Men who take beta-carotene supplements for 15 years or longer may have less cognitive decline, according to a report in the November 12 issue of Archives of Internal Medicine, one of the JAMA/Archives journals1.
Decreases in cognitive ability—thinking, learning and memory skills—strongly predict dementia, a growing public health issue, according to background information in the article. Long-term cellular damage from “oxidative stress” may be a major factor in cognitive decline. Some evidence suggests that antioxidant supplements may help preserve cognition, although previous studies have been inconclusive, the authors note.
Francine Grodstein, Sc.D., of Brigham and Women’s Hospital (BWH) and
The long-term participants were treated 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 several of the cognitive tests compared with men who took placebo.
“In this generally healthy population, the extent of protection conferred by long-term treatment appeared modest; nonetheless, studies have established 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,” the authors write.
Beta-carotene is not without risks—for example, it may increase the risk of lung cancer in smokers, the authors note. 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 conclude. “Moreover, as these data support the possibility of successful interventions at early stages of brain aging in well-functioning subjects, investigations of additional agents that might also provide such neuroprotection should be initiated.”
An accompanying editorial2 noted the need for more studies on cognition and aging. Though the results are plausible, other potential explanations exist for beta-carotene’s neuroprotective effects, writes Kristine Yaffe, M.D., of the San Francisco VA Medical Center and
“For the clinician, there is no convincing justification to recommend the use of antioxidant dietary supplements to maintain cognitive performance in cognitively normal adults or in those with mild cognitive impairment,” Dr. Yaffe writes. “Furthermore, there is new concern that high-dose antioxidant supplementation, including beta carotene, may have adverse health consequences including mortality.”
- Arch Intern Med. 2007; 167(20):2184-2190
- Arch Intern Med. 2007;167(20):2167-2168