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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

Medically reviewed by Last updated on Sep 30, 2021.

Clinical Overview


Brewer’s yeast is recommended in the German Commission E monographs as treatment for acute diarrhea. Limited data support use for hyperglycemia in type 2 diabetics and upper respiratory tract infections in older adults as well as a beta-glucan-chitin-chitosan extract for weight control in overweight and obese patients.

NOTE: For information on S. cerevisiae variant boulardii(also known as S. boulardii), refer to the Probiotic monograph.


Acute diarrhea: 500 mg daily of brewer's yeast is recommended in the German Commission E Monographs. 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. Much lower doses were used for Hyperglycemia: 68 to 500 mcg/day for 2 to 8 months lowered fasting plasma glucose in patients with type 2 diabetes. Weight management:S. cerevisiaeextract (beta-glucan-chitin-chitosan fraction) 3 g/day suspension for 12 weeks reduced incidence of weight gain, weight, BMI, and waist circrumference in overweight and obese patients.


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

NOTE: For information on S. cerevisiae variant boulardii (also known as S. boulardii), refer to the Probiotic monograph.

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)

Gastrointestinal conditions


Clinical data

An open-label trial evaluated the effect of 6 to 50 g/day 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)

In a pilot study, a dried yeast fermentate made from S. cerevisiae (EpiCor) or placebo was administered for 6 weeks to 80 adults with moderate to severe intestinal discomfort and constipation. Not unexpectedly, a significant placebo effect was observed, particularly in the severe-symptom subgroup of this study. Consumption of EpiCor 500 mg/day produced significant improvements in the moderate-symptom treatment subgroup compared to placebo for bloating/distention (week 2, P=0.033; week 4, P=0.024), feeling of fullness (week 2, P=0.004; week 4, P=0.023), and general GI discomfort (week 2, P=−0.046). By week 6, results were no longer statistically significant. In the severe-symptom subgroup and the total cohort, a significant improvement in stool consistency was observed with EpiCor at week 2 (P=0.046 and P=0.023, respectively), but not at week 4 or week 6. No significant difference was observed between groups for impact of constipation on quality of life or general stress levels. Changes in gut microbiota were also measured; however, changes in diet could have confounded the results as diet was not monitored.(Pinheiro 2017)


Clinical data

The symptomatic treatment of acute diarrhea is an indication for brewer's yeast listed in the German Commission E Monographs.(Blumenthal 1998)

Irritable bowel syndrome

Clinical data

An individual patient data meta-analysis (N=579) assessed the effect of S. cerevisiae (CNCM I-3856 strain) supplementation on GI symptoms in 2 studies of "constipation-type" subpopulations of patients with irritable bowel syndrome (IBS) as well as the intent-to-treat (ITT) group. The constipation subpopulations were categorized as “hard stools at least 25% of the time” or as "abdominal pain score of at least 2 at baseline." No consistent effect was observed with S. cerevisiae supplementation across any of the study groups. Symptom scores and bowel movements improved significantly overall for both the treatment and placebo groups over the 8-week study period. Similarly, no significant differences were identified between the S. cerevisiae and placebo groups in total area under the curve (AUC) for abdominal pain/discomfort or bloating over the 8 weeks for the ITT or the “hard-stool" constipation subpopulation. In contrast, abdominal pain/discomfort AUC was statistically significantly improved from week 0 to week 8 for the “abdominal-pain” constipation subgroup (P=0.0417). During the 2nd month (week 5 to week 8), significant improvements were found in bloating AUC in all groups (P<0.05) and for abdominal pain AUC in all except the "hard-stool” constipation group (P<0.02).(Cayzeele-Decherf 2017)

