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Brewer's Yeast

Scientific Name(s): Saccharomyces cerevisiae
Common Name(s): Baker's yeast, Betafectin, Brewer's yeast, Dried yeast fermentate, EpiCor, Fibercel, Yeast
Drug class: Antidiarrheals, Probiotics

Medically reviewed by Last updated on Aug 23, 2021.

Clinical Overview


Brewer's yeast is traditionally used as a source of vitamin B, selenium, and chromium, especially by vegetarians. Clinical trials have evaluated yeast for a role in immunomodulation, respiratory infections, prevention of postsurgical infections (as beta-glucan), and as a source of dietary fiber to improve the lipid profile. However, quality trials are lacking.


Upper respiratory tract infections: S. cerevisiae 500 mg daily has been used in clinical trials over 12 weeks to treat respiratory infections and allergic rhinitis. Laxative: 6 to 50 g of fresh brewer's yeast over 3 days was used in a study for the treatment of cancer-related constipation. Acute diarrhea: 500 mg daily of brewer's yeast is recommended in the German Commission E Monographs.


Crohn disease; concomitant monoamine oxidase inhibitor (MAOI) therapy.


Information regarding safety and efficacy in pregnancy and lactation is lacking.


Brewer's yeast contains tyramine. Avoid concurrent use with MAOIs.

Adverse Reactions

Mild GI symptoms, including flatulence.


Information is limited. Brewer's yeast has Food and Drug Administration (FDA) GRAS (generally recognized as safe) status.


Brewer's yeast is most commonly produced from S. cerevisiae, a simple eukaryotic cell, but sometimes the related Saccharomyces exiguous or Saccharomyces boulardii are used. Many different strains of the yeast exist, and preparations may be produced from different sources. As a health supplement, the deactivated yeast is utilized and is available in powder, flake, tablet, and liquid forms. A yeast extract is also manufactured commercially by adding salt to a yeast suspension, causing autolysis of the protein content.Blumenthal 1998, Moyad 2007


Use of yeast in baking and brewing date to 2000 BC, with records found in Egyptian tombs. Traditionally, brewer's yeast has been used as a food supplement, especially as a source of B vitamins for vegetarians. It is also used as a protein supplement, energy booster, and immune enhancer, as well as in the treatment of diarrhea and acne.Blumenthal 1998, Lee 2009, Moyad 2007


S. cerevisiae serves as an abundant source of the B-complex vitamins, minerals, and proteins, while being notably low in fat and sodium. B vitamins include thiamine (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), folic acid (B9), and biotin (B7). However, brewer's yeast does not contain cyanocobalamin (B12) and would need to be obtained from other sources. Minerals provided by brewer's yeast include selenium, chromium (one of the richest natural sources of chromium), and zinc. Additionally, the cell wall of yeast provides a better source of beta-glucan fiber than oats.Bell 1999, Lee 2009, Shils 2006, Takahashi 2006

Uses and Pharmacology

Limited trials have been conducted on S. cerevisiae as a single ingredient preparation by a small pool of researchers. Studies have also focused on selenium- and chromium-enriched yeast preparations used in diabetes and cancer patients (see Selenium or Chromium monographs).Moyad 2007


Animal data

Research reveals no animal data in the last 10 years regarding the use of the yeast S. cerevisiae in diarrhea. The low toxicity profile of brewer's yeast and widespread use as a food supplement make such data irrelevant.

Clinical data

An open-label trial evaluated the effect of 6 to 50 g daily of fresh baker's yeast in cancer-related constipation. The authors suggest yeast fermentation in the intestine may induce water retention in the lumen similar to that of lactulose or sorbitol.Wenk 2007 The symptomatic treatment of acute diarrhea is an indication for brewer's yeast listed in the German Commission E Monographs.Blumenthal 1998

Immune effects

Animal data

S. cerevisiae–derived beta-glucan has been shown to enhance neutrophil antimicrobial functions in vitro and in animal studies and to reduce staphylococcal abscess formation in a guinea pig model.Bell 1999, Lehne 2006

Clinical data

Clinical trials using yeast-derived beta-glucan are limited. Reviews of the effects of beta-glucan on the immune system have been published for fungal, oat, and barley beta-glucan sources.

Purified, soluble yeast beta-glucan given orally to healthy volunteers increased salivary immunoglobulin A (IgA)Lehne 2006 as did brewer's yeast administered to people with allergic rhinitis.Moyad 2009

Enhanced microbial killing by monocytes and neutrophils has been demonstrated in healthy volunteers after S. cerevisiae–derived beta-glucan (Betafectin ) administration and in surgical patients.Babineau 1994, Dellinger 1999 Postexercise immunosuppression was minimized with baker’s yeast beta-glucan in a randomized, crossover trial (n = 60). Monocyte concentrations (total and pro-inflammatory) and plasma cytokine concentrations were increased compared with baseline after strenuous exercise in healthy college students who were given 250 g/day baker’s yeast beta-glucan supplementation for 10 days prior to strenuous aerobic exercise. Additionally, lipopolysaccharide-stimulated cytokine production increased before exercise, changes that preceded changes in plasma cytokines.Carpenter 2013

Metabolic effects

Animal data

Research reveals no animal data in the last 10 years regarding the use of the yeast S. cerevisiae in metabolic syndrome, hypertension, or diabetes mellitus.

