:

  1. Peel and thinly slice the kiwifruit. Arrange a layer of kiwifruit in a quart-sized jar and sprinkle with sugar. Repeat the layering until all the sugar and fruit is in the jar. Seal and let stand for five hours.

  2. Add the lemon, rosemary, and vinegar to the jar. Seal and shake to combine and dissolve the sugar, then let stand for 24 hours.

  3. Strain the mixture through a sieve into a clean quart-sized jar. Seal and refrigerate. To serve, mix two tablespoons of the shrub with sparkling water in an ice-filled glass.

References

  1. The National Geographic Society. Edible: An Illustrated Guide to the World’s Food Plants. Washington, DC: The National Geographic Society; 2008.
  2. Wojdyło A, Nowicka P, Oszmiański J, Golis T. Phytochemical compounds and biological effects of Actinidia fruits. J Funct Foods. 2017;30:194-202. doi:10.1016/j.jff.2017.01.018.
  3. Hunter DC, Skinner MA, Ferguson AR, Stevenson LM. Kiwifruit and health. In: Bioactive Foods in Promoting Health: Fruits and Vegetables. Auckland, New Zealand; 2010:565-580. doi:10.1016/B978-0-12-374628-3.00037-2.
  4. Stonehouse W, Gammon CS, Beck KL, Conlon C, von Hurst PR, Kruger R. Kiwifruit: our daily prescription for health. Can J Physiol Pharmacol. 2013;91(6):442-447. doi:10.1139/cjpp-2012-0303.
  5. van Wyk B-E. Food Plants of the World: An Illustrated Guide. Portland, OR: Timber Press; 2005.
  6. Murray M, Pizzorno J, Pizzorno L. The Encyclopedia of Healing Foods. New York, NY: Atria Books; 2005.
  7. Rush E, Ferguson LR, Cumin M, Thakur V, Karunasinghe N, Plank L. Kiwifruit consumption reduces DNA fragility: a randomized controlled pilot study in volunteers. Nutr Res. 2006;26(5):197-201. doi:10.1016/j.nutres.2006.05.002.
  8. Carr AC, Pullar JM, Moran S, Vissers MCM. Bioavailability of vitamin C from kiwifruit in non-smoking males: determination of “healthy” and “optimal” intakes. J Nutr Sci. 2012;1:e14. doi:10.1017/jns.2012.15.
  9. Weil A, Becker B. Facts about vitamin E. Weil website. August 2016. Available at: www.drweil.com/vitamins-supplements-herbs/vitamins/facts-about-vitamin-e/. Accessed June 21, 2017.
  10. Ehrlich SD. Vitamin K. University of Maryland Medical Center website. July 16, 2013. Available at: www.umm.edu/health/medical/altmed/supplement/vitamin-k. Accessed June 22, 2017.
  11. Drummond L. Chapter three — The composition and nutritional value of kiwifruit. Adv Food Nutr Res. 2013;68:33-57. doi:http://dx.doi.org/10.1016/B978-0-12-394294-4.00003-1.
  12. Motohashi N, Shirataki Y, Kawase M, et al. Cancer prevention and therapy with kiwifruit in Chinese folklore medicine: A study of kiwifruit extracts. J Ethnopharmacol. 2002;81(3):357-364. doi:10.1016/S0378-8741(02)00125-3.
  13. Zhu WJ, Yu DH, Zhao M, et al. Antiangiogenic triterpenes isolated from Chinese herbal medicine Actinidia chinensis Planch. Anti-Cancer Agents Med Hist. 2013;13(2):195-198. doi:10.2174/187152013804711146.
  14. Hsu HY. Oriental Materia Medica: A Concise Guide. Long Beach, CA: Oriental Healing Arts Institute; 1986.
  15. Shu Q, Mendis De Silva U, Chen S, et al. Kiwifruit extract enhances markers of innate and acquired immunity in a murine model. Food Agric Immunol. 2008;19(2):149-161. doi:10.1080/09540100802117198.
  16. Singletary K. Kiwifruit. Nutr Today. 2012;47(3):133-147. doi:10.1097/NT.0b013e31825744bc.
  17. Parkar SG, Redgate EL, Wibisono R, Luo X, Koh ETH, Schröder R. Gut health benefits of kiwifruit pectins: Comparison with commercial functional polysaccharides. J Funct Foods. 2010;2(3):210-218. doi:10.1016/j.jff.2010.04.009.
  18. Edmunds SJ, Roy NC, Love DR, Laing WA. Kiwifruit extracts inhibit cytokine production by lipopolysaccharide-activated macrophages, and intestinal epithelial cells isolated from IL10 gene deficient mice. Cell Immunol. 2011;270(1):70-79. doi:10.1016/j.cellimm.2011.04.004.
  19. Park YS, Leontowicz H, Leontowicz M, et al. Comparison of the contents of bioactive compounds and the level of antioxidant activity in different kiwifruit cultivars. J Food Compos Anal. 2011;24(7):963-970. doi:10.1016/j.jfca.2010.08.010.
  20. Nishiyama I. Fruits of the Actinidia genus. Adv Food Nutr Res. 2007;52(6):293-324. doi:10.1016/S1043-4526(06)52006-6.
  21. Basic Report: 09148, Kiwifruit, green, raw. United States Department of Agriculture Agricultural Research Service website. May 2016. Available at: https://ndb.nal.usda.gov/ndb/foods/show/2253. Accessed June 22, 2017.
  22. Stone JJ. Kiwi, lemon & rosemary shrub (drinking vinegar). Jerry James Stone website. December 4, 2013. Available at: jerryjamesstone.com/recipe/kiwi-lemon-rosemary-shrub-drinking-vinegar/. Accessed June 22, 2017. [Editor’s note: The linked webpage contains profanity.]

