In response to the study, partly funded by Mars, Dr Susan Kohlhaas, Director of Research at Alzheimer’s Research UK, emphasises the supplement's use over chocolate as a main flavanol source.
“The study used cocoa flavanol supplements provided to participants in capsule form,” says Dr Kohlhaas.
“While cocoa beans are the basis for chocolate, chocolates are not a reliable source of flavanol compounds, and this study does not suggest that eating chocolate is good for our cognitive health.
“This study didn’t look at dementia, and we can’t know from this research whether a diet high in cocoa would have any effect in either preventing or delaying the onset of the condition.”
Findings made by the Columbia University team suggested those on a high-flavanol diet performed better in a list-learning task compared to the placebo group.
However, the group did did not find a relationship between flavanol intake and performance on two other cognitive tests one of which was the primary endpoint for the study.
In addition, there was no effect of 12 weeks of flavanol supplementation on blood flow to the region of the brain the researchers had identified in advance of the study.
Benton Visual Retention Task
The research team acknowledged this as a principal study limitation, saying its inclusion was to overcome the limitation of its predecessor, the Benton Visual Retention Task, that tested patients with profound cognitive impairments.
“The newly developed task was designed to be more challenging so as to ‘stress’ the Dentate Gyrus (DG), (a region within the hippocampal circuit vulnerable to aging) among healthy elders.
“Our finding, showing that most participants performed no better than chance, suggests that it might be too challenging, compromising our ability to adequately test the primary hypothesis.”
“This small trial highlights some possible effect of flavanols found in cocoa beans over a short time period,” adds Dr Kohlhaas.
“We’d need to see much longer, large-scale studies to fully understand whether a diet high in these flavanols could boost cognition in old age,”
“We also don’t know how meaningful the improvements measured in the tests used here would be for people in their daily lives.”
In the discussion, the team also considered the presence of caffeine in their test materials arguing that it did not affect the findings of the study.
While caffeine’s effects on alertness, mood and concentration are known, sustained effects at intakes at or below 25 milligrams per day (mg/day) on cognitive performance are unproven in epidemiological or intervention studies.
“We were interested in the longer-term, and not the acute effects of flavanols on memory and cognitive function,” the team states.
“Our study was designed to undertake all cognitive performance tests at least 12 hours after flavanol intake, thus excluding the potential transient impact of caffeine on vasomotor function as well as on the other endpoints investigated.
“This is further supported by measurements of caffeine in plasma collected at each study visit, which did not identify significant differences in the levels of caffeine after test material intake.”
Further studies needed
The researchers concluded that the study raised the possibility that at the population level, flavanol-based dietary interventions may have a beneficial impact on cognitive aging.
“Dietary flavanols may offer meaningful benefits to cognitive health, although further studies are needed,” they write.
“Replication of our findings at scale, potentially through ongoing studies like COSMOS, may allow for an evidence-based assessment at the population level of the utility of dietary flavanols to address the significant challenge of age-related cognitive decline in late life.”
Source: Scientific Reports
Published online: DOI: 10.1038/s41598-021-83370-2
“Insights into the role of diet and dietary favanols in cognitive aging: results of a randomized controlled trial.”
Authors: Richard Sloan