This piece is going to start (unusually for this writer) with a little humble pie. A few weeks ago I wrote about the widespread use of multivitamin supplements in otherwise healthy people, a $4 billion industry, and concluded that in all probability this resulted in very minimal benefit and expansive urine! Well, to paraphrase Hamlet I have been hoist on my own petard following the publication this month of the COSMOS-Mind study.

This was a large scale randomised clinical trial which tested whether daily administration of cocoa extract (containing 500 mg/day flavanols) versus placebo and a commercial multivitamin-mineral (MVM) versus placebo improved cognition in older women and men. The primary outcome was a global cognition composite of a variety of cognitive tests. Primary endpoint for both treatments was changes in the composite score at three years.

The results were surprising given that examining the effects of cocoa flavonoids was the primary aim of the study - The analysis clearly showed that cocoa extract did not benefit cognition. However, COSMOS-Mind provided the first evidence from a large, long-term, clinical trial to support the potential efficacy of a multivitamin and mineral supplement in improving cognition in older adults. The difference between the multivitamin and placebo was statistically significant. This difference was even more marked in trial subjects with a history of cardiovascular disease on entry.

This study clearly demonstrates the importance of large-scale studies over a longer timescale. Many investigators have looked at theobromine, the principal alkaloid of cacao beans, in a variety of indications including hypertension, chronic cough and as a mild stimulant that might improve cognition. Several of these early studies, usually on a small scale, seemed to indicate potential benefit in cognition, but tended to be used as evidence that natural supplements had far reaching health benefits. However, the COSMOS-Mind study, looking at over 2,000 subjects over three years could not identify any benefit. Yet, the effect of the multivitamin supplementation clearly did.

There are several interesting conclusions from this: often open studies can mislead us and that properly designed and conducted studies such as COSMOS-Mind are of great benefit in this disease area.

So, what will I do now? I will have to revise my views on the use of multivitamin supplementation in older patients and to accept that this might well have significant benefits in those without any overt deficiency. Finally, I’ll help myself to a slice of humble pie, although I might pass on the chocolate sauce!

The full COSMOS-Mind study is available as an e-publication:
Effects of cocoa extract and a multivitamin on cognitive function: A randomized clinical trial