This Nutrient Found in Vegetables Protects Eyes and Enhances Cognitive Ability

Colorful vegetables and fruits are rich in pigments. Among these pigments, lutein is of particular importance to the eyes because it is an important component of the macula within the retina. For the elderly, supplementing lutein not only helps prevent cataracts and macular degeneration but also improves cognitive ability and mobility.

Lutein is found in egg yolks and in many fruits and vegetables, most notably green leafy ones such as kale and spinach. Plants can synthesize lutein but the human body cannot, and can only obtain it through the intake of foods containing lutein.

Lutein intake is therefore dependent on vegetable intake, and will also vary greatly in different countries according to the prevalent eating habits. According to a 2018 Nutrients article, statistics show that most Americans, who follow a Western-style diet, consume an average of 1.7 milligrams of lutein per day, while in countries that prefer a Mediterranean diet, the amount ranges from 1.07 to 2.9 milligrams a day. In Korea, it is about 3 milligrams. In contrast, Fiji Islanders peak at about 25 milligrams a day.

Lutein can effectively absorb blue light and can therefore protect the eyes and skin from oxidative damage caused by sunlight. For those who claim they can’t stay away from the computer for even a single minute within a day, lutein might be their best friend and a secret weapon to shield themselves from blue light radiation.

Lutein is also a powerful antioxidant that can help the body fight free radicals, prevent chronic diseases, and promote the normal functioning of the immune system. Put in a more familiar context, free radicals are a type of “criminal element” doing all the harm in human aging and increasing the risk of cancer and other diseases, while lutein is a type of “law enforcer,” helping to neutralize the former and reducing their damage on the human body.

Beneficial Effects of Lutein

Various studies have found that lutein has the following beneficial effects.

1. Protects Eyesight

Lutein belongs to the carotenoid family. Although there are about 700 different carotenoids in nature, only some 20 carotenoids including alpha-carotene, beta-carotene, gamma-carotene, lutein, and zeaxanthin can be absorbed by the human body and enter the bloodstream. Of these, only two from dietary sources, lutein and zeaxanthin, can ultimately reach as far as the retina. According to a paper in Clinics in Dermatology, these two carotenoids are found in the eye tissue where they accumulate in the center of the retina and make up the macular pigment.

So what is a macular pigment? It exists mainly in the macula area of the human eye, which can absorb and neutralize the high-energy blue light and ultraviolet rays in the electromagnetic spectrum, thereby protecting the retina from light damage.

Many studies have proved the importance of lutein and its isomers in vision. A study of more than 40,000 participants found that increasing dietary intake of lutein and zeaxanthin significantly reduced the risk of developing cataracts in older adults and reduced the chance of blindness.

An over-20-year study in the United States found that increasing the diet content of a variety of carotenoid-rich fruits and vegetables may reduce the incidence of advanced age-related macular degeneration.

For patients with age-related macular degeneration, taking lutein supplements for 36 months can improve the symptoms, according to the U.S. National Library of Medicine website.

2. Prevents Dementia

In recent years, a growing number of scientific research has found that lutein intake is also associated with other positive health markers, including improved cognitive function. Those studies found that lutein concentrations in the brains of older adults with cognitive impairment were significantly lower compared to those with normal cognitive function.

For young people, supplementing with lutein can also help improve cognitive function. A randomized, double-blind controlled trial found that healthy young adults who took lutein and zeaxanthin supplements for one year had significantly improved test results of their cognitive ability, including spatial memory and reasoning ability, compared with the placebo control group.

3. Prevents Cancer and Cardiovascular Disease

Lutein can also reduce the risk of chronic diseases, like cardiovascular disease (CVD), cancer, and others because it helps reduce oxidative and inflammatory responses in vascular endothelial cells.

4. Improves Mobility

Lutein supplementation may also improve physical activity. Studies found that rats supplemented with lutein ran more distance than rats that were not. For sedentary older human adults, there was also a statistically positive linear relationship between increases in plasma lutein concentrations and increases in physical activity.

5. Protects the Skin

Lutein has also been found to benefit skin health. Taking lutein-containing nutritional supplements can improve skin elasticity and moisture levels, reduce dry, wrinkled skin, and reduce skin damage caused by UV rays, thereby reducing the risk of skin cancer. The basis for these health benefits is lutein’s antioxidant properties that remove free radicals.

How to Take Lutein

Discussing all those benefits of lutein likely makes one curious about its source.

Lutein is commonly found in green vegetables and fruits, especially those yellow or orange, such as carrots, squash, corn, and citrus. In addition, egg yolks are also a great source of lutein and zeaxanthin.

According to the Nutrients article, the following are the lutein and zeaxanthin content in common raw foods (all on a 100-gram or 3.5-ounces basis):

• Spinach: 12.2 milligrams
• Sweet potato leaves: 14.72 milligrams
• Turnip greens: 12.83 milligrams
• Cress: 12.50 milligrams
• Chicory: 10.30 milligrams
• Kale: 6.26 milligrams
• Peas: 2.48 milligrams
• Lettuce: 2.31 milligrams
• Squash: 2.13 milligrams
• Egg yolk: 1.09 milligrams

Although lutein is found in so many vegetables and fruits, ways of cooking and food pairings can also affect its absorption rate. For example, an oily environment can increase the bioavailability of lutein because it is a fat-soluble nutrient. Therefore, it is recommended to cook in the company of foods rich in healthy fats, such as olive oil, avocado, nuts, seeds, and the like, to bring out the best absorption of lutein.

3 Risks of Excessive Intake

When it comes to lutein intake, is the more the better? The recommended daily intake of lutein varies from person to person. Studies have found that a daily intake of 6 milligrams of lutein can prevent age-related macular degeneration, and a daily intake of lutein below 20 milligrams is generally safe. Appropriate intake of lutein generally does not cause obvious adverse reactions, but excessive intake may cause some negative effects on the body. A large intake of lutein may lead to:

1. Skin pigmentation
2. Darkening of skin tone or lip color
3. Affected absorption and metabolism of some drugs

Moderate intake of lutein is considered safe for most people, but when using lutein supplements, one should follow closely the manufacturer’s directions for use and try to avoid excessive intake. For pregnant women, infants, and people with specific diseases, among others, it is best to consult a specialist physician or nutritionist to determine the appropriate intake amount.

The health benefits of lutein are manifold, from eye health to cardiovascular health, and may even be effective in fighting cancer. However, some studies have not yet been completely conclusive, and more clinical and large-scale randomized, controlled trials are needed to confirm these preliminary results. The available evidence so far suggests that foods containing lutein should be merited as an important ingredient of a healthy diet.