Clinical data

A clinical trial evaluated the effect of brewer's yeast 10 g/day over 12 weeks on the lipid and glucose profile of healthy adults. No difference was found for body weight, blood pressure, and cholesterol. A decrease in serum triglycerides was demonstrated, as well as improvements in the glucose tolerance test.Li 1994 Similarly, total cholesterol was decreased in a study among 15 obese hypercholesterolemic men.Bell 1999

Two small studies used chromium-enriched brewer's yeast in patients with type 2 diabetes mellitus. A double-blind, crossover study (n = 20) compared 8-week treatments with 5 tablets daily of BioChromDIA (brewer's yeast with chromium 100 mcg per tablet) and identical placebo (brewer's yeast with chromium 1 mcg per tablet). The dose of brewer’s yeast in this study was not stated. There were no significant differences between treatments for body mass index, lipid profiles, or hemoglobin A1c (HbA1c).Król 2011 A single-blind, placebo-controlled, 3-month study (n = 40) compared brewer’s yeast 9 g plus chromium 42 mcg to control (plain brewer’s yeast without chromium). Mean reductions in HbA1c, serum triglycerides, and low-density lipoprotein-cholesterol (LDL-C) were significantly greater in the treatment group compared with control.(22) An open-label, 8-week study (n = 55) evaluated the effect of brewer’s yeast 3,600 mg plus chromium 14.4 mcg per day in type 2 diabetes mellitus. A statistically significant reduction in fasting blood glucose was seen at week 8, but not week 4. Statistically significant results were seen at week 4 and week 8 for reductions in triglycerides and LDL-C, and increases in high-density lipoprotein cholesterol.Khosravi-Boroujeni 2012

Respiratory effects

Animal data

An antiviral effect of S. cerevisiae–derived beta-glucan on swine influenza virus has been demonstrated.Jung 2004

Clinical data

A series of double-blind, randomized clinical trials evaluated the effect of S. cerevisiae 500 mg per day over 12 weeks on symptoms of colds in healthy adults. Among immunized participants, a decrease in the incidence and duration of symptoms was demonstrated, while in nonimmunized participants, a decrease in incidence was observed, with no effect demonstrated on duration and severity of symptoms.Moyad 2008, Moyad 2010 The same researchers evaluated the effect of the same commercial product in allergic rhinitis and demonstrated a decrease in nasal congestion and rhinnorhea and an increase in salivary IgA during high pollen-count days. No effect on ocular discharges was demonstrated.Moyad 2009

Other uses

Improved depression scores have been demonstrated after 2 weeks among healthy volunteers using 200 and 500 mg doses of yeast hydrolysate as a gum. Brain mapping after 3 days showed a profile of a stable psychological state.Lee 2009 In animals, brewer's yeast extract decreased the spleen weight and interferon and interleukin activity in mice with induced chronic fatigue syndrome.Takahashi 2006

S. cerevisiae has been evaluated for its effect on skin textureMoyad 2010 and in combination with other natural products for safety and efficacy in HIV patients.Maek-a-nantawat 2009


Upper respiratory tract infections

S. cerevisiae 500 mg daily (as commercially available capsules) has been used in clinical trials over 12 weeks to treat respiratory infections and allergic rhinitis.Moyad 2009, Moyad 2010


6 to 50 g of fresh baker's yeast over 3 days was used in a study for the treatment of cancer-related constipation.Wenk 2000

Acute diarrhea

500 mg daily of brewer's yeast is recommended in the German Commission E Monographs.Blumenthal 1998

Pregnancy / Lactation

Information regarding safety and efficacy in pregnancy and lactation is lacking.


S. cerevisiae contains tyramine, and, although case reports are lacking, concurrent use of yeast supplements with MAOIs should be avoided.Howland 2006, Shils 2006

Adverse Reactions

The use of S. cerevisiae has not been studied in children. It should be avoided in individuals with yeast allergies. Mild adverse reactions have been reported, including flatulence and a laxative effect.Wenk 2000

Increased disease activity has been demonstrated in a study evaluating S. cerevisiae yeast consumption in Crohn disease. The presence of antibodies to the yeast was demonstrated in a portion of study participants.Barclay 1992


Research reveals little information regarding the toxicology of brewer's yeast. At 3 g/kg body weight, no toxic effects were observed in mice or rats.Blumenthal 1998 Brewer's yeast has GRAS status with the FDA.FDA 2011

Purified, soluble yeast beta-glucan manufactured in Norway has shown no mutagenic or chromosomal toxicity, and no acute or delayed toxicity was observed in mice, rats, and pigs after oral or parenteral administration in preclinical studies.Lehne 2006

Index Terms

  • Saccharomyces boulardii
  • Saccharomyces exiguous


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This product may adversely interact with certain health and medical conditions, other prescription and over-the-counter drugs, foods, or other dietary supplements. This product may be unsafe when used before surgery or other medical procedures. It is important to fully inform your doctor about the herbal, vitamins, mineral or any other supplements you are taking before any kind of surgery or medical procedure. With the exception of certain products that are generally recognized as safe in normal quantities, including use of folic acid and prenatal vitamins during pregnancy, this product has not been sufficiently studied to determine whether it is safe to use during pregnancy or nursing or by persons younger than 2 years of age.

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