Food as Medicine: Mango (Mangifera indica, Anacardiaceae)

History and Traditional Use

Range and Habitat

Mangifera indica (Anacardiaceae) is a tropical tree that grows from 33 feet to 131 feet in height and produces large, oval-shaped fruits that are red and gold when ripe, though some cultivars are green or yellow.1 The smooth-edged leaves of the mango tree are reddish when young, becoming dark green and shiny as they mature. The tree produces small pinkish-white flowers that precede the fruit.2,3 The mango fruit is a drupe, or stone fruit, containing a large single seed surrounded by fleshy pulp and a thin, leathery skin.4 The mango tree begins to bear fruit four to six years after planting and continues to produce fruit for about 40 years.3,4 Trees older than 10 years tend toward alternate or biennial bearing, producing fruit every other year.5

While the most commonly used part of the plant is the fruit, the mango tree has a variety of traditional uses that make use of the roots, peel, stem bark, leaves, flowers, and seed kernels. These parts typically contain greater amounts of bioactive compounds, including mangiferin, then the fruit.4 Belonging to the same plant family as the cashew (Anacardium occidentale) and pistachio (Pistacia vera), the mango is native to India and Burma, and has been cultivated since 2000 BCE.2 The mango was introduced to Africa about 1,000 years ago and to tropical America in the 19th century.1,2 Wild fruits have a minimal resemblance to the cultivated mangos, having a much smaller size and unpleasant turpentine-like taste. Currently, mangos are grown in tropical and warm temperate climates.3 India remains the largest producer, growing 65% of the world’s mango crop.5

Phytochemicals and Constituents

The macro- and micro nutrient composition and bioactive compounds present in M. indica contribute to its many health benefits. Mango fruits are a rich source of vitamins A, B and C. Mangos are also a good source of both soluble and insoluble fiber.3 Soluble fiber can help prevent cardiovascular disease and improve gastrointestinal health.

Mango is a source of many pharmacologically and medically important chemicals, including mangiferin, mangiferin acid, hydroxy-mangiferin, flavonoids, phenolic acids, and carotenes.6 Different parts of the plant have different chemical compositions. The bark, for example, contains catechins, amino acids, and phenolic and triterpenoid compounds.7,8 Due to these constituents, mango bark extract has shown antioxidant, immune system-enhancing, anti-inflammatory, antibacterial, antiviral, and antifungal activities, which correspond to many of mango’s traditional medicinal uses.7 The xanthone mangiferin is found in many different plants across the Anacardiaceae family and shows promising results in the areas of antitumor, anti-diabetic, and anti-microbial actions.

