The Role of Short Chain Fatty Acids in Microbiota-gut-brain Axis

The study is an interventional double‐blind, placebo‐controlled, parallel group design with 3 arms (placebo, high‐dose of SCFA, and low‐dose of SCFA). The high and low doses of SCFA are equivalent to 20 and 10 grams of fiber respectively. Healthy male participants follow a low‐fiber diet for the study duration (11 days). On day 4, baseline measurements are taken in the lab, including biological samples and psychophysiological measurements. Participants then consume placebo or SCFA for one week and revisit the lab on day 11 for a second measurement of the outcomes of interest. Specifically, we investigate the effect of SCFA supplementation on affective processing, including stress sensitivity, fear‐related processes (e.g. extinction learning), and attentional bias to emotional stimuli. Volunteers also respond to questionnaires in relation to mood, and provide biological samples (blood and faecal samples) for analysis of circulating short chain fatty acids and microbiota composition, respectively.