Chocolate could help age-related memory decline in those with a low quality diet

30 Apr 2024

Find out more about StepUp for Research’s work into ageing and dementia on their website,

StepUp for Ageing Research April 2024

For years we have debated whether dark chocolate is good for our brain health[1]. The Cocoa Supplement and Multivitamin Outcomes Study (COSMOS) set out to try to answer this once and for all[2]

In a sample of 3,562 predominantly white, highly educated older adults, half were randomly assigned a daily dose of 500mg of cocoa flavanol – the ingredient in chocolate tagged for being responsible for any cognitive benefits – whilst the other half were assigned a placebo[3]. All participants completed assessments of hippocampal-dependent memory – an area of the brain thought to be particularly sensitive to ageing.  A subset of 1,361 participants provided data on habitual diet quality and a urine-based biomarker of flavanol consumption.

Flavanol consumption as the potential dietary driver of cognitive ageing

Whilst there were no intervention-related improvements in memory after one year, the study found that people with low baseline levels of flavanols, “restored” their age-related mental decline to levels similar to people who had healthy flavanol levels at baseline, akin to a depletion–repletion paradigm. For those individuals who already reported a good quality diet, there were no significant improvements in cognitive function. The effect size of the flavanol associated increase in memory was small.  However, this is common in diet or lifestyle modification studies, and the authors argue that it is still enough to be meaningful to health maintenance. The finding also needs to be replicated in a more diverse sample if we are to generalise it to the broader population.

In summary, eating several squares of dark chocolate a day could be beneficial for brain health, but only if your flavanol levels are already low. There may be little benefit in eyeing up more squares than the recommended 500mg. Even then, there are healthier ways to achieve 500mg of flavanol, such as apples, berries, kale and tea.

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