The health benefits of the fruit pulp are due to its high concentration of antioxidant nutrients and phytochemicals, such as carotenoids. Carotenoids play an important role in protective health mechanisms against some forms of cancer, cardiovascular disease, and macular degeneration, as well as improving immune health.9 Specifically, mangos are high in beta-carotene, a precursor of vitamin A. Mango also contains smaller amounts of lutein and zeaxanthin, two carotenoids important for maintaining eye health and preventing macular degeneration. These phytochemicals are antioxidants, meaning that they slow or prevent the oxidative process, thereby preventing or repairing damage to cells in the body.10

The polyphenols that have been identified in the mango fruit include gallic acid, Gallo-tannins, quercetin, isoquercitrin, mangiferin, ellagic acid, and beta-glucogallin. These polyphenols have powerful antioxidant activity as well as other potential therapeutic effects. Gallic acid, for example, is known to have anti-inflammatory and antitumor activities, while ellagic acid has been found to exhibit antimutagenic, antiviral, and antitumor effects.4

The most biologically active compound that has been studied in the mango tree is mangiferin. Mangiferin is synthesized by the plant as a chemical defense compound.6,11 Plant parts that contain the highest amounts of mangiferin include the leaves, stem bark, heartwood, and roots. Currently, researchers are investigating potential methods of processing mango bark and peel into a palatable ingredient or food additive. Mangiferin (not to be confused with the previously mentioned mangiferin) is one of a number of enzymes present in mangos that improves digestion. Others include catechol oxidase and lactase.3

Historical and Commercial Uses

Mangifera indica has been used in Ayurveda, India’s primary system of traditional medicine, for more than 4,000 years. The mango was thought to have aphrodisiacal properties and is still viewed as sacred today.3A variety of the plant’s parts are used as a paste or powder for cleaning the teeth, and the juice of the mango is considered a restorative tonic, as well as a treatment for heat stroke.6 Numerous parts of the mango tree are used in Ayurvedic medicine as an antiseptic, an astringent to tone lax tissues, a laxative, a diuretic, and to increase sweating, promote digestion, and expel parasitic worms or other internal parasites.12 The seeds have been used as an astringent and as a treatment for asthma. Fumes from the burning leaves are used as an inhalant to relieve hiccups and sore throats.6 The bark is used as an astringent in diphtheria and rheumatism (disorders of the joints and connective tissues), and the gum was used in dressings for cracked feet and for scabies (an infestation of the skin by the human itch mite [Sarcoptes scabiei var. hominis]).

Current Ayurvedic practices use various parts of the mango for different ailments. For diarrhea, mango leaves are pounded together and taken with rice water.13 For nosebleeds, the juice of the mango seed is placed into the nostrils. For an enlarged spleen, ripe mango juice is consumed with honey. To treat gonorrhea, mango bark is pounded and added to milk and sugar. In some tropical countries, mango is actually used as a meat tenderizer, due to the power of the proteolytic enzymes that break down proteins.3In traditional ethnoveterinary medicine, all parts of the mango are used to treat abscesses, broken horns, rabid dog bites, tumors, snake bites, stings, heat stroke, miscarriage, bacterial illness, blisters and wounds in the mouth, inflammation of the inner ear, colic, diarrhea, liver disorders, excessive urination, tetanus, and asthma.14

Among the Tikunas, an indigenous people of Brazil, Colombia, and Peru, a mango leaf decoction was used as a contraceptive and abortifacient. Reportedly, taking a cupful on two successive days during menstruation acted as a contraceptive, and taking it for three days caused abortion.11,15

Mango fruit is processed at two stages of maturity. Green fruit is used to make chutney, pickles, curries, and dehydrated products like dried mango, amchoor (raw mango powder), and Panna (green mango beverage). Ripe fruit is processed into canned and frozen slices, pulp, concentrate, juices, nectar, jam, purée, cereal flakes, toffee, and various dried products.4

Modern Research

Studies indicate that M. indica possesses myriad therapeutic properties, including antidiabetic, antioxidant, antiviral, cardiotonic, hypotensive, and anti-inflammatory.6 Each of the mango’s parts — fruit, pulp, peel, seed, leaves, flowers, and bark — can be used therapeutically.

