This Nutrient Found in Vegetables Protects Eyes and Enhances Cognitive Ability

Save

4/11/2023

Updated:

4/18/2023

0:00

The pigments that give color to fruits and vegetables are complex compounds with notable effects on human health. Among these pigments, lutein is of particular significance to the eyes because it’s 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, orange-yellow fruits, and most notably in green leafy vegetables such as kale and spinach. Plants can synthesize lutein, but the human body can only obtain it through eating foods containing lutein.

Lutein intake is therefore dependent on what we eat and will vary greatly according to the dietary habits in any given region. According to a research review published in Nutrients in 2018, research shows that Americans consume an average of 1.7 milligrams of lutein per day, while in Korea, it’s about three milligrams. In contrast, in Fiji, where people eat a lot of fruits and vegetables, it peaks at about 25 milligrams per day.

Lutein can effectively absorb blue light and can therefore protect the eyes and skin from oxidative damage caused by sunlight. For those who are stuck on the computer for several hours per day, lutein might be the 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. Free radicals are the bad boys of human molecular biology. They can play an important role in immune function, but there are almost always too many of them running rampant in the body, creating all kinds of problems from accelerated aging to an increased risk of cancer and other diseases.

Lutein is a type of law enforcer, helping to neutralize free radicals and reduce their damage.

Beneficial Effects of Lutein

Various studies have found that lutein has several 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’s 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 eating more 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.

2. Prevents Dementia

In recent years, a growing number of studies have 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 normal cognitive function were significantly higher than that in the brains of those with cognitive impairment.

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, such as cardiovascular disease, 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 a greater distance than rats that weren’t supplemented. 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

Lutein is commonly found in vegetables and fruits, especially green leafy vegetables and plant foods that are yellow or orange in color, such as carrots, squash, corn, and citrus. Egg yolks are also a great source of lutein and zeaxanthin.

Lutein and Zeaxanthin Content in Common Raw Foods (per 100-gram or 3.5-ounces)

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

3 Risks of Excessive Intake

When it comes to lutein, more isn’t always better. The recommended daily intake of lutein varies from person to person. Studies have found that a daily intake of six milligrams of lutein can prevent age-related macular degeneration, and a daily intake below 20 milligrams is generally safe, but excessive intake may cause some negative effects on the body. An overly large intake of lutein may lead to:

Skin pigmentation
Darkening of skin tone or lip color
Affected absorption and metabolism of some drugs

When using lutein supplements, one should follow the manufacturer’s directions and avoid excessive intake. For pregnant women, infants, and people with specific diseases, among others, it’s best to consult a specialist physician or nutritionist to determine the appropriate amount.

The health benefits of lutein are manifold, from eye health to cardiovascular health and may even include fighting cancer. However, some studies have been inconclusive, 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 are an important ingredient of a healthy diet.