High levels in the blood of a compound called homocysteine have been found in people with Alzheimer's disease, and people with higher levels of homocysteine have been shown to be at increased risk of Alzheimer's disease. Taking folic acid and vitamin B-12 are known to lower levels of homocysteine in the body, so this gave rise to the 'homocysteine hypothesis' that taking B vitamins could reduce the risk of Alzheimer's disease.
Taking B vitamins won't prevent Alzheimer's disease
15 July 2014
Taking B vitamins doesn't slow mental decline as we age, nor is it likely to prevent Alzheimer's disease, conclude Oxford University researchers who have assembled all the best clinical trial data involving 22,000 people to offer a final answer on this debate.