A 2000 study found that mango stem bark extract showed a powerful scavenging activity of hydroxyl radicals and acted as a chelator of iron.6 Although iron is an essential mineral, it is toxic in excessive amounts. Iron chelators could be an important approach to lessen iron-induced oxidative damage and prevent iron accumulation in diseases in which accumulation is prevalent, such as hemochromatosis, a metabolic disorder in which the body absorbs too much iron, and thalassemia, a rare, inherited blood disorder caused by a lack of hemoglobin, which results in fewer healthy red blood cells.4 This same study found a significant inhibitory effect on the degradation of brain cell membranes in an animal model and prevented DNA damage caused by some chemotherapy treatments.6,16

Polyphenolic compounds and related bioactivity are higher in the mango peel than the fruit, and higher still in the leaves and stem bark.4 The bark is one of the main parts of the tree used for medicinal purposes. A standardized aqueous extract of M. indica stem bark called Vimang (LABIOFAM Entrepreneurial Group; La Habana, Cuba) has been developed in Cuba. This extract has shown antioxidant, anti-inflammatory, and immunomodulatory properties and has been used in many countries for the treatment of heavy menstrual bleeding, diarrhea, syphilis, diabetes, scabies, cutaneous infections, and anemia.4,7

Much of the current research looks at extracts of mango bark or seed. There is a limited amount of literature that looks into the consumption of the mango fruit itself. However, a 2011 study looked at the consumption of freeze-dried mango fruit and its effects on weight loss and glucose tolerance, compared to hypolipidemic and hypoglycemic drugs, in mice fed a high-fat diet.17 In the study, consumption of freeze-dried mango prevented the increase in fat mass and the percentage of body fat. Compared with controls, mice given the freeze-dried mango had improved glucose tolerance and lowered insulin resistance.

Functional and medicinal properties of the non-fruit portions of the mango provide promising data for future uses of the plant and may allow for less waste of the non-edible parts of the mango. The mango peel, for example, constitutes about 15-20% of the mango fruit and typically is discarded prior to consuming the fruit. In commercial processing, the discarded peels become a wasteful by-product.18 A 2015 study conducted chemical analysis and determination of the bioactive compounds in a flour made from green mango peel.19 The mango peel flour had 54 g of total dietary fiber per 100 g of dry sample, compared to 1.8 g of total dietary fiber in wheat flour. The mango peel flour also contained 21.7 mg/g of total phenolic contents and 22.4 mg/g of total flavonoid contents.

The results of this study suggest that the mango peel flour exhibited functional properties similar to wheat flour, and could serve as an acceptable substitute in baked goods and other flour-containing foods. Dietary fiber in mango peel has been shown as a favorable source of high-quality polysaccharides due to its high starch, cellulose, hemicellulose, lignin, and pectin content combined with its low-fat content.18 In Vitro starch studies suggest low glycemic responses from mango peel fiber, which suggests a potential use for diabetic individuals.

Mango kernel oil has recently attracted attention due to its unsaturated fatty acid composition.18 Mango kernel oil has been widely researched for its function as an antioxidant and antimicrobial agent due to its high polyphenolic content.4 The major phenolic compounds in mango seed kernels are (in order of decreasing concentration): tannins, vanillin, coumarin, cinnamic acid, ferulic acid, caffeic acid, gallic acid, and mangiferin, all providing antioxidant protection.

Health Considerations

Possibly explained by its distant relation to poison sumac (Toxicodendron vernix, Anacardiaceae) and poison ivy (T. radicans), mango peel may be irritating to the skin,3 particularly to people who are highly sensitive to these plants. This is due to the presence of alk(en)ylresorcinols, a mixture of substances that can cause contact dermatitis to those who are allergic or sensitive to it.20 Alk(en)ylresorcinol is similar to urushiol, the toxic resin that causes an itchy rash in those who come into contact with poison ivy. These allergens are more prevalent in the peel than the flesh. In one study, four patients developed hives and eczematous rash after exposure to mangos or mango trees. Children and other persons with food allergies should take caution when handling and consuming mango. Although allergy to mango is infrequent, mango has been identified as an allergy-provoking food in some individuals with other food allergies.


