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What is Zeaxanthin? + Side Effects

Views: 5475
Reviewed by Nymark M, PhD on November 2, 2016

Zeaxanthin is an antioxidant pigment that gives a lot of vegetables and fruits their distinctive taste and color. It is a yellow pigment that is usually found in egg yolk, tangerine, orange pepper, orange, saffron, and sweet corn. In other vegetables and fruits, the impact of zeaxanthin is less obvious. These include Brussels sprouts, Swiss chard, English peas, kiwi, zucchini, romaine lettuce, collard greens, kale, turnip greens, goji berries, and paprika, for instance.

Interestingly, zeaxanthin is very important for the eyesight. Within the retina, it is responsible for the absorption of ultraviolet light. Without it, the retina would become damaged. Violaxanthin, a dark blue pigment, absorbs UV rays, converting them into reddish pigments known as antheraxanthin. This is then converted into zeaxanthin, which is yellow in color. Together, light energy is absorbed in full. The eye’s enzymes can then convert it back into antheraxanthin, starting the cycle again.

Zeaxanthin and Lutein

Zeaxanthin and lutein are closely related. Lutein is yellow to red in color, depending on its concentration. It absorbs ultraviolet, violet, and blue light. It is found in high concentrations on the retina’s outer edges. Zeaxanthin is found mainly in the middle. Both substances are fat, not water soluble. To absorb them naturally, therefore, a little bit of fat should also be consumed. Interestingly, cooking the fruits and vegetables that contain zeaxanthin and lutein increases their nutritional content.

The Importance of Zeaxanthin for Eye Health

Both zeaxanthin and lutein are needed to protect the eyes, which is why they are generally found together. Absorbed at the same time, they reach the eyes together and start to work at providing protection. Taking only one of the two would not be as effective. You must also take vitamin E, vitamin C, and beta carotene to recharge them.

Zeaxanthin and Age-Related Macular Degeneration (AMD)

When put together, zeaxanthin and lutein help to fight against AMD. The macula is a spot in the center of the retina, oval in shape with yellow color. It allows us to see the finer details and the small differences in depth and color. Additionally, most of the ultraviolet light is absorbed here. When the macula is damaged, people start to lose central vision. AMD is actually the leading cause of blindness in this country. Ten percent of people develop it to a certain degree by the time they are 60, and 25% have it when they reach 75.

AMD can happen at any age, but it rarely does before 60. This is why it is called “age-related”. Around 2 million people in this country are registered as blind due to AMD. There are two types of AMD: wet and dry. With dry AMD, the immune system secrets drusen, which are tiny clumps. When people reach 40 they will usually have a few drusen, but these have no effect on vision yet. Slowly, however, the cones and rods of the retina start to get destroyed. However, it is rare for this to measurably affect vision before someone is 60.

With wet AMD, the blood vessels in the retina start leaking. These repair themselves and form scar tissues, stopping the retina from receiving the necessary nutrients and oxygen. This leads to blind spots in a person’s central vision.

Dry AMD slowly progresses to blindness, with some people never becoming fully blind. With wet AMD, however, progression is much faster. It is possible to have dry AMD and for it to become wet AMD when the drusen becomes harder.

It has been scientifically proven that lutein and zeaxanthin protect people from AMD to a certain degree. According to the Eye Disease Case Control Study, those who consumed large quantities of lutein and zeaxanthin had a 57% reduced chance of developing AMD, compared to those who have very low levels of lutein and zeaxanthin (6mg a day compared to 0.5mg a day).

The Age Related Eye Disease Study (AREDS) Research Group found that the risk of wet AMD was reduced by 37% by consuming 3.5mg per day, and the risk of dry AMD by 27%. While supplementation did not help to prevent AMD, when taking beta carotene and vitamin E as well, the chance of developing wet AMD was reduced significantly.

Zeaxanthin and Cataracts

A cataract happens when the lens becomes cloudy, usually due to cross-linking of the eyes’ proteins and their oxidation. It isn’t really understood why cataracts are formed, although a number of factors are believed to play a part:

  • A flaking of the epithelium (the cornea’s outer layer), addressed by zeaxanthin and lutein.
  • An accumulation of spent glutathione antioxidants on the lens, addressed by vitamins C and E.
  • The eyes’ whites, the sclera, no longer being able to properly deliver fluid to the lens.
  • Cross-linking of proteins due to sugar metabolism, stopping light from passing through them.
  • Long UV exposure.

According to the Wilmer Eye Institute, there were some 22 million people in this country aged 40 or over in 2004 who had cataract formation in one eye at least. This equates to 17% of that population group. Around 6 million, or 6%, however, had experienced sight loss. Interestingly, people in India and Africa are more likely to develop cataracts, and the rates are lower in Europe. Cataracts are more common in women than in men, and particularly in those who spend at least seven hours in the sun each day. Interestingly, people who lose their teeth are more likely to develop cataracts as well.

Cataracts usually affect the vision in one eye only, although they can occur in both eyes. When the cataract grows, depth and color perception start to be affected. Some people see halos or double, particularly if it is at the back of the lens. If it is at the center, nearsightedness is generally caused. Cataracts must be diagnosed by physicians, which is done through a simple red light examination, turning cataracts black.

Cataract operations are now routine procedures. In 92% of cases, there are no complications. They are performed on an outpatient basis, with people returning home after two or three hours. Sometimes, the cataract has to be extracted in full, which is usually not possible for the first one to three years after the original cataract surgery.

In the Nurses Health Study, which was a 12 year study in which 77,446 nurses over the age of 45 had participated, intake of zeaxanthin and lutein was monitored. What the study found was that the nurses with the highest concentration of zeaxanthin and lutein consumption had 22% less chance of developing a cataract.

While it is clear, therefore, that there is a positive impact on eye health in people who take zeaxanthin and lutein, it is also important to understand that this alone is not enough. Rather, it is when combined with other vitamins and minerals that the effects of these two nutrients become really noticeable, and for eye disease prevention to be at its strongest. However, do make sure that you speak to a physician before deciding to take any kind of supplement, over the counter or not.