Chocolate and supplement research makes strange partnerships, but hints at a little brain boosting

Scientific researchers find funding in strange places, but support for clinical trials from Mars, a company best known for candy bars, has to be among the strangest. Pair it with support from the maker of a well-known brand of multivitamin, and you’ve got the COcoa Supplement and Multivitamin Outcomes Study, or COSMOS, intended to test the health effects of the seemingly disparate combination of cocoa extract and a multivitamin for seniors.

Touted as an “important partnership across academic, industry and government collaborators,” COSMOS is sited at two major academic research centers, the Harvard-affiliated Brigham and Women’s Hospital and the Fred Hutchinson Cancer Research Center in Seattle. Between them, groups at these institutions have assessed the value of cocoa extract (the Mars association) and Centrum Silver (the multivitamin association) separately and together in offering benefits against cancer and cardiovascular disease events and the effects of age on the brain.

Unfortunately for the chocolate aficionados out there (e.g., me), the cocoa extract studies have shown no effect on overall cardiovascular events and only a possible dent in some outcomes among those who stuck religiously to taking the supplements. Findings came up dry in terms of brain-boosting benefits, leaving us simply to continue enjoying chocolate for its own sake.

The branded multivitamin results have been more mixed. The supplement was not linked to increased risk for some cancers or for cardiovascular disease, which has been a concern, but benefits on these fronts were elusive.

Results for the brain are more promising. One set of findings from the COSMOS studies showed that for people in their 60s or older, taking the multivitamin was associated with better verbal recall at three years compared with those taking a placebo. The authors estimated that the benefit was equal to preventing just over three years’ worth of age-related memory loss.

The researchers assessed several kinds of memory capacities in the 3,562 study participants, including immediate recall of words, recall of words after a delay (memory retention), attention and recognition of new objects. The results showed an effect over placebo only for immediate recall.

These findings are different from an earlier COSMOS study analyzing the effects of the multivitamin on memory components combined and separately. In that more preliminary analysis, attention, overall cognition and memory all improved among those taking the supplement.

In turn, these jumbled findings about multivitamins and cognitive improvements are at variance from another large study addressing the question, published a decade ago. In the Physicians’ Health Study II, participants were all men and all doctors, age 65 or older. The results showed no benefit of a multivitamin (also Centrum Silver) on overall cognition.

These studies have some important limitations. For some of the COSMOS trials, participants had to have online access and their own computer, and almost all were White with at least some college. Obviously, participants in the Physician’s Health Study were all well educated. Together, they represent a selected group that might not generalize across the population. The studies also used a specific formulation of multivitamin, provided by the company that makes it, so the effects of different formulations aren’t known.

It’s also worth noting a certain pattern in these studies and others related to brain and the rest of the body. The worse the baseline condition, the bigger improvements can be. Well-fed, well-educated, well-interneted study participants without malnutrition may have little room for improvement in brain or other health, whereas people with existing health problems or lower baseline memory scores, for example, might show more gains. There are hints of these patterns in the COCOA findings, with people who have existing heart disease, for example, possibly experiencing greater brain improvements with the multivitamin.

Finally, in one more separate COSMOS analysis, researchers found a link between better memory and increasing intake of dietary flavanols, compounds present in chocolate and other plant-based foods that are predicted to offer brain benefits. They reported improvements specifically in people who had low flavanol intake at baseline.

The advice for the aging brain and body likely has changed little since any of us were little: eat your fruits and vegetables (and maybe chocolate?), and supplements may be superfluous.

Emily Willingham is a Marin science journalist, book author and biologist. You can find her on Bluesky @ejwillingham or Instagram at emily.willingham.phd.