Nutrient Profile21

Macronutrient Profile: (Per 1 cup mango fruit)

99 calories
1.35 g protein
24.7 g carbohydrate
0.63 g fat

Secondary Metabolites: (Per 1 cup mango fruit)

Excellent source of:
Vitamin C: 60.1 mg (100.2% DV)
Vitamin A: 1,785 IU (35.7% DV)

Very good source of:
Folate: 71 mcg (17.75% DV)
Dietary Fiber: 2.6 g (10.4% DV)
Vitamin B6: 0.2 mg (10% DV)

Good source of:
Vitamin K: 6.9 mcg (8.63% DV)
Potassium: 277 mg (7.9% DV)
Vitamin E: 1.48 mg (7.33% DV)
Niacin: 1.1 mg (5.5% DV)

Also, provides:
Magnesium: 16 mg (4% DV)
Riboflavin: 0.06 mg (3.53% DV)
Thiamin: 0.05 mg (3.33% DV)
Phosphorus: 23 mg (2.3% DV)
Calcium: 18 mg (1.8% DV)
Iron: 0.26 mg (1.44% DV)

DV = Daily Value as established by the US Food and Drug Administration, based on a 2,000 calorie diet.

Recipe: Mango and Watermelon Salad

Adapted from Mango.org22

Ingredients:

  • 2 large, ripe mangos, peeled, pitted, and diced
  • 1 cup watermelon, diced
  • 1/4 cup red onion, finely diced
  • 1 jalapeño pepper, stemmed, seeded, and finely diced
  • 12 cherry tomatoes, cut in half
  • 1 cup fresh arugula, washed and dried
  • 1 clove garlic, minced
  • 2 tablespoons fresh lemon juice
  • 1 tablespoon extra-virgin olive oil
  • 2 teaspoons honey
  • 1/2 teaspoon kosher salt
  • 3 tablespoons cilantro, chopped

Directions:

  1. Combine mango, watermelon, onion, pepper, tomato, and arugula in a large bowl. Toss to combine.

  2. Whisk together remaining ingredients and taste, adjusting seasoning if necessary. Drizzle dressing over the salad, toss to

    combine,

    and serve.

References

  1. Van Wyk B-E. Food Plants of the World. Portland, OR: Timber Press; 2006.
  2. The National Geographic Society. Edible: An Illustrated Guide to the World’s Food Plants. Washington, DC: National Geographic Society; 2008.
  3. Murray M, Pizzorno J, Pizzorno L. The Encyclopedia of Healing Foods. New York, NY: Atria Books; 2005.
  4. Masibo M, He Q. Mango bioactive compounds and related nutraceutical properties: A review. Food Rev Int. 2009;25:346-370.
  5. Morton JF. Mango. In: Morton JF. Fruits of Warm Climates. Miami, FL: J.F. Morton; 1987:221-239.
  6. Shah KA, Patel MB, Patel RJ, Parmar PK. Mangifera indica (Mango). Pharmacogn Rev. 2010;4(7):42-48.
  7. Wauthoz N, Balde A, Balde ES, Damme MV, Duez P. Ethnopharmacology of Mangifera indica L. bark and pharmacological studies of its main c-glucosylxanthone, mangiferin. Int J Biomed Pharma Sci. 2007;1(2):112-119.
  8. Hamid K, Algahtani A, Kim MS, et al. Tetracyclic triterpenoids in herbal medicines and their activities in diabetes and its complications. Curr Top Med Chem. 2015;15(23):2406-2430.
  9. Hewavitharana AK, Tan ZW, Shimada R, Shaw PN, Flanagan BM. Between fruit variability of the bioactive compounds, B-carotene and mangiferin, in mango. Nutrition and Dietetics. 2013;70:158-163.
  10. Johnson EJ. The role of carotenoids in human health. Nutr Clin Care. 2002;5(2):56-65.
  11. Schultes RE, Raffauf RF. The Healing Forest: Medicinal and Toxic Plants of the Northwest Amazonia.Portland, OR: Dioscorides Press; 1990.
  12. Johnson EJ. The role of carotenoids in human health. Nutr Clin Care. 2002;5(2):56-65.
  13. Amra (Mangifera indica) National R&D Facility for Rasayana website. Available here. Accessed May 19, 2016.
  14. Williamson EM. Major Herbs of Ayurveda. London, UK: Elsevier Science Limited; 2002.
  15. Duke JA, Vasquez R. Amazonian Ethnobotanical Dictionary. Boca Raton, FL: CRC Press; 1994.
  16. Martinez G, Delgado R, Perez G, Garrido G, Nunez Selles AJ, Leon OS. Evaluation of the in-vitroantioxidant activity of Mangifera indica L: extract (Vimang). Phytother Res. 2000;14:424–7.
  17. Lucas EA, Li W, Peterson SK, et.al. Mango modulates body fat and plasma glucose and lipids in mice fed a high-fat diet. Brit J Nutr. 2011;106:1495-1505.
  18. Tiwari BK, Brunton NP, Brennan CS. Handbook of Plant Food Phytochemicals: Sources, Stability and Extraction. West Sussex, UK: John Wiley & Sons, Ltd; 2013.
  19. Abidin NSA, Mohamad SN, Jaafar MN. Chemical composition, antioxidant activity and functional properties of mango (Mangifera indica L. var Perlis Sunshine) peel flour. Appl Mech Mater. 2015(754-755):1065-1070.
  20. Knödler M, Reisenhauer K, Schieber A, Carle R. Quantitative determination of allergenic 5-Alk(en)ylresorcinols in mango (Mangifera indica L.) peel, pulp, and fruit products by high-performance liquid chromatography. J Agric Food Chem. 2009;57:3639-3644.
  21. Basic Report, 09176, Mangos, raw. Agricultural Research Service, USDA website. Available here. Accessed May 19, 2016.
  22. National Mango Board. Mango and watermelon salad. Mango.org website. Available here. Accessed May 18, 2016.

