Supplement analysis backed by scientific evidence · PT

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Limited evidenceGeneral health

Brewer's Yeast

A cheap, genuine source of B vitamins, protein, beta-glucan and chromium. The best-studied claim — improved glucose tolerance in type 2 diabetes — comes from small older trials with mixed results, and it is a bitter food ingredient rather than a targeted supplement.

What the science says

  • Improves glucose tolerance and lipids in type 2 diabetes Limited evidence

    A controlled trial in adults with type 2 diabetes compared chromium-rich brewer's yeast (roughly 23 mcg chromium/day) with chromium chloride over 8 weeks and found improvements in glucose tolerance and lipid profile with the yeast arm, and some participants reduced medication. Similar older work in Chinese adults reported improved oral glucose tolerance on 9 g/day brewer's yeast. Sample sizes were small (dozens), the trials predate modern standards, and larger chromium trials have generally been negative — so treat this as suggestive at best.

  • Is a meaningful source of B vitamins and protein Moderate evidence

    Nutritionally this is solid: brewer's yeast is roughly 40-50% protein by weight and a dense source of thiamin, riboflavin, niacin, B6 and folate. Two tablespoons (about 15 g) can supply well over 100% of the RDA for several B vitamins. Note that debittered brewer's yeast retains the nutrients; unfortified yeast contains no reliable B12.

  • Yeast beta-glucan supports immunity Moderate evidence

    A systematic review and meta-analysis of yeast beta-glucan trials in healthy adults found reduced incidence and symptom burden of upper respiratory tract infections, typically at 250-500 mg/day of purified beta-glucan for 8-12 weeks. Brewer's yeast contains beta-glucan but is not standardized for it, so a whole-yeast product does not reliably deliver the studied dose.

  • Increases breast milk supply Limited evidence

    Brewer's yeast is a traditional galactagogue and a common ingredient in lactation cookies. There are no controlled trials showing it increases milk volume; the observed effect is more plausibly from the extra calories, fluid and B vitamins than from any specific yeast compound.

Dosage & safety

Studied doseTrials used roughly 9 g/day of brewer's yeast or standardized chromium-enriched yeast supplying about 20-25 mcg chromium/day, for 8-12 weeks. Common food use is 1-2 tablespoons (7.5-15 g) daily in smoothies or on food; tablets are typically 500-1000 mg, requiring many tablets to match a food dose. For immune beta-glucan effects, purified yeast beta-glucan at 250-500 mg/day is the studied preparation.
SafetyBloating, flatulence and gas are common at first, particularly from the beta-glucan and fibre. Contains tyramine and other amines — avoid with MAO inhibitor antidepressants, where it can precipitate hypertensive crisis. High in purines, so use caution with gout or hyperuricemia. Live or non-debittered brewer's yeast should be avoided in immunocompromised patients and those with central venous catheters, given rare reports of Saccharomyces fungemia. May worsen symptoms in people with yeast sensitivity or Crohn's disease (anti-Saccharomyces antibodies). Brewer's yeast from beer production may contain gluten residues; look for a gluten-free certification if coeliac. Can interact with diabetes medication by additively lowering glucose.

Scientific references

Where to buy

NOW Foods, Brewer's Yeast, 1 lb (454 g)

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