While some deterioration in cognitive function is normal with aging, the increasing life expectancy of the global population means that deferring and reducing such deterioration is more important than ever. In this double-blind, controlled, parallel-arm study, 90 elderly individuals aged 61-85 years who showed no evidence of cognitive impairment were randomly assigned to daily consumption of drinks containing different levels of cocoa flavanol, either high flavanol (HF; 993 mg), intermediate flavanol (IF; 520mg) or low flavanol (LF; 48 mg). The study was performed over an eight-week period. These drinks were nutritionally matched and specially prepared. The HF and IF cocoa drinks were produced using Mars' patented Cocoapro process, while the LF drink was made from highly processed, alkalized cocoa powder. Normal diets and regular lifestyle were maintained throughout the study period apart from the supplementation of the diet with the drinks. Cognitive function was assessed at the beginning and the end of the eight-week study period using three tests, namely the Mini-Mental State Examination (MMSE), the Trail Making Test (TMT) A and B, and the Verbal Fluency Test (VFT).
The results of the study showed no differences were observed between groups for the MMSE. However, for the TMT, the improvement in the mean time to complete tests A and B after consumption of the drinks was significantly greater in the HF and IF groups compared to the LF group. For the VFT, performance improved in all three groups, however the magnitude of the improvement was significantly greater in the HF compared to either the IF or the LF groups. Beyond the improvements in cognitive function, the results of the study also indicated significant improvement in cardiometabolic outcomes, including insulin resistance, blood pressure and lipid peroxidation.
The mechanism behind the improvement in cognitive function in response to cocoa flavanols is not fully understood but the study's authors suggest that the improvements in insulin resistance and blood pressure may be significant in this regard. Lead author Dr. Giovambattista Desideri explains: "Earlier studies suggest a central role for insulin resistance in brain aging…These results could therefore provide some insight into a possible mechanism of action for the cognitive improvements we have observed." Improvements in vascular function as a result of cocoa flavanol consumption are indicated in various studies over the past decade. Co-author Dr. Catherine Kwik-Uribe, human health and nutrition director at Mars, Incorporated, says, "Since the brain is a heavily vascularized tissue, we might also be looking at vascular improvements as underlying the observed improvements in cognitive function."
While these results on cocoa flavanols are encouraging, there is a note of caution to be sounded to those who might be reaching for the chocolate. The trial was carried out with a special cocoa flavanol test product, which is designed to deliver a standardized amount of flavanols within a nutritionally suitable drink. Unfortunately, commercially available chocolate has a variable flavanol content and, given its macronutrient profile, is not recommended as a health food.
Mastroiacovo D et al. Cocoa flavanol consumption improves cognitive function, blood pressure control, and metabolic profile in elderly subjects: the Cocoa, Cognition, and Aging (CoCoA) Study—a randomized controlled trial. Am J Clin Nutr doi: 10.3945/ajcn.114.092189
Desideri G et al. Benefits in Cognitive Function, Blood Pressure, and Insulin Resistance Through Cocoa Flavanol Consumption in Elderly Subjects With Mild Cognitive Impairment: The Cocoa, Cognition, and Aging (CoCoA) Study. Hypertension 60: 794-801; doi:10.1161/HYPERTENSIONAHA.112.193060
Press release: Mars Symbioscience; available at http://www.eurekalert.org/pub_releases/2015-01/ms-med010615.php