Food as Medicine: Strawberry (Fragaria x ananassa, Rosaceae)

History and Traditional Use

Range and Habitat

Strawberry plants are considered herbaceous perennials and have a low-growing habit, reproducing horizontally via rooting runners or stolons.1 Each plant has a compressed, modified stem from which fibrous roots grow downward and multiple stems grow upward from a rosette. Strawberry plants produce a three-part leaflet with coarsely serrated edges. Flowers are white with many stamens and often appear in clusters on short, sturdy stems arising from the crown of the plant. Each flower produces a strawberry, which, botanically speaking, is the ripened receptacle, or base, of the flower.1

Strawberries are indigenous to both Europe and the Americas.2 The modern garden strawberry (Fragaria x ananassa) was developed in the 18th century from two North American species, the Virginia or scarlet strawberry (F. viriginiana), and the Chilean or beach strawberry (F. chiloensis).1 These two strains were crossed to produce larger fruit with a sweeter flavor and distinct fragrance. Today, Australia, Italy, the United States, France, Canada, New Zealand, and Japan commercially produce the largest amount of strawberries.3 The world’s leading producer of strawberries is the United States, with nearly 1.3 million metric tons produced primarily from California followed by Florida and Oregon.

Strawberries are susceptible to a wide variety of plant diseases and pests. For this reason, conventionally grown strawberry plants and fruits are often laden with pesticide and insecticide residues. The Environmental Working Group (EWG) considers the strawberry one of its “Dirty Dozen,” a list of 12 commonly consumed, conventionally grown produce items that are consistently high in harmful pesticide residues.4

Phytochemicals and Constituents

Strawberries, like most dark-colored berries, contain a complex series of phytochemicals that can be divided into six main groups: anthocyanins, flavonols, flavanols, ellagitannins, ellagic acid glycosides, and cinnamic acid conjugates.5 These compounds have significant health benefits and have been studied for their anti-cancer, antimicrobial, antioxidant, antiparasitic, and antiviral activities, as well as their ability to regulate blood glucose.

Anthocyanins are well-known for their antioxidant properties, as well as giving the berries their red color6; flavonols such as quercetin have antihistamine and anti-inflammatory properties and are considered important in cancer prevention.7 Strawberries also contain a significant amount of proanthocyanidins, a flavonol compound that recently has gained more attention and scientific study. Though grapes (Vitis vinifera), cranberries (Vaccinium macrocarpon), and cacao (Theobroma cacao) are the most well-known common food sources of proanthocyanidins, strawberries contain higher concentrations than both red and green grapes.8 Proanthocyanidins and foods with high levels of the compounds also are being investigated at the in vitro level for their anti-fungal properties, specifically against oral Candida strains.9-11

Historical Uses

The Romans were the first to record medicinal uses of the strawberry, and the practice spread to Greece. The berries were believed to be a cure for gout and helpful for digestive problems.12 During the 16th and 17th centuries, strawberries were cultivated and considered to be part of a healthy diet. Thomas Culpeper, a medieval herbalist, noted that strawberries were “singularly good for the healing of many ills,” and while the leaves were the primary plant part used in medicinal preparations, Carl Linnaeus recorded and reportedly proved the efficacy of the berries as a treatment for rheumatic gout.13 The leaves are mildly diuretic and astringent due to their high tannin content and have been used as a laxative.14

