B Vitamins Can Reduce Brain Shrinkage and Slow Dementia in Cases of Mild Cognitive Impairment, (MCI)

High daily doses of B-6, B-12 and folic acid can cut the rate of brain shrinkage in half in older people with cognitive decline, according to a newly released two-year clinical trial done by scientists at Oxford University. Vitamin B supplementation could also slow down the progression toward dementia in folks with mild cognitive impairment, (MCI) the researchers found.1

This makes perfect sense because these B vitamins are co-factors for the enzymes involved in the metabolism of homocysteine. Homocysteine is an amino acid in the blood, and is a major risk factor for brain atrophy, cognitive impairment, dementia and coronary artery disease. Ultimately plasma concentrations of homocysteine are determined by your vitamin B status.2

An earlier report from scientists at Boston University showed that people with elevated levels of homocysteine in the blood (levels above 14 micromoles per liter of serum) had nearly double the risk of developing Alzheimer’s disease (AD). That study of a group of people participating in the long-running Framingham Study appeared in the February 14, 2002, issue of The New England Journal of Medicine, and was the first to tie homocysteine levels measured several years before with later diagnosis of AD and other dementias.3

In an interview with Reuters News, the scientists from Oxford University said their recent two-year clinical trial was the largest to date into the effect of B vitamins on MCI.4

What is Mild Cognitive Impairment?

Mild cognitive impairment is defined as cognitive decline greater than expected for an individual’s age and education level. MCI affects between 3% to 19% adults older than 65 years, and manifests as slight problems with memory loss, language, arithmetic, and other mental functions. MCI is defined as not interfering with normal daily life, but if you can’t remember where you parked your car, or how to figure out a tip on a restaurant bill, then it definitely is going to impact your life somewhat.

Some people with mild cognitive impairment seem to remain stable or return to normal over time, but more than half develop dementia—usually of the Alzheimer’s type—within 5 years.5  And contrary to the misconception that Alzheimer’s is just severe memory loss, it is in fact a terminal disease.

The Oxford Study

This two-year study included 168 volunteers with MCI who were given either a placebo or a daily nutritional supplement containing very high doses of folic acid (0.8mg), vitamin B6 (20mg) and vitamin B12 (0.5mg), or a placebo.1

Brain scans with an MRI were taken at the beginning and end of the trial to measure the rate of brain atrophy. The results, published in the Public Library of Science (PLoS) One journal, showed that on average the brains of those taking the vitamin treatment shrank at a rate of 0.76 percent a year, while those taking the placebo had average brain shrinkage of 1.08 percent.1

People who had the highest levels of homocysteine at the start of the trial benefited the most from the treatment, with their brains shrinking at half the rate of those on the placebo.4

It’s important to note that the vitamins given during the trial were given in extremely high doses. The pills contained approximately 300 times the recommended daily intake of B12, four times daily advised folate levels and 15 times the recommended amount of B6.

Although the trial was not designed to measure cognitive ability, the researchers found those people who had lowest rates of shrinkage had the highest scores in mental tests.4

This study is significant and lends hope for the millions of people around the world who are at risk for developing mild cognitive impairment and Alzheimer’s disease.


  1. Smith AD, Smith SM, de Jager CA, Whitbread P, Johnston C, Agacinski G, Oulhaj A, Bradley KM, Jacoby R, Refsum H. Homocysteine-lowering by B vitamins slows the rate of accelerated brain atrophy in mild cognitive impairment: a randomized controlled trial. PLoS One. 2010 Sep 8;5(9). pii: e12244.
  2. Dinavahi R, Bonita Falkner B. Homocysteine metabolism.
  3. National Institutes of Health news release.
  4. Kelland, K. “B vitamins found to halve brain shrinkage in old.” Reuters Health Information. Medline Plus.
  5. Gauthier S, Reisberg B, Zaudig M, Petersen RC, Ritchie K, Broich K, Belleville S, Brodaty H, Bennett D, Chertkow H, Cummings JL, de Leon M, Feldman H, Ganguli M, Hampel H, Scheltens P, Tierney MC, Whitehouse P, Winblad B; International Psychogeriatric Association Expert Conference on mild cognitive impairment. Mild cognitive impairment. Lancet. 2006 Apr 15;367(9518):1262-70.