It is very important to have a healthy, balanced diet in order to make sure your eyes remain healthy and can function properly for your entire life. There are two nutrients in particular that are very important for this, and they may also reduce your chance of developing cataracts and age-related macular degeneration (AMD). These two nutrients are lutein and zeaxanthin.
What Are Lutein and Zeaxanthin?
Both nutrients are carotenoids, which are red to yellow pigments that are commonly found in various plants. Lutein is technically a yellow pigment but if it is found in very high concentrations, it appears orange or even red. In natural products, zeaxanthin and lutein seem to absorb excesses of light energy, thereby stopping plants from getting damaged by the sun. They protect against blue light, a high energy ray of light, in particular.
Both nutrients are found in most colorful vegetables and fruits, as well as in green leafy vegetables. They are also found in the human eye’s macula, in very high concentration. This is what makes the macula look somewhat yellow. In fact, the Latin name for the macula is “macula lutea” with “macula” translating as “spot” and “lutea” as “yellow”.
There is a third carotenoid in the macula as well, which scientists have only recently uncovered. This is known as meso-zeaxanthin, which is a pigment that cannot be found in natural products. Rather, it seems that the retina creates it after lutein has been ingested.
Both nutrients are strong antioxidants. They join the ranks, therefore, of vitamin E, beta carotene, and vitamin C. Their role is to ensure that the body is protected from free radicals, which are the molecules that set out to destroy natural cells, leading to the development of various diseases.
Lutein and zeaxanthin play a vital role in the health of our eyes and the clarity of our vision. It is also believed that lutein is important in protecting people from the buildup of arterial fatty deposits, known as atherosclerosis. This is the disease that is responsible for the majority of heart attacks.
Benefits of Zeaxanthin and Lutein for the Eye
Researchers believe that when the three carotenoids (lutein, zeaxanthin, and meso-zeaxanthin) are put together in the eye’s macula, they stop blue light from reaching the retina’s underlying structures. In so doing, they lower the chances of people developing oxidative damage to their eyes, which in turn can lead to age-related macular degeneration (AMD).
There have now been various studies that have demonstrated the importance of lutein and zeaxanthin in the prevention and slowing down of progression of AMD. These include:
- The research published in Nutrition & Metabolism that determined that if supplements contained all three nutrients, the macular pigment’s optical density was effectively increased in most humans. This pigment is important for the prevention of AMD.
- The studies published in the American Journal of Ophthalmology, American Journal of Epidemiology, and Archives of Ophthalmology, which all showed that people who consumed high levels of lutein and zeaxanthin were less likely to have AMD.
- The studies in the Investigative Ophthalmology and Visual Science, which showed that eyes that had more macular pigments were also at less risk of developing AMD.
- The Archives of Biochemistry and Biophysics published a study in which it was demonstrated that the three nutrients provide a short wavelength light filter, thereby preventing or reducing free radical generation, particularly in the choroid and the retinal pigment epithelium. Additionally, scientists suggested that it is better to have all three nutrients, rather than one individually.
- The Optometry journal published a study to show that people who were in the early stages of AMD but took 8mg daily of zeaxanthin for a year had notably improved night vision, as well as overall visual acuity.
- The National Eye Institute has completed the AREDS (Age-Related Eye Disease Study) and the AREDS2, with the latter published in 2013.
About the AREDS2
The AREDS2 followed the AREDS study that was published in 2001 after five years of research. The original study showed that supplement containing vitamin C, beta carotene, zinc, vitamin E, and copper would lower the chance of progressive AMD developing by 25%. However, it also found that the chance of developing lung cancer was increased in past and present smokers. This effect was observed to be linked to the beta carotene, and researchers set about finding an alternative. The alternative they found, which led to the publication of AREDS2, was lutein and zeaxanthin. It showed that this supplement could help lower the risk of AMD progressing by 10% to 25%.
What these studies and others like them have proven is that AMD can be slowed down, or some say even halted, through appropriate supplementation. It isn’t clear, however, if they have similar effects on cataracts. In fact, in AREDS2, no effect was noticed on cataracts. A study published in the Archives of Ophthalmology, on the other hand, suggests that women could be protected from cataracts if their diets contain lutein and zeaxanthin.
How to Find Natural Sources of Lutein and Zeaxanthin
According to the U.S. Department of Agriculture, the best natural sources of lutein and zeaxanthin are green leafy vegetables, and any fruit or vegetables that are yellow or green in color. These include cooked spinach and cooked kale. Egg yolks also contain high levels, giving it its distinct colors. However, egg yolks are not recommended for people with high cholesterol.
Because there seem to be benefits to both heart and eye health, a lot of nutritional agencies have now added lutein and zeaxanthin to their supplement. There are also various eye vitamins, which usually follow the AREDS2 formulation. No recommended daily intake (RDI) or recommended daily allowance (RDA) exist for lutein or zeaxanthin. It is agree, however, that 6mg of lutein should be the minimum. Unfortunately, it is hard to determine an RDI or RDA for these nutrients because they are found in so many natural sources, which means it can be difficult to measure just how much someone has already consumed.
That said, it is not believed that it is possible to consume toxic levels of either nutrient. Sometimes, people can develop carotenemia, which means their skin can become somewhat yellow. This is harmless, fortunately, and not to be confused with jaundice, which indicates a dysfunction in the blood’s bilirubin.
Usually, supplements use marigold flowers for the lutein element and red peppers for the zeaxanthin element. It is very important to choose high quality products with high quality ingredients, from a brand that you know you can trust. This is also because the supplement industry is not regulated by the U.S. Food and Drug Administration. Additionally, while supplementation can be beneficial, it should never replace a healthy diet. Additionally, you should never take any kind of supplementation before first talking to a physician due to possible allergies and drug interactions, or ill effects on any medical condition you may already have. This is true for all supplements and herbal products. Just because something is natural, unfortunately, does not necessarily mean it is also good for you.
Resources and References:
American Optometric Association – Diet & Nutrition for the Eyes (AOA.org)
National Institutes of Health – NIH Study Provides Clarity on Supplements for Protection Against Blinding Eye Disease (NIH.gov)
National Eye Institute – For the Public: What the AREDS2 Means for You (NEI.nih.gov)