The leaves, fruit, crowns, and roots were used in the preparations of ointments, medicinal teas, and syrups.12 The pulp and juice of the berry were also used in cosmetic preparations, including treatments for teeth whitening, skin whitening, and healing sunburns.13 Today the plant is rarely used medicinally; however, a tea prepared from the leaves is used to treat diarrhea and dysentery. Currently, strawberries enjoy widespread popularity and use as a food. The berries are used in baked goods, desserts, ice cream, pies, gelatin desserts, soft drinks, jellies, syrups, and in the production of wines and liquors.15

Modern Research

The consumption of fruits and vegetables abundant in bioactive compounds and antioxidants —  including topical skin application of polyphenols from a variety of dietary sources — has been shown to have a role in the prevention of numerous diseases including skin pathologies, different types of cancer, cardiovascular disorders, as well as age-related degenerative conditions.16 Recent animal studies have shown a potential role of strawberry consumption in improving the aging process, reducing oxidative damage, and improving antioxidant defense.17,18

Other recent in vivo studies have shown positive dietary polyphenol effects including prevention of gastric cancer progression, reduction of inflammation, improvement of plasma lipid profile, reduction of myocardial infarction risk, and increased plasma antioxidant capacity.19,20 Human studies examining polyphenol supplementation have shown that the consumption of 300 g of fresh strawberries significantly enhanced the total antioxidant capacity and serum vitamin C concentration in young, healthy patients.21 One human study showed that an elevated anthocyanin intake, such as the anthocyanins present in strawberries, reduced the risk of myocardial infarction in young and middle-aged women.22 Another human study with young, healthy volunteers consuming 500 g of strawberries daily for one month showed a reduction in triglyceride levels, LDL cholesterol, and total cholesterol.23 The berry’s anthocyanin and dietary fiber content were thought to contribute to this result. However, the average serving size of strawberries is approximately 100 g, making the whole-fruit approach of the previous studies difficult to control and impractical to implement. A similar, placebo-controlled study examined the effect of freeze-dried strawberry powder in drink form on overweight adults and showed a similar trend toward the reduction of LDL cholesterol.24

Nutrient Profile25

Macronutrient Profile: (Per 100 g strawberries)

32 calories

0.67 g protein
7.7 g carbohydrate
0.3 g fat

Secondary Metabolites: (Per 100 g strawberries)

Excellent source of:

Vitamin C: 58.8 mg (98% DV)

Manganese: 0.56 mg (28% DV)

Good source of:

Dietary Fiber: 2 g (8% DV)

Folate: 24 mcg (6% DV)

Also, provides:

Potassium: 153 mg (4.4% DV)

Magnesium: 13 mg (3.3% DV)
Vitamin K: 2.2 mcg (2.8% DV)
Vitamin B6: 0.05 mg (2.5%DV)
Phosphorus: 24 mg (2.4% DV)
Niacin: 0.39 mg (2% DV)
Calcium: 16 mg (1.6% DV)
Thiamin: 0.02 mg (1.3% DV)

DV = Daily Value as established by the US Food and Drug Administration, based on a 2,000-calorie diet.


Recipe: Strawberry-Avocado Salsa

Ingredients:

  • 1 cup fresh strawberries, finely chopped
  • 1/2 large avocado, slightly firm, finely chopped
  • 2 tablespoons red onion, finely chopped
  • 2 tablespoons fresh cilantro, chopped
  • 1 teaspoon grated lime zest
  • 2 tablespoons freshly squeezed lime juice
  • 1 large jalapeño pepper, seeded and minced
  • 1/4 teaspoon sugar

Directions:

  1. Combine all ingredients in a bowl and stir gently to combine. Serve with fish, chicken, or pork, or enjoy as a dip with tortilla or pita chips.

