Good nutrition is important to keep your eyes healthy and functioning their best throughout your lifetime. Two very important eye nutrients that may reduce your risk for macular degeneration and cataracts are lutein (LOO-teen) and zeaxanthin (zee-ah-ZAN-thin). Lutein and zeaxanthin are two types of carotenoids , which are yellow to red pigments found widely in vegetables and other plants.
In nature, lutein and zeaxanthin appear to absorb excess light energy to prevent damage to plants from too much sunlight, especially from high-energy light rays called blue light.
n addition to being found in many green leafy plants and colourful fruits and vegetables, lutein and zeaxanthin are found in high concentrations in the macula of the human eye, giving the macula its yellowish colour. Recent research has discovered a third carotenoid in the macula. Called meso-zeaxanthin, this pigment is not found in food sources and appears to be created in the retina from ingested lutein.
Eye Benefits of Lutein and Zeaxanthin
Lutein and zeaxanthin appear to have important antioxidant functions in the body. Along with other natural antioxidants, including vitamin C, beta-carotene and vitamin E, these important pigments guard the body from damaging effects of free radicals, which are unstable molecules that can destroy cells and play a role in many diseases.
It is believed that lutein, zeaxanthin and meso-zeaxanthin in the macula block blue light from reaching the underlying structures in the retina, thereby reducing the risk of light-induced oxidative damage that could lead to macular degeneration (AMD). A number of studies have found that lutein and zeaxanthin either help prevent AMD or may slow progression of the disease:
- Research published in Nutrition & Metabolism found that a nutritional supplement containing meso-zeaxanthin, lutein and zeaxanthin effectively increased the optical density of the macular pigment in eyes of the majority of human subjects. The macular pigment is believed to offer protection against the development of macular degeneration.
- Studies published in American Journal of Epidemiology, Ophthalmology and Archives of Ophthalmology found higher levels of lutein and zeaxanthin in the diet are associated with a lower incidence of AMD.
- Two studies published in Investigative Ophthalmology and Visual Science found that eyes with greater levels of macular pigments were less likely to have or develop macular degeneration.
- In research published in Archives of Biochemistry and Biophysics, the study authors conclude that lutein, zeaxanthin and meso-zeaxanthin filter short-wavelength light and prevent or reduce the generation of free radicals in the retinal pigment epithelium and choroid. They also suggest that a mixture of these carotenoids is more effective than any one of the individual carotenoids at the same total concentration.
- In a study published in the journal Optometry, participants with early AMD who consumed 8 mg per day of dietary zeaxanthin for one year improved their night driving and their visual acuity improved an average of 1.5 lines on an eye chart.
In May 2013, the much-anticipated results of the second large-scale Age-Related Eye Disease Study (AREDS2) sponsored by the National Eye Institute were published. AREDS2 and other studies found evidence that lutein and zeaxanthin play a role in preventing macular degeneration or reducing the risk of progression of the disease. But it is less certain that these carotenoids help prevent cataracts.
AREDS2 was a follow-up to the original 5-year AREDS study published in 2001, which found use of a daily antioxidant supplement containing beta-carotene, vitamin C, vitamin E, zinc and copper reduced the risk of progressive AMD by 25 percent among participants with early and intermediate macular degeneration.
Foods Containing Lutein And Zeaxanthin
The best natural food sources of lutein and zeaxanthin are green leafy vegetables and other green or yellow vegetables. Among these, cooked kale and cooked spinach top the list, according to the U.S. Department of Agriculture (USDA).
We haven’t mentioned the plant with the highest lutein content yet because it is not generally grown for food – it is the yellow flowered garden nasturtium (Tropaeolum Majus), which has a peppery taste and both the leaves and flowers can be eaten, perfect for adding some bright colour, lutein and beneficial beta-carotene to your salads!
Animal Study Finds Nutritional Supplements Reduce Risk of Diabetic Retinopathy
Nutritional supplements containing lutein and zeaxanthin, lipoic acid, and omega-3 fatty acids are effective in preventing the development of retinopathy among diabetic rats, according to a study. Researchers at the Kresge Eye Institute in Detroit investigated the effect of carotenoid-containing supplements on retinal oxidative stress and inflammation and the development of diabetic retinopathy.
Diabetes was induced and confirmed in all rats in the study, and then some rats were given a diet that included the nutritional supplements while others were given the same food but without the supplements. After 11 months, the retinas of the rats were evaluated for changes in blood vessels, cellular damage and other retinal changes characteristic of diabetic retinopathy. In rats that had not received the nutritional supplements, diabetes-induced damage to retinal blood vessels was three to four times greater than among rats who had received the added nutrients.
The study authors concluded that the nutritional supplements used in this study prevented diabetic retinopathy and preserved normal retinal functioning. They also said that, though human testing is required to confirm, these supplements “could represent an achievable and inexpensive adjunct therapy” to inhibit diabetic retinopathy in people with diabetes.