A randomised controlled study to investigate the cognitive, mood, metabolic and anti-inflammatory effects of acute oyster mushroom intervention in healthy older adults

The Pleurotus oyster is a common edible mushroom rich in ergothioneine, a bioactive that has shown benefits to cognition in animals when administered in extract form. The OYSACO study investigated the acute effects of oyster mushroom (OM) on cognition, mood, inflammation and metabolism in healthy older adults. In a cross-over study, 33 participants consumed a noodle soup containing 0.5 (OM0.5), 1 (OM1) and 2 (OM2) servings of OM, and a calorie-matched control soup (OM0), on four separate occasions, each separated by one week. Cognitive function, mood and subjective appetite were assessed at baseline (BL, prior to intervention) and then at 2-, 4- and 6-hours post-consumption. Intervention palatability was recorded after consumption, and a serum sample was taken at 6-hours. Linear Mixed Modelling, with BL as covariate, revealed a significant decline in Positive Affect and concomitant increase in Mental Fatigue over the test day after consuming OM0, while no significant variation in mood was seen throughout the day following OM interventions. Cognitive findings were mixed with no consistent pattern of effects seen following OM interventions compared to OM0. Postprandial inflammatory markers (nitrite, NADPH oxidase 2 and inducible nitric oxide synthase) were significantly lower following OM interventions compared to OM0. Unexpectedly, brain derived neurotrophic factor was found to be dose-dependently lower after consuming OM compared to OM0. Overall, OM interventions helped maintain mood and lower inflammatory markers in healthy older adults, following acute supplementation. Further studies are required to unravel the underlying mechanisms involved.