A potential link between eating Marmite and activity in the brain has been identified by researchers, through the apparent increase of a chemical messenger associated with healthy brain function. Participants consuming a teaspoon of Marmite every day for a month, compared to a control group who consumed peanut butter, showed a substantial reduction of around 30 per cent in their brain’s response to visual stimuli, measured by recording electrical activity using electroencephalography (EEG).