by Dan Roberts
March 14, 2006

Vitamin A in the form of beta-carotene has been found to be ineffective in slowing the progression of maculopathies such as age-related macular degeneration (AMD). This conclusion was derived from a follow-up study derived from the Physicians' Health Study 1, a randomized, double-blind, placebo-controlled trial with 22,071 U.S. male physicians, ages 40 to 84. William Christen, Sc.D., (Brigham and Women's Hospital, Harvard University) led the new study, which was reported in the March 2006 issue of Archives of Ophthalmology.

The original study found neither benefit nor harm from 12 years of supplementation with beta carotene on cancer or cardiovascular disease. Dr. Christen's team recently found that beta-carotene also had no significant effect on development of AMD, advanced maculopathy or maculopathy with or without vision loss.

The landmark age-related eye disease study (AREDS) found that a high-dosage formula of antioxidants and zinc, which included beta-carotene, was effective in slowing the progression of AMD. Beta-carotene, however, was not studied separately. Dr. Christen allows that the supplement might still be indirectly effective when taken in combination with other antioxidants, but that has yet to be researched.

According to Ellen Troyer, MT, MA (Chief Research Officer of Biosyntrx, Inc.), Vitamin A retinol is essential for good vision, wound healing and proper immune function. Too much, however, can compete for lipoprotein transport space with the xanthophyll carotenoids, including lutein and zeaxanthin. Vitamin A retinol has also been shown in some studies to increase lung cancer risk in smokers and ex-smokers. Since the aging process makes it more difficult for beta carotene to convert to Vitamain A retinol, it is important for senior adults to protect themselves against retinol deficiency. This can be safely accomplished, said Troyer, by supplementing with a small amount of retinyl palmitate (aka pro-formed Vitamin A), which attempts to convert to retinol only if there is such a deficiency.

As always, MD Support recommends that patients consult with both their general physicians and eye care specialists before making any significant changes in dietary supplements.

Source reference: Christen WG, et al "Beta Carotene Supplementation and Age-Related Maculopathy in a Randomized Trial of US Physicians" Arch Ophthalmol. 2007; 125: 333-339.