Vitamin B Supplements show no obvious benefit to brain health
Monday, September 30th, 2019
The B vitamins are often linked to brain health. They help to break down an amino acid in our blood called homocysteine, which contributes to cell ageing and to the build-up of amyloid and tau proteins in the brain associated with greater dementia risk. We know a rare condition called pernicious anaemia caused by low B12 levels can mimic dementia symptoms and be reversed with B12 injections; and Korsakoff Syndrome is a type of dementia caused by a deficiency in B1 (or thiamine) as a result of prolonged alcohol consumption. Researchers have long wondered whether taking vitamin B supplements benefit overall cognitive functioning.
Cause Vs Consequence
Earlier this year, researchers in Western Australia conducted a large review of 31 carefully controlled trials that compared B6, B12, or folate (B9) supplementation with placebo, amassing data from over 17,000 older adults with and without cognitive impairment[1]. The study found that lowering homocysteine using B vitamins did not improve cognitive performance or slow cognitive decline, as compared to placebo. This highlights the common issue of causality in dementia research. Do raised homocysteine levels cause cognitive decline, or rather are they a consequence of cognitive decline that triggers unhealthier lifestyle choices and vitamin deficiencies, for example?
Still, the authors caution that only ten of the 31 trials involved participants with existing cognitive impairment, and it makes sense that trials with healthy volunteers are less likely to show benefits of supplementation. Furthermore, the review only selected studies that used the Mini-Mental State Exam, a relatively simple, ten-minute measure of cognitive function, which may not pick up all types of cognitive impairment or more subtle changes over time.
Thinking Carefully About our Supplement Use
A third of Australians spend millions on dietary supplements each year[2]. At minimum, these findings do well to encourage us to consider our supplement use more thoughtfully. Sometimes it can be easy to take a pill, but we know that current research points more to lasting lifestyle changes, such as exercise and a Mediterranean diet, as being effective in reducing dementia risk.
[1] https://www.ncbi.nlm.nih.gov/pubmed/30949983
[2] https://www.abs.gov.au/ausstats/abs@.nsf/Lookup/by%20Subject/4364.0.55.007%7E2011-12%7EMain%20Features%7ESupplements%7E400
