The sale of vitamins and dietary supplements has grown into a $27 billion industry. A recent study by the Centers for Disease Control found a little over half of the adult population in the U.S. takes at least one vitamin or dietary supplement mostly in the form of a multivitamin. Advertisements abound with claims for vitamins, minerals, and herbs to improve the health of every part of the body including the eye.
So can vitamin supplements improve ocular health? As usual, the answer is not so straightforward. First, the eye requires certain vitamins and minerals for it to function properly. For example, vitamin A is necessary for the retina to function properly. Thiamine is necessary for the optic nerve to transmit information from the eye to your brain. However, most of us receive more than enough of these vitamins in our diet. While a minimum amount of vitamins are necessary for proper function, an excess amount does not improve function.
In 2001, the Age-Related Eye Disease Study (AREDS) released their findings detailing the effects of high doses of antioxidants and zinc on patients with age-related macular degeneration and cataracts. The AREDS study was a well designed, prospective, placebo controlled study that followed 3600 people for over 6 years.
The AREDS study found no effect on the development of cataracts. The study found a significant reduction in the progression of macular degeneration in patients with intermediate and advanced macular degeneration. This was great news because until this point there was no treatment for patients with age-related macular degeneration. It is now standard of care to recommend the AREDS formulation of antioxidants and zinc to patients with intermediate and advanced macular degeneration. The study found no benefit for patients with early macular degeneration or no evidence of macular degeneration.
A study called AREDS II was initiated in 2006 and is currently ongoing that will look at the effects of lutein, xanthophylls, and omega-3 fatty acids on patients with macular degeneration. The results have not been released yet, but a smaller study called the Lutein Antioxidant Supplementation Trial (LAST) has demonstrated improvement in 90 patients with age-related macular degeneration taking lutein supplements over the course of one year.
In 2005, data from the Women’s Health Study (WHS) found a correlation of low intake of dietary omega-3 fatty acids among women who reported dry eye syndrome. A small scale but prospective, randomized, placebo controlled and double-masked study published in 2011 in Cornea found increased tear production and volume in 36 patients with dry eye syndrome who supplemented their diet with omega-3 fatty acids. As a result many doctors, including myself, are now recommending omega-3 fatty acid supplements as part of the treatment regimen for patients with dry eye syndrome.
Conclusion: Myth Confirmed
While there is little evidence vitamins and dietary supplements improve vision in patients without any medical problems, in patients with age-related macular degeneration and dry eye syndrome vitamins and supplements have been shown to be helpful. In the care of age-related macular degeneration, vitamins have become the standard of care.