Can B Vitamins Prevent Alzheimer’s?
A high level of homocysteine has been identified as a risk factor for Alzheimer’s disease, according to a study published in the New England Journal of Medicine.1 If this is the case, B vitamins may potentially reduce the possibility of developing Alzheimer’s, since they have been shown to effectively reduce levels of homocysteine in the blood. Homocysteine is a normal breakdown product of dietary protein.
In this new study, 1,092 men and women over age 68, without Alzheimer's disease, had their blood homocysteine levels measured. These people were then followed over an average of eight years and new cases of Alzheimer’s disease were documented.
The people with elevated homocysteine levels in the blood (above 14 ¼mol per liter were found to be nearly twice as likely to develop Alzheimer’s disease symptoms compared with those with lower homocysteine levels. After careful statistical analysis, the researchers concluded that homocysteine elevation was a risk factor independent of other known risk factors for dementia.
High blood levels of homocysteine have been associated with increased risk of many different diseases, including heart attack,2 stroke,3 and miscarriage.4 Homocysteine levels can be measured with a simple blood test that is increasingly being used by physicians as a screening test for heart disease risk. There is currently debate about what homocysteine level should be considered normal, but many doctors suggest starting treatment in people with levels above 11 ¼mol per liter.
Elevated homocysteine levels can be reduced in many people with a daily vitamin B-complex supplement. Specifically, this supplement should include 400 to 1,000 mcg of folic acid, 10 to 50 mg of vitamin B6, and 50 to 300 mcg of vitamin B12, to match amounts used in clinical trials.5 6 Avoiding cigarettes and coffee may help reduce homocysteine levels, as well.7
One major limitation of this study is that it is impossible to conclusively diagnose Alzheimer’s disease in a living person (Alzheimer’s disease can be diagnosed with certainty only by autopsy). Because of this, it is possible that some people with a condition known as vascular dementia, which is caused by multiple tiny strokes, were incorrectly classified as having Alzheimer's disease. As high homocysteine can predispose to stroke, the results may be slightly skewed.
This study does not prove that high homocysteine levels are a cause of Alzheimer’s disease or that taking B vitamins can prevent the disease. Regardless, this new study is another peek at an emerging picture of the long-term health-promoting benefits of B-vitamin supplementation.
1. Seshadri S, Beiser A, Selhub J, et al. Plasma homocysteine as a risk factor for dementia and Alzheimer’s disease. N Engl J Med 2002;346:476–83.
2. Stampfer MJ, Malinow R, Willett WC, et al. A prospective study of plasma homocysteine and risk of myocardial infarction in US physicians. JAMA 1992;268:877–81.
3. Perry IJ, Refsum H, Morris RW, et al. Prospective study of serum total homocysteine concentration and risk of stroke in middle-aged British men. Lancet 1995;346:1395–8.
4. Nelen WL, Blom HJ, Steegers EA, et al. Homocysteine and folate levels as risk factors for recurrent early pregnancy loss. Obstet Gynecol 2000;95:519–24.
5. Ubbink JB, Vermaak WJH, ven der Merwe A, et al. Vitamin requirements for the treatment of hyperhomocysteinemia in humans. J Nutr 1994;124:1927–33.
6. Ubbink JB, Vermaak WJH, van der Merwe A, Becker PJ. Vitamin B-12, vitamin B-6, and folate nutritional status in men with hyperhomocysteinemia. Am J Clin Nutr 1993;57:47–53.
7. Nyg?rd O, Refsum H, Ueland PM, Vollset SE. Major lifestyle determinants of plasma total homocysteine distribution: the Hordaland Homocysteine Study. Am J Clin Nutr 1998;67:263–70.
Matt Brignall, ND, is in practice at the Seattle Cancer Treatment and Wellness Center and at the Evergreen Integrative Medicine Clinic in Kirkland, WA. He specializes in integrative treatment of cancer. He is a contributor to Healthnotes and Healthnotes Newswire.
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