Men who take long-term supplements of beta-carotene - an antioxidant found in carrots and other vegetables -- may enjoy less cognitive decline, according to a US study published Monday.
The study led by Francine Grodstein, of Brigham and Women's Hospital and Harvard Medical School, could have implications for the prevention of Alzheimer's and other debilitating mental conditions. Beta-carotene, which gives carrots their orange colour, is broken down by the liver to become a form of vitamin A and is also helpful against damage caused by free radicals. Other sources include spinach, sweet potatoes and coriander.
Grodstein's team, according to a report in the Archives of Internal Medicine, studied the effects of beta-carotene on the cognitive ability of two groups of men.
A long-term group comprised 4,052 men who in 1982 had been randomly assigned to take a placebo or 50 milligrams of beta-carotene every other day. Between 1998 and 2001, 1,904 men were also given placebos or the supplement to see its effects over a shorter run.
Men in the short-term group displayed no differences in cognition regardless of whether they took beta-carotene or the placebo.
"But men in the long-term group who took beta-carotene had significantly higher scores on several of the cognitive tests compared with men who took placebo," the report said. The authors wrote that "very modest differences in cognition, especially verbal memory, predict substantial differences in eventual risk of dementia."
"Thus, the public health impact of long-term beta-carotene use could be large."
But in an accompanying article, Kristine Yaffe of the San Francisco VA Medical Center and University of California, San Francisco, wrote that other explanations could exist for beta-carotene's apparent neurological benefits. "Furthermore, there is new concern that high-dose antioxidant supplementation, including beta-carotene, may have adverse health consequences including mortality," she said. Grodstein's team acknowledged that beta-carotene was not without risks, citing a higher risk of lung cancer in smokers.
"However, its benefits against dementia surpassed those of other medications tested in healthy older people. Thus, the public health value of beta-carotene supplementation merits careful evaluation," the authors concluded.