Scientific Report Enhanced cognitive performance after magnesium defecation: A randomized, double-blind, placebo-controlled, crossover study

Cognitive performance was measured under non-defecated, non-magnesium defecated, and magnesium defecated conditions among thirteen elite triathletes in a counter-balanced order. Real-time hemodynamic changes in the prefrontal brain and sub-navel regions proximal to rectum were also measured using near-infrared spectroscopy (NIRS), where both detected regions exhibited high glucose uptake under 18F-fluorodeoxyglucose positron emission tomography (PET) scans. We have found a significant shortened time to completion for the Stroop’s test under defecated conditions compared with the non-defecated condition (non-defecation: 27.1 ± 1.1 s; non-magnesium defecation: 24.4 ± 0.9 s, magnesium defecation: 23.4 ± 0.8 s each session, p < 0.05). Stroop’s performance improved after non-magnesium defecation among for nine of thirteen participants. Additionally, all participants performed better following magnesium defecation without exception, suggesting an additional role of magnesium on mental judgement. We have surprisingly found an increased oxygen consumption in the high glucose uptake sub-navel region in both defecated conditions during the test, evidenced by a decreased oxygenation (p < 0.05) with negligibly increased blood distribution. Prefrontal brain showed a minimal hemodynamic response under both defecated conditions. This study provides the first evidence which demonstrates an intriguing role of rectum distention in cognitive performance.