Food as Medicine: Butternut Squash (Cucurbita moschata)

History and Traditional Use

Range and Habitat

Cucurbita moschata— often referred to as winter or pumpkin squash — is a trailing annual with lobed leaves that produce yellow flowers. Mature fruits that are peanut- or bottle-shaped are harvested for their rich orange flesh and edible seeds. Native to tropical and subtropical America, butternut squash requires warmer climates for cultivation as it is intolerant of cold temperatures.

Curcurbita moschata grows best in a rich and well-drained soil in full sun. It can be stored for extended periods and, in fact, has one of the longest shelf lives of the squash family.

Phytochemicals and Constituents

Winter squashes, such as the butternut, are high in complex carbohydrates and provide vitamin C, potassium, iron, riboflavin, and magnesium. Additionally, butternut squash is an excellent source of vitamin A and carotenoids such as α-carotene, β-carotene, β-cryptoxanthin, lutein, and zeaxanthin, which contribute to its claimed anti-cancer properties. While it is a low-fat food, butternut squash does contain some healthy fats in the form of alpha-linoleic acid, a beneficial omega-3 fatty acid that the body does not produce naturally. Omega-3s possess a variety of health benefits, including anti-inflammatory properties.

The vitamin C retention in butternut squash after cooking is unusually high compared to other vitamin C-containing vegetables, and this is thought to contribute to its potential antioxidant activity. About 80% of the vitamin C in butternut squash is retained after cooking the pulp for 30 minutes at 95°C (203°F). For comparison, cooking degrades vitamin C content in potatoes by 30%, and, after maintaining heat for one hour, levels decrease by another 10%.

Boiled butternut squash has an intermediate glycemic index value at 66 (compared to the reference glucose reference of 100). Despite its relatively high glycemic index value, butternut squash’s complex carbohydrate content slows the breakdown of carbohydrates into simple sugars, thereby delaying the release of insulin.

The edible seeds of the squash, which have nutritional value on their own, can be roasted like pumpkin (C. pepo) seeds. Roasting lightly for a short period of time preserves the healthy oils — including linoleic acid, a polyunsaturated omega-6 fatty acid, and oleic acid, which is plentiful in olive oil — that make up approximately 75% of the fat found in the seeds. Cucurbita moschata seeds contain a higher amount of carotenoids as well as α-, β-, and γ-tocopherol than C. maxima and other pumpkin seeds. The seeds are a good source of vitamin E, which also may contribute to the plant’s antioxidant activity.

Historical Uses

Cucurbita moschata cultivation dates back more than 10,000 years to Central America. The use of the plant spread to the north and south, with evidence of use from 4,900 BCE in southern Mexico and 3,000 BCE in coastal Peru. Centuries later, Christopher Columbus and other European explorers brought squash from the Americas to Europe.

Squash were initially cultivated for their seeds; in early varieties, the sparse flesh was bitter and inedible. Pumpkin or squash seeds have been used for treating enlarged prostate glands and intestinal parasites.

In Traditional Chinese Medicine (TCM), squash seeds have been used since at least the 17th century. TCM practitioners consider squash to be a warming food that aids digestion, improves qi (energy) deficiency in the spleen/pancreas, and alleviates pain. Application of fresh squash juice may reduce inflammation and relieve burns, and its slightly acidic nature led to its incorporation as an ingredient in bone marrow or “longevity” soup. In Ayurveda, winter squash has a history of use to reduce vata (conditions that are dry and cold) and pitta (conditions that are inflammatory and hot). Winter squash are considered therapeutic foods beneficial for diabetics due to their complex carbohydrate content.

Modern Research

Butternut squash pulp produced as a byproduct of the manufacturing process is thought to be a potential source for the production of prebiotics used in functional food and nutraceutical products. In 2010, butternut squash pulp oligosaccharides were analyzed to determine their potential for prebiotic production. Prebiotics must withstand digestion to ultimately reach the colon and stimulate the growth of bacteria or microbiota. The oligosaccharides demonstrated resistance to hydrolysis by artificial human gastric juice and α-amylase when compared to inulin, a reference prebiotic. These oligosaccharides also stimulated the growth of lactobacilli in comparison to inulin.

Research on the therapeutic properties of butternut squash has been limited to human cell studies and animal studies. Analyses of bioactive compounds have focused on cucurmosin, which has been isolated from the fleshy part of the fruit. Cucurmosin inhibits the proliferation of cancer cells by inducing apoptosis (programmed cell death). A 2012 study showed that cucurmosin inhibits cell proliferation in a time- and dose-dependent manner and induces apoptosis specifically in human pancreatic cancer BxPC-3 cells. Cucurmosin down-regulates, or decreases the quantity of, epidermal growth factor receptor (EGFR) protein expression, which is associated with overexpression that may promote pancreatic tumor growth and metastasis. Researchers also found that cucurmosin inactivated the PI3K/Akt/mTOR signaling pathway in human pancreatic cancer cells.

In a separate study, human liver carcinoma cells (HepG2 cells) were treated with cucurmosin, which resulted in an increase of cell apoptosis in a concentration-dependent manner. Additional studies, particularly human clinical trials, are needed to assess the potential therapeutic potential of butternut squash in greater detail.

Nutrient Profile


Macronutrient Profile:
(Per 1 cup raw butternut squash cubes)

Calories: 63
Protein: 1.4 g
Carbohydrates: 16.4 g
Fat: 0.14 g

Secondary Metabolites: (Per 1 cup raw butternut squash cubes)

Excellent source of:

Vitamin A: 14,882 IU (298% DV)
Vitamin C: 29.4 mg (49% DV)

Very good source of:

Manganese: 0.38 mg (19% DV)
Potassium: 493 mg (14% DV)
Magnesium: 48 mg (12% DV)
Vitamin B6: 0.22 mg (11%DV)
Dietary Fiber: 2.8 g (11% DV)

Good source of:

Folate: 38 mcg (9.5% DV)
Thiamin: 0.14 mg (9.3% DV)
Niacin: 1.68 mg (8.4% DV)
Phosphorus: 46 mg (4.6% DV)
Vitamin K: 1.5 mcg (1.9% DV)
Riboflavin: 0.03 mg (1.8% DV)

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


Recipe: Creamy Butternut Squash Soup

Courtesy of Sarah Edwards

Ingredients:

  • 1 whole head of garlic, cloves separated and peeled
  • 2 medium butternut squash
  • 2 medium carrots, peeled and chopped
  • 1 medium onion, peeled and quartered
  • 4 tablespoons of extra virgin olive oil
  • 1 teaspoon salt
  • 8 cups vegetable broth
  • 2 teaspoons of freshly minced ginger
  • 1/8 cup coconut milk (or more, to taste)
  • 1 bunch cilantro, chopped (for garnish)

Directions:

  1. Preheat oven to 350°F. Slice butternut squash in half, peel, and scoop out the seeds.
  2. Cut off the bulbous ends where the seeds have been scooped out and place peeled whole cloves of garlic in each cavity. Place squash face down in a large baking dish.
  3. Peel and cut the rest of the squash into large cubes and place in the baking dish with onion and carrot. Drizzle with olive oil and season with salt. Roast for 1 hour until tender.
  4. Heat broth in a large pot over medium heat. Add the butternut squash sections and garlic into the saucepan along with the roasted vegetables and minced ginger, then bring to a boil and simmer for 10 minutes.
  5. Stir in the coconut milk and allow to cool slightly. Blend the soup in batches in a blender or in the pot with an immersion blender until thick and creamy. Garnish with cilantro or roasted butternut squash seeds.
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