Beta-carotene reduces dementia risk in men

Researchers affiliated with the Channing Laboratory at Brigham and Women’s Hospital (BWH) report in the Nov. 12 issue of Archives of Internal Medicine evidence that men who take beta-carotene supplements for 15 years or longer may have less cognitive decline and better verbal memory than those who do not.

“The public health impact of this research could be large,” said lead author Francine Grodstein, an associate professor of medicine at Harvard Medical School and a researcher at BWH. “Other studies have shown that very modest differences in cognition during middle age, especially verbal memory, predict substantial differences in eventual risk of dementia later in life. Long-term beta-carotene use may reduce this risk.”

The researchers explained that long-term cellular damage from oxidative stress may be a major factor in cognitive decline. Some evidence suggests that antioxidant supplements such as beta-carotene may help preserve cognition, although previous studies have been inconclusive.

In this study, Grodstein and colleagues studied beta-carotene supplements and their effect on cognitive ability in two groups of men enrolled in the Physicians’ Health Study II. The long-term group included 4,052 men who in 1982 had been randomly assigned to take placebo or 50 mg. of beta-carotene, equivalent to about five large carrots, every other day. Between 1998 and 2001, an additional 1,904 men were randomly assigned to one of the two groups. Both groups were followed through 2003, completing yearly follow-up questionnaires with information about their health and their compliance with taking the pills. The men were assessed by telephone for cognitive function at least once between 1998 and 2002.

The long-term participants stayed in the study for an average of 18 years and the short-term participants for an average of one year. Men in the short-term group displayed no differences in cognition regardless of whether they took beta-carotene or placebo, but men in the long-term group who took beta-carotene had significantly higher scores on most of the cognitive tests.

Beta-carotene is not without risks though, the researchers noted. For example, the antioxidant may increase the risk of lung cancer in smokers; however, its benefits for memory surpassed those of other medications tested in healthy older people.

“Our research supports the possibility of successful interventions at early stages of brain aging in healthy adults,” concluded Grodstein. “And there’s no reason to believe that beta-carotene supplementation does not carry the same benefit for women as it does men, though this has yet to be tested.”

The National Institutes of Health supported this research.