The study found that supplementation had the most pronounced effect on subjects with poor quality diet at baseline.
A recent ancillary study of the COcoa Supplement and Multivitamin Outcomes Study (COSMOS), called COSMOS-Web1, investigated the effects of flavanol supplementation on memory. The cohort included 3,960 subjects, 3,563 of which completed at least one yearly follow-up, who were randomized to receive a flavanol-containing cocoa extract or placebo daily for three years. Researchers used web-based cognitive assessments to measure changes in cognitive function. Specifically, ModRey was used to measure hippocampal memory, which was the primary outcome. Color/Directional Flanker Task was used to measure prefrontal cortex function, and ModBent measured dentate gyrus function.
The primary analysis showed no differences between the treatments for the primary and both secondary outcomes. However, the researchers hypothesized that the impact of flavanol supplementation for ModRey may be more pronounced in subjects with a poorer baseline diet quality. The researchers therefore stratified the participants into tertiles based on the distribution of baseline aHEI scores. The researchers explain that a “low aHEI score reflects a a diet quality ranging from the US average to slightly below average; the medium aHEI tertile ranges from average to well-above average; and the high aHEI tertile includes people with a substantially better diet than that of the average American.”
The lowest tertile had the poorest memory performance at baseline based on the hippocampus-mediated ModRey test, and ModRey was improved following flavanol consumption in the low aHEI tertile, but not the medium and high tertiles. To test whether hippocampal-dependant memory was correlated with habitual flavanol consumption, the researchers measured a urine-based biomarker of flavanol consumption (gVLM) and stratified these measurements into tertiles (low, medium, and high). The researchers were then able to confirm their hypothesis that the effects of flavanol on ModRey were statistically different across gVLM tertiles, with significant improvements from flavanol supplementation in the lowest gVLM tertile.
“We are not only living longer, but we are living cognitively more demanding lives,” write the researchers. “Our findings suggest that flavanol consumption might be considered in future dietary recommendations, perhaps together with the flavanol biomarker, specifically geared toward preventing or improving brain health in later life.”