Long-Term Beta Carotene Use May Protect Against Dementia

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An accompanying editorial in the journal by Dr. Kristine Yaffe, professor of psychiatry, neurology, epidemiology and biostatistics at the University of California, San Francisco, circled warily around the concept of long-term antioxidant supplements. One possibility, Yaffe said, is that someone who remembers to take a supplement for 18 years is in better mental shape to begin with than someone who doesn't. (Grodstein said that compliance had been checked as carefully for the men taking the placebo.)

The idea that long-term use of the supplements is necessary "is certainly plausible, given that the neuropathologic changes underlying clinically significant impairment appear to take years, if not decades," Yaffe wrote. But evidence for that concept would be difficult to obtain, since it would require trials lasting 25 to 30 years, she said.

"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 those with mild cognitive impairment," Yaffe concluded.

The Alzheimer' Association makes no recommendation about antioxidant supplements. Both the American Heart Association and the American Cancer Society say the evidence for supplements is inconclusive and recommend a diet rich in fruits and vegetables.

More information

To learn more about antioxidants, visit the American Heart Association.