The World Health Organization (WHO) estimates that over 55 million people have dementia worldwide, with Alzheimer’s disease accounting for 60-70% of cases. According to its estimates, with an ageing population, this figure is set to rise exponentially in the coming years, reaching 152 million people by 2050.

This public health problem has a cost – estimated to be more than US$818 billion annually in 2017 – and which could more than double by 2030. This gives researchers all the more reason to focus on finding sustainable solutions for preserving the cognitive functions of older people.

This is the aim of the Cocoa Supplement and Multivitamin Outcomes Study (Cosmos), a large-scale study conducted in the United States involving 21,442 participants aged 60 and over. It sets out to determine the impact of different types of dietary supplements on cardiovascular health, cancer, and other diseases.

For this latest instalment, researchers at Mass General Brigham, affiliated with Harvard University, focused specifically on the effectiveness or otherwise of taking one multivitamin supplement per day, compared with a placebo, on memory and overall cognition.

They followed 573 participants for two years, and also evaluated the results of a combined analysis of three different studies.

Published in the American Journal of Clinical Nutrition, the research was conducted in two phases: the first showed “a modest benefit” for daily multivitamin intake, compared with the placebo, on global cognition over the two years of follow-up, but “a statistically significant benefit” on episodic memory.

But it was the meta-analysis that highlighted “strong evidence of benefits for both global cognition and episodic memory”. All this led the researchers to suggest that taking a multivitamin every day can be effective in slowing overall cognitive ageing by the equivalent of around two years, again compared with taking a placebo.

“The findings provide strong and consistent evidence that taking a daily multivitamin, containing more than 20 essential micronutrients, helps prevent memory loss and slow down cognitive ageing,” first author Chirag Vyas explained.

Senior author Olivia Okereke concluded: “These findings will garner attention among many older adults who are, understandably, very interested in ways to preserve brain health, as they provide evidence for the role of a daily multivitamin in supporting better cognitive ageing.”

A previous Cosmos study looked at the benefits of cocoa flavanols on cognitive function. Researchers then reported that taking a daily supplement of cocoa extracts had no benefit on cognitive function, except in people with a poor-quality diet.