The Gut Check · Episode 8

A Probiotic That Eased Constipation — and Mood

A 2026 randomized trial of one strain improved regularity, raised butyrate, and lifted psychological well-being together — the gut-brain axis in a single study.

Hosted by Robin Vale · with Craig Rouskey, MSc · ~5 min

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The paper (every claim, linked)

  1. Wu et al. (2026). Weizmannia coagulans BC99 improved intestinal motility and chronic constipation through regulating gut microbiota: a randomized, double-blind, placebo-controlled trial. European Journal of Nutrition. PMID 41886091
  2. Dalile B, Van Oudenhove L, Vervliet B, Verbeke K (2019). The role of short-chain fatty acids in microbiota-gut-brain communication. Nature Reviews Gastroenterology & Hepatology. PMID 31123355

Full transcript

Robin Vale: A 2026 trial set out to test a probiotic for constipation and found something extra. Craig?

Craig Rouskey, MSc: Right — Wu and colleagues, in the European Journal of Nutrition, ran an eight-week randomized, double-blind, placebo-controlled trial of a strain called Weizmannia coagulans BC99 in constipated adults.

Robin Vale: Did it work for the constipation?

Craig Rouskey, MSc: Yes — it significantly improved bowel-movement frequency and stool consistency, and it cut colonic transit time. But the part that makes this a gut-brain story is what came alongside it.

Robin Vale: Which was?

Craig Rouskey, MSc: Psychological well-being improved too — measured on the Depression, Anxiety and Stress Scale. And mechanistically it shifted the microbiome toward Lactobacillus and Bifidobacterium and away from Escherichia-Shigella, and it raised fecal short-chain fatty acids, including butyric acid.

Robin Vale: So the gut and the mood moved together.

Craig Rouskey, MSc: That's the gut-brain axis in one trial — feed the ecosystem, the short-chain fatty acids rise, regularity improves, and mood tracks along. It's one strain in one study, so I won't oversell it. But it's a clean example of why 'just a gut thing' and 'just a mood thing' are usually the same thing.

Robin Vale: Craig, thank you. The trial's in the notes. This has been The Gut Check.

The Gut Check is produced with AI-assisted voices — the host is a presenter voice and Craig Rouskey, MSc is a real microbiome scientist whose interpretation this is. Every study cited is real and linked to PubMed. Educational only — not medical advice.