Below is an approximation of this video’s audio content. To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video.
Alzheimer’s patients have significantly lower blood levels of eight out of 10 antioxidants investigated––though, of course, this could just be a consequence of demented individuals eating diets poor in fruits and vegetables. When put to the test, the PREADViSE study found no benefit for vitamin E or selenium in terms of preventing dementia. What about other antioxidants? In the Harvard Physician’s Health Study, nearly 6,000 older men were randomized to beta carotene or placebo. No difference was found after three years. But after 15 years, those unknowingly taking the equivalent of 3/4 cup (150 g) of sweet potato worth of beta carotene a day had slightly yet significantly better overall cognitive performance. A similar study of older women found no cognitive benefit over a period of nine years. Maybe they just didn’t wait long enough?
Vitamin E and C were also tested. Vitamin E similarly flopped throughout, and so did vitamin C, up until the last cognitive assessment at around year nine where the vitamin C group appeared to pull ahead. However, two trials of a combination of vitamin C, E, and beta carotene together versus placebo—one randomizing 1,500 older patients for seven years and another truly massive one randomizing more than 20,000 adults for five years—both failed to show any cognitive benefit for the antioxidant cocktail.
What about a multivitamin? The Physician’s Health Study also tested taking the daily multivitamin/multimineral supplement Centrum Silver for 12 years. Compared to those instead randomized to a placebo, the Centrum group experienced no cognitive benefit.
Souvenaid is a nutritional drink containing a patented formulation of nutrients, branded as Fortasyn Connect, specifically designed to help in Alzheimer’s disease. Unfortunately, it doesn’t work. There have been three randomized controlled trials enrolling more than a thousand people, and those taking Souvenaid were no less likely to develop dementia in the first place, and probably it has little or no effect on measures of memory or other thinking skills in both those with mild cognitive impairment or Alzheimer’s disease.
In terms of specific minerals other than the failed selenium, zinc has similarly flopped to improve overall cognition over months or years of supplementation, and it’s possible calcium supplements could make things worse.
Cross-sectionally, those taking calcium have more “hyperintensity” brain lesions on MRI (shown here in red, denoting evidence of mini-strokes) and longitudinally over time, women taking calcium supplements appear to have twice the odds of developing dementia. The Women’s Health Initiative should have been able to settle the question once and for all. Thousands of older women were randomized to calcium supplements (plus vitamin D) or placebo for about eight years. Thankfully, there was no difference in the risk of developing cognitive impairment or dementia. But, that’s what was originally found for heart attack and stroke rates before pre-existing supplement use was taken into account. See, more than half of the women were already taking personal calcium supplements before entering the study and being randomized to calcium or placebo. You can imagine how this could muddy the results. If you just look at the women who weren’t on calcium beforehand, starting calcium resulted in a significant increase in the risk of cardiovascular events, consistent with a meta-analysis of calcium trials showing a 15 percent increase in heart attacks or strokes among those randomized to calcium supplements over placebo. Unfortunately, such a reanalysis has yet to be performed on the dementia data.
The bottom line is that vitamin and mineral supplements probably aren’t going to help prevent dementia or treat it, but there are tons of other things we can do. Preserving your Mind is the largest chapter of my book How Not to Age. Check it out at your local public library or listen to me read it on audiobook. All proceeds I receive from the sales of all my books go to charity.
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