Scientific Name(s): Saccharomyces cerevisiae
Common Name(s): Yeast , Baker's yeast , Brewer's yeast , dried yeast fermentate , EpiCor , Fibercel , Betafectin
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, there is a lack of quality trials.
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 baker'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.
Mild GI symptoms, including flatulence.
Information is limited. Baker'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 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. 1 , 2
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 vitamin B 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. 1 , 2 , 3
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 (B 1 ), riboflavin (B 2 ), niacin (B 3 ), pantothenic acid (B 5 ), pyridoxine (B 6 ), folic acid (B 9 ), and biotin (B 7 ). However, brewer's yeast does not contain vitamin B 12 and, therefore, does not fully substitute for the vitamins missing from a vegetarian diet. 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. 3 , 4 , 5 , 6
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). 2Diarrhea
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 unimportant.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. 7 The symptomatic treatment of acute diarrhea is an indication for brewer's yeast listed in the German Commission E Monographs . 1Immune effects
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. 6 , 8Clinical 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 (see Beta-glucan).
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. 10 , 11Metabolic syndrome
Research reveals no animal data in the last 10 years regarding the use of the yeast S. cerevisiae in metabolic syndrome, hypertension, or diabetes.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 triacylglycerol was demonstrated, as well as improvements in the glucose tolerance test. 12 Similarly, total cholesterol was decreased in a study among 15 obese hypercholesterolemic men. 6Respiratory effects
An antiviral effect of S. cerevisiae –derived beta-glucan on swine influenza virus has been demonstrated. 13Clinical data
A series of double-blind, randomized clinical trials evaluated the effect of S. cerevisiae 500 mg 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. 14 , 15 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. 9Other 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. 3 In animals, brewer's yeast extract decreased the spleen weight and interferon and interleukin activity in mice with induced chronic fatigue syndrome. 5
DosageUpper respiratory tract infections
6 to 50 g of fresh baker's yeast over 3 days was used in a study for the treatment of cancer-related constipation. 7Acute diarrhea
500 mg daily of brewer's yeast is recommended in the German Commission E Monographs . 1
Information regarding safety and efficacy in pregnancy and lactation is lacking.
The use of S. cerevisiae has not been studied in children. It should be avoided in individuals allergic to yeast. Mild adverse reactions have been reported, including flatulence and a laxative effect. 7
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. 19
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. 1 Brewer's yeast has GRAS status with the FDA. 20
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. 8
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20. US Food and Drug Administration. Partial list of microorganisms and microbial-derived ingredients that are used in foods. http://www.fda.gov/Food/FoodIngredientsPackaging/ucm078956.htm . Updated June 22, 2009. Accessed April 11, 2011.
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