Americans spend billions of dollars each year on vitamins, some of which are eye vitamins. But not all of these products have the ingredients and dosages that have been proven effective in clinical trials.
Researchers have analyzed popular eye vitamins to determine whether their formulas and claims are consistent with scientific findings. They found that some of the top-selling products do not contain identical ingredient dosages to eye vitamin formulas proven effective in clinical trials. In addition, the study found that claims made on the products' promotional materials lack scientific evidence.
The leading cause of blindness among older adults in the United States is age-related macular degeneration (AMD). A specific formula of nutritional supplements is recommended for AMD treatment when the disease is at certain stages. This is based on two landmark clinical trials known as AREDS and AREDS2. These studies found that high doses of antioxidants and zinc could slow the worsening of AMD in those who have intermediate AMD and those with advanced AMD in only one eye. The first study included beta-carotene in its formula but, due to beta-carotene's link to increased risk of lung cancer in smokers, this was replaced with related nutrients lutein and zeaxanthin. The two studies prompted a surge in sales of eye supplements which are marketed as containing the AREDS or AREDS2 formulas.
To test whether the products are consistent with the studies' findings, researchers compared the ingredients in 11 products from the five top-selling brands to the exact formulas proven effective by AREDS and AREDS2.
They found that, while all of the products studied contained the ingredients from the AREDS or AREDS2 formulas:
All 11 of the products' promotional materials contained claims that the supplements "support," "protect," "help" or "promote" vision and eye health, but none had statements specifying that nutritional supplements have only been proven effective in people with specific stages of AMD. There were also no statements clarifying that there is insufficient evidence to support the routine use of nutritional supplements for primary prevention of eye diseases such as AMD and cataracts.
People considering taking eye vitamins should talk with their ophthalmologist about whether these nutritional supplements are right for them.