Kale Nutrient May Yield Significant Cognitive Benefits

Researchers have found that lutein, a nutrient and organic pigment found in kale, spinach, avocados, and eggs, may be effective in rejuvenating cognitive functions.

The health benefits of green foods, such as kale, spinach, and other leafy vegetables, have long been discussed by nutritionists.

The importance of lutein – a nutrient and organic pigment, or carotenoid, found in a range of foods including kale, carrots, and even eggs – has often been singled out by specialists in recent studies.

New research from the University of Illinois at Urbana-Champaign, in collaboration with the University of Georgia in Athens, has unveiled yet another health benefit of lutein: the ability to counteract cognitive aging.

Lead researcher Dr. Naiman A. Khan, of the Department of Nutritional Sciences at the University of Illinois, and his colleagues published their findings in the journal Frontiers in Aging Neuroscience.

Cognitive aging sets in early

The researchers started from the premise that cognitive aging becomes apparent earlier in life than one might expect.

Previous studies had only monitored cognitive aging in elderly adults, but Dr. Khan and his colleagues wanted to take a different approach.

“As people get older, they experience a typical decline. However, research has shown that this process can start earlier than expected. You can even start to see some differences in the 30s,” says first study author Anne Walk, a postdoctoral researcher also at the University of Illinois.

With this in mind, the researchers recruited 60 adult participants aged between 25 and 45, setting out to investigate whether or not lutein intake can have an impact on cognition.

The researchers explain that lutein is a naturally occurring substance that cannot be synthesized in the human body. This is why it must be absorbed from foods that synthesize it, such as kale and other green leafy vegetables, or else through food supplements.

Once assimilated by the human body, lutein can be detected in brain tissue as well as in the eyes’ retinas, which makes the appraisal of lutein levels more convenient, as non-invasive measurements can be taken.

“If lutein can protect against decline, we should encourage people to consume lutein-rich foods at a point in their lives when it has maximum benefit,” says Walk.

More lutein improves cognitive performance

On this occasion, the researchers gauged lutein levels in the participants’ eyes by asking them to respond to flickering light stimuli.

The neural activity in the participants’ brains was assessed by electrodes attached to the scalp, as each participant was tasked with an attention-related exercise designed to test their selective attention, attentional inhibition (the ability to ignore irrelevant stimuli), or response inhibition (the ability to suppress inappropriate impulses).

Dr. Khan and colleagues found that the participants who exhibited higher levels of lutein were cognitively more similar to younger individuals than they were to individuals of the same age with lower lutein levels.

“The neuro-electrical signature of older participants with higher levels of lutein looked much more like their younger counterparts than their peers with less lutein. Lutein appears to have some protective role since the data suggest that those with more lutein were able to engage more cognitive resources to complete the task,” explains Walk.

Following this study, the researchers seek to gain a better understanding of how a larger lutein intake might impact the level of the carotenoid accumulated in the retina, and to what extent lutein levels actually influence cognitive capacity.

“In this study, we focused on attention, but we also would like to understand the effects of lutein on learning and memory,” concludes Dr. Khan.

Benefits of Leafy Greens

We all know the benefits of eating our vegetables. They are full of nutrients that can help protect us from a disease. They are also high in fiber, which fills us up in a healthy, low-calorie sort of way. And if you enjoy eating leafy green vegetables, there may be another important advantage in your future as you age. New research suggests that frequent consumption of leafy greens may lower your risk of developing dementia.

The study, which was conducted at Rush University Medical Center in Chicago, Illinois, found that eating one serving a day of a leafy green vegetable may help prevent the onset of dementia as we age. The subjects were 954 men and women who were taking part in a Memory and Aging Project at Rush. They had an average age of 81 at the beginning of the trial, and three-quarters of the group were female.

The participants were followed for an average of nearly five years. Once a year during this time period, they answered a survey with 144 questions on their food and beverage consumption. In addition, they completed an annual battery of 19 mental skills tests. The scientists then compiled all of the data to determine the nutrient intake of each volunteer based on the specific types and amounts of food that were eaten every day.

The findings showed that those people who regularly consumed one to two servings of leafy green vegetables on a daily basis had mental faculties more than 10 years younger than those of their counterparts who never ate leafy greens. That’s quite a significant difference since deteriorating cognitive function is a major hallmark of dementia. And these results remained consistent even after a number of potential influences were factored into the data, including age, gender, education level, history of smoking, physical activity levels, and family history of Alzheimer’s disease.

While the research was not designed to prove that leafy greens necessarily cause increases in mental capacity as we age, it did certainly demonstrate the existence of a link. It may be difficult to pinpoint whether there is some advantage to the particular combination of nutrients found in leafy greens that can serve to protect the brain. However, it is likely that the main defense comes from their high levels of vitamin K.

There are two main forms of vitamin K, which are K1 and K2. Vitamin K1 (phylloquinone) is found in green leafy vegetables and makes up about 90 percent of the vitamin K in a typical western diet. Vitamin K2 (menaquinones) makes up about 10 percent of western vitamin K consumption and can be synthesized in the gut by microflora. It is typically found in animal-based foods, including dairy products.

A 2008 study at the Jean Mayer USDA Human Nutrition Research Center at Tufts University in Boston determined that vitamin K1 is most effective at supporting healthy insulin levels. It is also the K1 in the greens that are responsible for the dementia benefit. On the other hand, vitamin K2 plays a vital role in ensuring that calcium stays in the bones and out of the arteries. As suggested in a 2010 study at the German Cancer Research Center in Heidelberg, it may also play a role in inhibiting cancer.

So clearly vitamin K is a nutrient we want to make sure we include in our diets in adequate amounts. Eat up those leafy greens at least once a day. You will consume 531 mcg of vitamin K in ½ cup of cooked kale, 444 mcg in ½ cup of cooked spinach, and 418 mcg in ½ cup of cooked collard greens. What if you simply can’t stand kale, spinach, or collards? You can choose from some of the other sources of vitamin K1 that may require larger servings, but perhaps you will prefer the taste. Some healthy vitamin K1-rich foods include broccoli, Brussels sprouts, and green leaf lettuce. Start putting these items on your daily menu and your brain may benefit greatly as you get older. And don’t forget to include K2 foods in your diet, or take a supplement if your diet is pure vegan.