Human memory is notoriously fickle. It is prone to bias, hopelessly bound to emotional triggers, frequently just plain wrong, and we could all benefit from it being a bit more adequate all round.
Now, scientists say there is compelling evidence to suggest dark chocolate may be more than just a guilty pleasure, and could actually sharpen memory and boost our brain power.
Research in mice found that flavanols – bitter compounds abundant in dark chocolate, red wine and berries – appear to enhance cognitive function for around an hour after ingestion.
Mice given flavanols an hour before a memory challenge were about 30 per cent better at spotting new objects compared to a control group which had only been given water.
A research team at Japan’s Shibaura Institute of Technology said the sharp, bitter notes in cocoa can spark a well‑timed burst of noradrenaline in the hippocampus, the part of the brain that turns short‑term memories into long term ones.
Flavanols have already been associated with improved memory and cognition, as well as protection against neuronal damage.
The study, published in Current Research in Food Science, helps explain why previous, larger trials have reported memory boosts in human adults who regularly enjoy these compounds.
The flavanols appear to give the body’s stress‑response system a gentle nudge at just the right moment – like a kind of biochemical cue card for the brain, the team said.
The research initially focused on flavanols’ poor bioavailability – only a tiny fraction actually enters the bloodstream after ingestion. So the team sought to bridge this knowledge gap: how can flavanols influence brain function and the nervous system when so little of them are absorbed?
The study tested the hypothesis that the astringent taste of flavanols may in itself act as a direct signal to the brain.
Lead researcher, Dr Yasuyuki Fujii, said: “Flavanols exhibit an astringent taste. We hypothesised that this taste serves as a stimulus, transmitting signals directly to the central nervous system. As a result, it is thought that flavanol stimulation is transmitted via sensory nerves to activate the brain, subsequently inducing physiological responses in the periphery through the sympathetic nervous system.”
Behavioural tests revealed the flavanol-fed mice “exhibited greater motor activity, exploratory behavior, and improved learning and memory compared to controls,” the team said.
Dr Fuji added: “These results demonstrate that flavanol intake can trigger wide-ranging physiological responses resembling those induced by exercise – functioning as a moderate stressor that activates the central nervous system and enhances attention, arousal, and memory.
“Stress responses elicited by flavanols in this study are similar to those elicited by physical exercise. Thus, moderate intake of flavanols, despite their poor bioavailability, can improve the health and quality of life.”
