Vitamin B12 and Brain Health

Earlier research has shown that patients with Alzheimer's have much lower B12 levels than healthy people. Vitamin B12 level in brain tissue (spinal fluid) is also very low in those with chronic fatigue syndrome — despite normal blood levels!

In this study, it was found that people with lower B12 levels, despite the vitamin B12 levels still being well within the normal range, had decreased function in the "white matter" of the brain. It is suspected that this was caused by problems with myelin, which is the protective coating around nerves that also helps transmit nerve signals. This coating is also damaged in people with multiple sclerosis.

This is one more study suggesting that our so-called "normal ranges" for many blood tests has nothing to do with health and that we should use normal ranges based on what will help your body to function optimally. For more information on this see The problem with lab testing.

Although the RDA (the Recommended Dietary Allowance — Which I Call the Ridiculous Dietary Allowance) for Vitamin B12 is 2.4 mcg daily, I recommend that people get at least 500 mcg daily. This is the amount found in a good multivitamin powder. High levels of vitamin B12 are also found in many herbal supplements that promote mental alertness, which can help support brain health.

Plasma Vitamin B12 Status and Cerebral White-Matter Lesions

Background and Objective

Elevated homocysteine has been associated with a higher prevalence of cerebral white-matter lesions and infarcts, and worse cognitive performance. This raises the question whether factors involved in homocysteine metabolism, such as vitamin B12, are also related to these outcomes. This study examined the association of several markers of vitamin B12 status with cerebral white-matter lesions, infarcts, and cognition.

Methods

The study evaluated the association of plasma concentrations of vitamin B12, methylmalonic acid, holotranscobalamin, and transcobalamin saturation with cerebral white-matter lesions and infarcts at baseline and cognition at baseline and during follow-up among 1,019 non-demented elderly participants of the population-based Rotterdam Scan Study. Analyses were adjusted for several potential confounders, including homocysteine and folate concentration.

Results

Poorer vitamin B12 status was significantly associated with greater severity of white-matter lesions, in particular periventricular white-matter lesions, in a concentration-related manner. Adjustment for common vascular risk factors (including blood pressure, smoking, diabetes, and intima media thickness) did not alter the associations. Adjustment for homocysteine and folate modestly weakened the associations. No association was observed for any of the studied markers of vitamin B12 status with presence of brain infarcts and baseline cognition or cognitive decline during follow-up.

Conclusions

These results indicate that vitamin B12 status in the normal range is associated with severity of white-matter lesions, especially periventricular lesions. Given the absence of an association with cerebral infarcts, it is hypothesized that this association is explained by effects on myelin integrity in the brain rather than through vascular mechanisms.

Reference:

Published Online First: 31 October 2008. doi:10.1136/jnnp.2008.149286. Journal of Neurology, Neurosurgery, and Psychiatry 2009;80:149-157

L M L de Lau, A D Smith, H Refsum, C Johnston, M M B Breteler

Department of Epidemiology & Biostatistics, Erasmus Medical Centre, Rotterdam, The Netherlands