03/04/2026
https://www.facebook.com/share/p/1H1DE8AzJM/
A large international genetic study has identified vitamin B1 (thiamine) metabolism as a surprising factor influencing how often people have bowel movements. Published in Gut (January 2026), researchers analysed genetic data from 268,606 individuals of European and East Asian ancestry to investigate stool frequency, a commonly used proxy for gut motility. They identified 21 independent gene loci, including 10 novel signals implicating bile acid synthesis (KLB) and cholinergic signalling (COLQ). Fine-mapping pointed strongly toward two genes involved in thiamine transport and activation, SLC35F3 (a thiamine transporter) and XPR1 (phosphate exporter essential for thiamine activation).
This B1 connection was then reinforced by the scientistsβ analysis of observational data from nearly 100,000 UK Biobank participants. It showed that higher dietary (food-derived, supplemental intervention was not assessed) thiamine intake was associated with more frequent bowel movements, with the strength of this relationship significantly modified by an individualβs genetic profile. Specifically, the combined SLC35F3/XPR1 genotype score significantly modulated this effect (p