Thursday 21 January 2016

How Lutein-Rich Foods Impact Vision

Protecting your eyes is just a carrot – or leafy green – away.

Uncooked Baby Carrots
Read on for the best foods for your eyes.
By Karin Hermoni 

Protecting your eyes is just a carrot – or leafy green – away.

The benefits of carrots to eye health are attributed to an important pro-vitamin A carotenoid: beta carotene, an orange pigment in carrots. Emerging evidence points to the importance of another carotenoid to eye health, called lutein. Lutein and its isomer zeaxanthin are yellow pigments that are part of the xanthophyl carotenoid family, and are abundant in green leafy vegetables such as spinach and kale, and in lesser quantities in corn and egg yolks. The human body does not synthesize carotenoids, which is one of the reasons why green vegetables are essential to good nutrition.
In plants, lutein and zeaxanthin help absorb excess light energy, thus preventing damage to the plants. Particularly, these carotenoids protect the plant from high-energy light rays, called blue light, and the oxidative damage that is associated with exposure to excess light. Interestingly, these antioxidant carotenoids have a somewhat similar role in the human eye, protecting it from the harmful effects of blue light and UV rays.

Carotenoids are a group of pigments that are known antioxidants and have been found to have beneficial effects on many processes in our body, contributing to anything from heart health to more resilient skin cells. What differentiates lutein and zeaxanthin is their high concentration in human eyes. In fact, their concentration in the macula is over 1,000-fold more than their concentration in the plasma. This phenomena must happen for a reason…

Indeed, researchers found that lutein protects the eye not only due to its light screening ability, but also as a result of its antioxidant properties. It reduces oxidative damage by directly fighting the dangerous reactive oxygen species, and by enhancing the antioxidant defense mechanism of the macular cells, allowing our eyes to better cope with the oxidative challenges.
Importantly, diets rich in lutein and zeaxanthin appear to have a protective effect against age-related eye diseases such as age-related macular degeneration, or AMD, and cataracts. Today, there are techniques that allow for more accurate and non-invasive measurements of macular pigments.

Utilizing this technology, epidemiologic studies show an inverse association between macular pigmentation (levels of lutein and zeaxanthin in eye tissues) and age-related degenerative diseases.
A major study called AREDS2 (Age-Related Eye Disease Study 2) examined the effects of a supplement, containing a combination of lutein zeaxanthin with other vitamins and minerals, on the progression of AMD. This five-year multi-center study was the continuation of the first ARED trial that previously studied a slightly different supplement. Both studies were conducted by a research group from the National Institutes of Health's National Eye Institute. The conclusions of these studies revealed a significant effect of the supplement in reducing the rate of advanced AMD in people, those who were at a high risk, by about 25 percent.

The AREDS 2 supplement contained high levels of lutein and zeaxanthin (10 milligrams of lutein and 2 mg of zeaxanthin a day), combined with vitamin C, vitamin E, zinc and copper. The combination of these ingredients is important, but one should also reflect on the importance of a diverse diet. Of note, American dietary intake of lutein/zeaxantin is about 10 times less than the dose found in the stud. So if you're at high risk of developing advanced AMD, you might want to consider taking a supplement. Luckily, there are various AREDS-based supplements in the market today.
Overall, the take-home message is that a diverse and balanced diet containing lutein, as well as other phytonutrients, can greatly support our eye health and protect us from age-related eye diseases. In fact, a healthy diet and healthy lifestyle are important not only to our eye health; they are the key to our general well-being.

Lutein-rich foods:
  • Kale (1 cup): 23.8 mg
  • Spinach (1 cup): 20.4 mg
  • Corn (1 cup): 2.2 mg
  • Broccoli (1 cup): 1.6 mg
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