Insights into the role of diet and dietary flavanols in cognitive aging: results of a randomized controlled trial.
Study Goal
The researchers aimed to determine whether cocoa flavanols could improve memory function in healthy aging adults, particularly targeting hippocampal-dependent cognitive tasks.
Results Summary
Flavanols improved hippocampal-dependent list-learning performance, especially in participants with poorer baseline diet quality, but did not affect object-recognition or list-sorting tasks. Imaging suggested flavanols may target the dentate gyrus.
Population
211 healthy adults aged 50-75 years.
Effective Dosage
260, 510, and 770 mg/day.
Duration
12-week intervention followed by 8-week washout.
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
cocoa flavanols (260, 510 and 770 mg/day) | no change | object-recognition performance | 211 healthy adults (50-75 years) | - | did not improve | #1 |
cocoa flavanols (260, 510 and 770 mg/day) | no change | list-sorting performance | 211 healthy adults (50-75 years) | - | did not improve | #2 |
cocoa flavanols (260, 510 and 770 mg/day) | increase | hippocampal-dependent list-learning performance | 211 healthy adults (50-75 years) | - | improved | #3 |
cocoa flavanols (260, 510 and 770 mg/day) | increase | hippocampal-dependent list-learning performance | participants in the bottom tertile of baseline diet quality | - | improved | #4 |
dietary flavanols | neutral | dentate gyrus | MRI substudy participants | - | target | #5 |
baseline diet quality | neutral | hippocampal-dependent list-learning performance | 211 healthy adults (50-75 years) | - | directly associated with | #6 |
baseline diet quality | no change | object-recognition performance | 211 healthy adults (50-75 years) | - | did not correlate with | #7 |
baseline diet quality | no change | list-sorting performance | 211 healthy adults (50-75 years) | - | did not correlate with | #8 |
With the world's population aging, age-related memory decline is an impending cognitive epidemic. Assessing the impact of diet on cognitive aging, we conducted a controlled, randomized, parallel-arm dietary intervention with 211 healthy adults (50-75 years) investigating effects of either a placebo or 260, 510 and 770 mg/day of cocoa flavanols for 12-weeks followed by 8-weeks washout. The primary outcome was a newly-developed object-recognition task localized to the hippocampus' dentate gyrus. Secondary outcomes included a hippocampal-dependent list-learning task and a prefrontal cortex-dependent list-sorting task. The alternative Healthy Eating Index and a biomarker of flavanol intake (gVLM) were measured. In an MRI substudy, hippocampal cerebral blood volume was mapped. Object-recognition and list-sorting performance did not correlate with baseline diet quality and did not improve after flavanol intake. However, the hippocampal-dependent list-learning performance was directly associated with baseline diet quality and improved after flavanol intake, particularly in participants in the bottom tertile of baseline diet quality. In the imaging substudy, a region-of-interest analysis was negative but a voxel-based-analysis suggested that dietary flavanols target the dentate gyrus. While replication is needed, these findings suggest that diet in general, and dietary flavanols in particular, may be associated with memory function of the aging hippocampus and normal cognitive decline.