References

  1. Holmes R. Taylor’s Guide to Fruits and Berries. New York, NY: Houghton Mifflin Company; 1996.
  2. Madison D. Edible: An Illustrated Guide to the World’s Food Plants. Washington, DC: National Geographic Society; 2008.
  3. Murray M. The Encyclopedia of Healing Foods. New York, NY: Atria Books; 2005.
  4. Shopper’s Guide to Pesticides. Environmental Working Group website. Available here. Accessed April 20, 2015.
  5. Aaby K, Mazur S, Nes A, Skrede G. Phenolic compounds in strawberry (Fragaria ananassa Duch.) fruits: Composition in 27 cultivars and changes during ripening. Food Chemistry. May 2012;132(1):86-97.
  6. Lila MA. Anthocyanins and human health: An in vitro investigative approach. J Biomed Biotechnol. 2004(5):306-313.
  7. Steven D. Quercetin. University of Maryland Medical Center website. Available here. Accessed April 15, 2015.
  8. Liwei G, Kelm MA, Hammerstone JF, et al. Concentrations of proanthocyanidins in common foods and estimations of normal consumption. J Nutr. 2004;134(3):613-617.
  9. Rane HS, Bernardo SM, Howell AB, Lee SA. Cranberry-derived proanthocyanidins prevent the formation of Candida albicans biofilms in artificial urine through biofilm- and adherence-specific mechanisms. J Antimicrob Chemother. 2014;69(2):428-436.
  10. Feldman M, Tanabe S, Howell A, Grenier D. Cranberry proanthocyanidins inhibit the adherence properties of Candida albicans and cytokine secretion by oral epithelial cells. BMC Complement Altern Med. 2012;12:6.
  11. Patel KD, Scarano FJ, Kondo M, Hurta RA, Neto CC. Proanthocyanidin-rich extracts from cranberry fruit (Vaccinium macrocarpon Ait.) selectively inhibit the growth of human pathogenic fungi Candida spp. and Cryptococcus neoformans. J Agric Food Chem. 2011;59(24):12864-12873.
  12. Darrow G. The Strawberry History, Breeding, and Physiology. New York, NY: Holt, Rinehart, and Winston; 1996.
  13. Grieve M. Strawberry. A Modern Herbal. 1931. Available here. Accessed April 15, 2015.
  14. Li T. Vegetables and Fruits: Nutritional and Therapeutic Values. Boca Raton, FL: CRC Press; 2008.
  15. Ensminger A, Ensminger M, Konlande J, Robson J. The Concise Encyclopedia of Foods & Nutrition. Boca Raton, FL: CRC Press; 1995.
  16. Giampieri F, Alvarez-Suarez J, Battino M. Strawberry and human health: effects beyond antioxidant activity. J Agric Food Chem. 2014;62(18):3867–3876.
  17. Charles A, Meyer A, Geny B, et al. Polyphenols prevent aging-related impairment in skeletal muscle mitochondrial function through decreased reactive oxygen species production. Experimental Physiology. February 2013;98(2):536-545.
  18. Laurent C, Chabi B, Feillet-Coudray C, et al. Polyphenols decreased liver NADPH oxidase activity, increased muscle mitochondrial biogenesis and decreased gastrocnemius age-dependent autophagy in aged rats. Free Radical Research. September 2012;46(9):1140-1149.
  19. Alvarez-Suarez J, Dekanski D, Battino M, et al. Strawberry polyphenols attenuate ethanol-induced gastric lesions in rats by activation of antioxidant enzymes and attenuation of MDA increase. Plos ONE. October 2011;6(10):1-11.
  20. Kim J, Kim K, Baik S, et al. Anthocyanins from black soybean inhibit Helicobacter pylori-induced inflammation in human gastric epithelial AGS cells. Microbiology and Immunology. May 2013;57(5):366-373.
  21. Azzini E, Intorre F, Maiani G, et al. Absorption of strawberry phytochemicals and antioxidant status changes in humans. Journal of Berry Research. 2010;1(2):81-89.
  22. Cassidy A, Mukamal K, Liu L, Franz M, Eliassen A, Rimm E. High anthocyanin intake is associated with a reduced risk of myocardial infarction in young and middle-aged women. Circulation. January 2013;127(2):188-196.
  23. Alvarez-Suarez J, Giampieri F, Battino M, et al. One-month strawberry-rich anthocyanin supplementation ameliorates cardiovascular risk, oxidative stress markers and platelet activation in humans. Journal of Nutritional Biochemistry. March 2014;25(3):289-294.
  24. Basu A, Betts NM, Nguyen A, Newman ED, Fu D, Lyons TJ. Freeze-dried strawberries lower serum cholesterol and lipid peroxidation in adults with abdominal adiposity and elevated serum lipids. J Nutr. 2014;144(6):830-837.