In a double-blind, randomized, controlled pilot study conducted in 26 adults (96% female) with IBS, consumption of baker's yeast-fermented wheat bread with added gluten (2% flour by weight) compared to sourdough wheat bread resulted in no significant difference in inflammatory markers between groups after 1 week. Similarly, the overall GI symptom scores were not significantly different between groups. However, non-GI-related "other" symptoms became significantly worse in the sourdough group compared to the yeast-bread group; tiredness (P=0.01), joint symptoms (P=0.03), and decreased alertness (P=0.003). The total score for the 5 "other" symptoms was also significantly better with yeast-fermented bread (P=0.02).(Laatikainen 2017)

The American College of Gastroenterology (ACG) clinical guideline for the management of irritable bowel syndrome (2021) suggests that soluble, but not insoluble, fiber be used to treat global IBS symptoms (Strong; moderate).(Lacy 2021)

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) In contrast, no significant change in salivary IgA, or plasma cytokines or chemokines was observed with 90-day administration of a beta-1,3/1,6 glucan supplement derived from S. cerevisiae (Wellmune 250 mg/day) to older community-dwelling adults.(Fuller 2017)

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

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. No significant differences were observed 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.(Sharma 2011) An open-label, 8-week study (n=55) evaluated the effect of brewer’s yeast 3,600 mg plus chromium 14.4 mcg/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) A systematic review and meta-analysis evaluated the effect of chromium supplementation on HbA1c and/or fasting plasma glucose in patients with type 2 diabetes. Pooled data from 4 randomized clinical trials (N=262) using Brewer’s yeast (68 to 500 mcg/day for 2 to 8 months) demonstrated a significant lowering effect on fasting glucose (−19.23 mg/dL; 95% confidence interval [CI] −35.30 to −3.16 mg/dL; low heterogeneity) but not on HbA1c when compared to placebo.(Yin 2015)

A multicenter, double-blind, randomized, placebo-controlled study in 56 overweight or obese adults studied the effects on weight loss of an investigational polysaccharide-rich hydrolysate from S. cerevisiae that contained a beta-glucan-chitin-chitosan fraction (BGCC). Participants received the intervention (BGCC 3 g/day suspension) or placebo for 12 weeks, after which only 35% in the BGCC per-protocol group experienced weight gain compared to 80% in the placebo group (P=0.003). The change between groups in reduced weight, BMI, and waist circumference was statistically significant (P=0.006, P=0.000, and P=0.049, respectively). No significant differences were observed in any of the other 21 anthropomorphic, plasma lipid, metabolic, laboratory, or physical activity measures. One participant in the BGCC group discontinued the study due to the treatment-related adverse effect of flatulence.(Santas 2017)

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)

A beta-1,3/1,6 glucan supplement derived from S. cerevisiae (Wellmune 250 mg/day) or placebo was administered for 90 days to older community-dwelling adults in a double-blind, randomized, controlled trial (N=100). No significant difference was observed between groups in the incidence of upper respiratory tract infections (URTI) even when adjusted for influenza vaccine uptake and smoking status. Additionally, no difference was found between groups in URTI symptom severity, salivary IgA concentrations, or plasma cytokines or chemokines. Adverse effects were more common in the placebo group.(Fuller 2017)

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


Acute diarrhea

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


Brewer’s yeast 68 to 500 mcg/day for 2 to 8 months lowered fasting plasma glucose in patients with type 2 diabetes.Yin 2015

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

Weight management

S. cerevisiae extract (beta-glucan-chitin-chitosan fraction) 3 g/day suspension for 12 weeks reduced incidence of weight gain, weight, BMI, and waist circrumference in overweight and obese patients.Santas 2017

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 cerevisiae var boulardii
  • Saccharomyces exiguous



This information relates to an herbal, vitamin, mineral or other dietary supplement. This product has not been reviewed by the FDA to determine whether it is safe or effective and is not subject to the quality standards and safety information collection standards that are applicable to most prescription drugs. This information should not be used to decide whether or not to take this product. This information does not endorse this product as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this product. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to this product. This information is not specific medical advice and does not replace information you receive from your health care provider. You should talk with your health care provider for complete information about the risks and benefits of using this product.

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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Further information

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