Bifidobacterium longum and mood

What 4 graded rows on bifidobacterium longum agree on for mood, and where they differ. Counted side by side, never averaged.

Consensus finder Rows from the Bifidobacterium longum page, reviewed Oct 21, 2026 How it decides

What the rows agree on

Each block and row is one graded row from the Bifidobacterium longum page, with its PubMed record.

Your question

Mood4 IBS2

Supplement

Bifidobacterium longum Choose another

Bifidobacterium longum and mood

4 rows · 436 people

Split. 1 row found an improvement, 1 found no difference and 2 had mixed results.

No difference or mixed

Improved

Each block is one evidence row, sized by how many people it enrolled, with its grade inside. Outlined: mixed results.

Grade C× 2
Grade D× 1
No effect× 1

Rows: 4
Trials: 4
People: 436

Where they differ

From the rows

Trial sizeHow longWho was studiedWhen published

The best-graded row, grade C, is a randomized trial of 168 people (2026) and reported mixed results. 1 row is graded No effect, our grade for adequately powered trials that found no effect.

The row that found no difference was larger: 184 people, against 44 people for the row that found an improvement.

The row that found no difference ran longer (7 months) than the row that found an improvement (6 weeks).

Only the row that found no difference names women in its population.

The row that found no difference is newer (2025) than the row that found an improvement (2017).

2 rows with mixed results are left out of this comparison.

The rows

1 improved · 1 no difference · 2 mixed

Grade CDepression scores in IBS with anxiety or depression · Improved
Pilot RCT · n 44 · 2017 · Adults with IBS (diarrhoea or mixed) and mild to moderate anxiety or depression (McMaster University)
Daily (CFU not stated in the abstract) · 6 weeks
14 of 22 on the probiotic vs 7 of 22 on placebo had depression scores fall by 2 or more points (P = .04); quality of life rose. No effect on anxiety or IBS symptoms.
Row on the Bifidobacterium longum page · PubMed 28483500 (opens PubMed)
No effectAnxiety and depressive symptoms in pregnancy and after birth · No difference
RCT · n 184 · 2025 · Pregnant women followed to 12 weeks after delivery (three arms)
Daily (CFU not stated in the abstract) · From about 30 weeks of pregnancy, or from birth, until 12 weeks after delivery
No differences between groups in depressive (EPDS) or anxiety (STAI) scores; the strain was not detected in all participants after the intervention.
Row on the Bifidobacterium longum page · PubMed 40175540 (opens PubMed)
Grade CDepressive symptoms in mild to moderate depression · Mixed
RCT · n 168 · 2026 · Adults aged 18 to 70 with mild to moderate depression
10 billion CFU/day · 8 weeks
The primary outcome, Beck Depression Inventory-II change, did not differ from placebo at week 4 (P = .718) or week 8 (P = .132). Sleep quality and PHQ-9 improved more at week 4 only; vitality stayed better at week 8 (P = .042).
Row on the Bifidobacterium longum page · PubMed 42060410 (opens PubMed)
Grade DBrain activity and vitality under social stress · Mixed
RCT · n 40 · 2019 · Healthy volunteers (Tubingen, Germany)
1 billion CFU/day · 4 weeks
1714 altered resting brain oscillations, which tracked with vitality changes, and altered responses during a social-stress game; there was no effect on stress at the behavioural level, which the authors attribute to small numbers.
Row on the Bifidobacterium longum page · PubMed 30998517 (opens PubMed)

Read onRead the full evidenceThe full evidence chapter on its page, with every outcome and its sources.