Vitamin C not a dementia preventer

DEAR DR. ROACH: Is there any evidence that high doses of vitamin C have decreased or prevented the risk of Alzheimer’s disease? I ask this question because none of the people I know who have developed Alzheimer’s have been taking high doses of vitamin C daily (4,000 to 6,000 milligrams). So, I wonder if this safe, inexpensive, natural remedy, found in health-food stores, could have stopped these tragedies by preventing atherosclerosis in the brain. — A.S.

ANSWER: Many people have had the same idea, and it has been the subject of scientific study. A recent review of the many studies that have been done shows that a diet rich in vitamin C (and other nutrients) is of benefit in helping prevent dementia (including Alzheimer’s). However, taking supplements, even high-dose supplements, is unlikely to have any additional benefit over a healthy diet. Most of the studies showed no benefit of vitamin C compared with placebo. I don’t recommend vitamin supplementation for the purposes of preventing Alzheimer’s disease.

DEAR DR. ROACH: I was considering getting a DNA test in order to get personalized diet recommendations. It’s very expensive. Do you think it’s worth it? — J.B.

ANSWER: In theory, it’s a great idea. Knowing about our precise genetic makeup might allow for personalized recommendations not only on diet, but also on exercise, medication and medical treatments. But in practice, the science is in its infancy. There are a few genes identified that predict better outcomes with one treatment or another and that can identify metabolism of medications, but for the specific indication of choosing the best diet, I don’t know of any good evidence that the diet recommended by the results of genetic testing has any better outcome than a diet that would be recommended for someone in general.

Until there is solid evidence of benefit, I’d recommend saving your money.