Information about B Vitamins and Dementia Risk

Although B vitamins have not been proven to prevent dementia, adequate levels of certain B vitamins are necessary for proper memory function. Vitamins B6, B12, and folate (folic acid), in particular, are important in lowering levels of homocysteine—an amino acid linked to heart attacks, strokes, and Alzheimer's disease.

Thiamin (Vitamin B1)

A thiamin deficiency can lead to numerous health problems, such as memory deficits, confusion, and difficulty walking. One of the more common causes of thiamin deficiency is alcoholism. Because alcoholics often fill up on empty calories from alcohol, their diets lack many essential nutrients, one of the most important being thiamin.

If caught in time, a thiamin deficiency can be treated with thiamin supplements, a proper diet, and cessation of alcohol intake.

Vitamins B6, B12, and Folic Acid

Low levels of these three B vitamins can contribute to high blood levels of homocysteine. Several studies have found that older people with high homocysteine levels are at increased risk for cognitive decline and Alzheimer's. In a study reported in Archives of Neurology, researchers assessed the B6, B12, and folic acid intake of 965 people age 65 or older who showed no signs of dementia.

They found that the risk of developing Alzheimer's disease in the future was 50% lower among people with the highest folic acid intake. (In this study, vitamin B6 and B12 levels had no apparent tie to Alzheimer's disease risk.) Whether supplementation with vitamin B6, B12, and folic acid can reduce the risk of dementia remains unclear, but most multivitamins contain enough of these nutrients to keep homocysteine levels in check.

A deficiency of B12 alone can lead to a wide range of problems, including difficulty thinking and walking. As some people get older, they don't produce enough of a substance in the stomach called intrinsic factor, which is necessary for absorption of vitamin B12. In this situation, supplements won't help, and vitamin B12 injections are needed. A simple blood test can identify a vitamin B12 deficiency.

Vitamin D

Several studies have found links between low blood levels of vitamin D (25-hydroxyvitamin D) and dementia. Laboratory evidence suggests that vitamin D plays a role in protecting neurons, supporting brain function, and reducing inflammation.

Although more study is needed to determine whether taking vitamin D supplements could reduce risk of dementia, it makes sense for elderly people to have their vitamin D levels tested and to consider taking vitamin D supplements if they are deficient.

Vitamin D deficiency is common in people over age 60, particularly those who spend little time outdoors. (The body needs sunlight to manufacture vitamin D.)

Low vitamin D levels have been associated with:

  • cardiovascular disease
  • diabetes
  • depression
  • dental cavities
  • periodontal disease
  • osteoporosis

Publication Review By: Peter V. Rabins, M.D., M.P.H.

Published: 08 Mar 2011

Last Modified: 01 Dec 2014