A new study suggests high doses of B vitamins are associated with halving the rate of brain shrinkage in older people experiencing signs of memory decline.
Brain shrinkage is one of the symptoms of mild cognitive impairment, which often leads to Alzheimer's and other forms of dementia.
These ground-breaking findings from Oxford University looked at 168 elderly people experiencing levels of mental decline known as mild cognitive impairment.
This condition, marked by mild memory lapses and language problems, is beyond what can be explained by normal aging and can be a precursor to Alzheimer's and other forms of dementia.
Half of the volunteers were given a daily tablet containing levels of the B vitamins folate, B6 and B12 well above the recommended daily amount. The other half were given a placebo.
The pill contained 0.8mg of folic acid, 0.5mg of B12 and 20mg of B6.
After two years, the rate at which their brains had shrunk was measured.
The average brain shrinks at a rate of 0.5% a year after the age of 60. The brains of those with mild cognitive impairment shrink twice as fast. Alzheimer's patients have brain shrinkage of 2.5% a year.
The team found that on average, in those taking vitamin supplements, brain shrinkage slowed by 30%.
In some cases it slowed by more than 50%, making their brain atrophy no worse than that of people without cognitive impairment.
Vitamin B and Memory
Certain B vitamins - folic acid, vitamin B6 and B12 - control levels of a substance known as homocysteine in the blood. High levels of homocysteine are associated with faster brain shrinkage and Alzheimer's disease.
The study authors believe it was the B vitamins' effect on levels of homocysteine that helped slow the rate of brain shrinkage:
"These vitamins are doing something to the brain structure - they're protecting it, and that's very important because we need to protect the brain to prevent Alzheimer's."
High levels of homocysteine are also a very good marker of a poor lifestyle or disease, so things like a high sugar, refined diet, lack of exercise, etc, can push also homocysteine levels up.
Sources of Vitamin B
B vitamins are found naturally in many foods: vitamin B12 sources include meat, fish and eggs; folic acid and B6 are found in asparagus, lentils, most beans, and leafy green vegetables.
A healthy diet should ensure adequate intakes of the other B vitamins, but vitamin B12 can be tricky in the elderly because it is not absorbed as efficiently. This is because the older you get the more your digestive system breaks down. Specifically the lining of the stomach gradually loses its ability to produce hydrochloric acid, which is responsible for releasing vitamin B12 from food.
Vegetarians who don't eat fish or milk are also more likely to become deficient in this vitamin, as there is no known plant foods considered to be reliable sources of vitamin B12. Therefore additional supplementation may be required for these two groups.
Research Paper Details:
Smith AD, Smith SM, de Jager CA, Whitbread P, Johnston C, et al. (2010) Homocysteine-Lowering by B vitamins Slows the Rate of Accelerated brain Atrophy in Mild Cognitive Impairment: A Randomized Controlled Trial. PLoS ONE 5(9): e12244.