Brewer's yeast is not the same as the baker's yeast that makes bread rise or the yeast that causes yeast infections. It is just what it sounds like it should be the yeast used in making beer. Because of the different methods used in its culture, it can vary in its nutritional profile; however, it tends to be a good source of several B vitamins and a few minerals: thiamin (B,), riboflavin (B2), niacin (B3), folic acid, pyridoxine (Bfi), B12, chromium (known as glucose tolerance factor [GTF]), copper, iron, and zinc.
Most of the clinical work that has been performed on brewer's yeast has been for its potential use as a source of organic chromium, which has been theorized and confirmed in several studies to improve glucose control and lipid values. It is this application that has led to claims about brewer's yeast being good for reducing blood sugar and cholesterol. One study suggests its beneficial role in athletic recovery. The energy claims made on brewer's yeast are yet unfounded by clinical research.
One product made from brewer's yeast that is not included in this review is called brewer's yeast cell wall. It is a byproduct of producing brewer's yeast extracts and is being promoted as a functional food for modulating the immune system, controlling cholesterol, and promoting healthy intestinal flora (Tomohiko et al, 2000, 2001).
AcneWeber et al. (1989) studied the effects of a maximum of 5 months of brewer's yeast supplementation (Saccharomyces cerevmae Hansen CBS 5926 [Perenterol]) in 139 patients with acne. Physicians' rating of the results on the treatment group was very good or good in 74% of the patients versus 21.7% in the placebo group. In the treatment group that was rated very good or good, 80% of the patients were considered healed or very much better compared with only 26% of the placebo group that was rated very good or good.
Athletic Recovery and Antioxidant
In a nonblinded, controlled study, the effect of an undefined yeast cell preparation (high in antioxidant vitamins, antioxidant enzymes, trace elements, and minerals) on the stress reaction and antioxidant status of nine highly trained athletes was studied. Venous blood samples were drawn and tested in the resting state after an overnight fast followed by a 15-km cross-country race. The treatment with the yeast cell preparation gave an improvement in the systemic and muscular stress reaction, reflected by a lower soluble interleukin-2 receptor and plasma fibrinogen and higher plasma fibronectin in the resting state, and a significant difference in fibrogen and fibronectin 1 hour after the race. Myoglobin, CKMM3, and mangan superoxide dismutase were reduced, reflecting a decrease in free-radical stress (Konig et al., 1999).
Blood Sugar and Diabetes
The effect of daily chromium supplementation (either brewer's yeast containing 23.3 u.g of chromium, or carbon tetrachloride providing 200 u.g of chromium) was tested on glucose tolerance, serum lipids, and drug dosage in 78 type 2 diabetes patients. The study was a double-blind, placebo-controlled, crossover design that lasted 32 weeks. The authors concluded that the supplementation with chromium resulted in better control of glucose and lipid variables, with decreases of drug dosages (to the point that some subjects no longer needed insulin). The brewer's yeast supplementation of chromium increased the time chromium was retained in the body and extended the beneficial effects as a result.
The effect on serum glucose and lipids of brewer's yeast supplementation (10 g/day for 12 weeks) was studied in a controlled (torula yeast) study of 22 Chinese adults. Blood was drawn before the glucose load and at 30-, 60-, 90-, and 120-minute intervals after. The treatment group resulted in decreases in serum triacylglycerol values and in 60- and 90-minute values of oral glucose tolerance testing (Li, 1994).
Rabinowitz et al. (1983) studied the effect of chromium supplementation on carbohydrate utilization in a double-blind, random, crossover trial involving 43 men. This study was conducted because of the observation of diabetes resulting from chromium deficiency in experimental animals and humans during long-term parenteral nutrition. The groups were given either inorganic chromium (chromium trichloride), a brewer's yeast containing GTF (an organic form of chromium), a brewer's yeast not containing GTF, or a placebo. The patients were further split into subgroups of 21 ketosis-prone men, 7 ketosis-resistant nonobese men, and 15 ketosis-resistant obese men. Chromium levels were found to increase In the body pools of the men from treatment with either organic or inorganic forms of chromium by about 25%. Additionally, in the ketosis-resistant subgroups, there was a significant increase in postprandial insulin from treatment with brewer's yeast that contained GTF. No effects were found, however, on carbohydrate metabolism in any of the groups.
In one study of 23 elderly people, the effect on glucose tolerance, insulin, cholesterol, and triglycerid.es of 200 jig of chromium (from chromic chloride), 5 g of brewer's yeast, or placebo supplementation was studied. After 10 weeks, no differences were found among the groups on the measured parameters. Plasma chromium content, however, rose after the supplementation with chromic chloride, but not with brewer's yeast. The authors concluded that age was not a factor leading to chromium deficiency.
Saner etal. (1983) conduced a study of the effect of chromium supplementation (with 30 g/day of brewer's yeast containing 50 iig of chromium) for S weeks on patients with Turner syndrome, which is characterized by a high incidence of diabetes. Chromium- and lipid-value testing suggested that the study patients had chromium deficiencies and that these deficiencies could have a role in the abnormal glucose tolerance tests found in many Turner syndrome patients.
In a small pilot study involving 10 patients with type 2 diabetes, the effect of brewer's yeast supplementation was studied. Eight of the 10 patients showed improvement in glucose tolerance. No significant changes in serum insulin, total cholesterol, or triglycerides were found (Bialkowska etal., 1981).
Glucose control and lipid values were compared after the daily ingestion of either 9 g of chromium-rich brewer's yeast or chromium-poor torula yeast for 8 weeks. The 24 participants in the study were older (mean age of 78 years) and were divided into normal and diabetic subgroups. In the brewer's yeast group, glucose tolerance improved significantly and insulin output was reduced after supplementation. Additionally, cholesterol and total lipids fell after supplementation in this group, with higher decreases in the hypercholesterolemic people. The torula yeast group showed no significant changes in glucose control, insulin, or lipids. Cholesterol was found to have significantly decreased in the subgroup of nondiabetics but not in the diabetic group.
A review of yeast-derived fiber products has suggested that they are a heller source of fi-glucan (a dietary fiber) than are oat products because they are more concentrated; therefore, yeast products may be better dietary additions to lower serum cholesterol levels (Bell et ah, 1999). Apart from being a E-glucan source, brewer's yeast and chromium is known to improve blood lipid values, cholesterol, and triglycerides. Several of these studies have been cited here.
It is important to look at the nutritional content of the brewer's yeast product to verify that it contains GTF (or chromium) if its intended use is for chromium supplementation. Some people report mild gastrointestinal (GI) upsets when first taking brewer's yeast. Starting with small amounts (1/4 teaspoon daily) and increasing as desired (to 1-3 tablespoons daily) can help patients avoid GI upsets. In clinical studies for blood sugar control, from 5-30 g of GTF-containing brewer's yeast was taken daily with beneficial results. No other serious side effects have been noted.