Saccharomyces cerevisiae, which in Latin means
“sugar fungus,” has been utilized by humans for
thousands of years. It is believed that it was
first discovered on the skins of grapes. S.
cerevisiae is a budding or brewing yeast, and
has been put to use since antiquity to make
dough rise and to provide ethanol in alcoholic
beverages. One of the most elemental purposes of
brewers yeast was that it transformed the way
bread was made in ancient times. Once, all bread
was unleavened, and could often have a hard, dry
texture. One can only imagine the reaction when
yeast was accidentally added to the bread
mixture an estimated 5,000 years ago in Egypt,
yielding a chewy, flavorful diet staple. (1)
Yeast remains a key component in baking to this
day. The pioneering research of Louis Pasteur in
the 1860s included a method of enabling yeast to
be commercially produced as an ingredient for
baking and in the processing of alcoholic
Its deeply detailed cellular structure makes S.
cerevisiae, also known as "brewers yeast," one of the most highly researched
model organisms in the study of biology. It
exists in single-cell form, or in pseudomyceliac
form. Cellular reproduction occurs by budding.
The ability of S. cerevisiae to ferment specific
sugars is a major factor that differentiates it
from other yeasts.
S. cerevisiae exists and grows in the haploid
and diploid cellular forms. The haploid life
cycle consists of mitosis, growth, and
ultimately death, the latter more rapid under
extremely stressful conditions. Diploid cells
also undergo mitosis as well as growth, but in
the same stressful circumstances can experience
sporulation. Subsequent to sporulation, the
cells undergo meiosis and produce a number of
haploid spores. These haploid spores progress to
Benefits of S. Cerevisiae:
A probiotic in terms of its beneficial effects,
S. cerevisiae has many properties from the most
basic to highly advanced. When ingested in a
quantity of two tablespoons daily, the
commercially prepared product known as
“nutritional yeast” provides 52 percent of the
recommended daily amount (RDA) of protein.
Nutritional yeast is also high in fiber, B
vitamins and folic acid. It is also gluten-free,
which makes it an attractive supplement to
people who are wheat-intolerant.
Nutritional yeast also has the presence of
beta-1,3 glucans, which have been shown to
stimulate the body’s immune system. Researchers
at the University of Louisville established a
receptor found on the surface of certain immune
cells is known for binding itself to beta-glucans,
which permits the immune cells to recognize the
beta-glucans as being dissimilar. (2) While some
pharmaceutical drugs are capable of
over-stimulating the body’s immune system during
therapy and are therefore not suitable for
people with autoimmune illnesses, beta-glucans
appear to assist the immune system without
causing overactivity (3). Beta-glucans are also
apparently capable of lowering LDL cholesterol
levels, assisting in the healing of wounds and
aid in the prevention of infections.
Beta-glucans derived from shiitake mushrooms
have been applied as immunoadjuvant treatment
for cancers since 1980. This therapy is
particularly popular in Japan. Several studies
indicate that beta-glucans can prevent the
formation of tumors and the development of
cancers. (4,5,6) In an experiment conducted with
mice, beta 1,3 glucans administered with
interferon gamma slowed the progress of tumors
and metastasis to the liver. (7) It was also
proved that among human colorectal cancer
patients, ingestion of beta-1,3 glucans from
shiitake mushrooms, along with chemotherapy,
generated a longer rate of survival. (8)
Prepared yeast is also easily stored. Often
vacuum-packed or sealed in individual doses,
this form of S. cerevisiae is shelf-stable for
approximately one year.
Safety of S. Cerevisiae:
People have contact with S. cerevisiae daily,
whether by way of inhalation or ingesting it as,
perhaps, as health supplement This
"brewers yeast" has a long track record of
safety. Studies were
conducted in 1961 to determine whether consuming
large quantities of S. cerevisiae would produce
a result of colonization of the yeast, or its
transmission to other body organs. The studies
showed that extremely high consumption of S.
cerevisiae would result in passage and
colonization to draining of the lymph nodes.
However, a large feeding of approximately ten S.
cerevisiae in one dose administered to
laboratory rats was needed to achieve a
noticeable passage to the rats’ lymph nodes.
This was found to be quite in excess of the S.
cerevisiae encountered on a normal daily basis.
While S. cerevisiae is not generally regarded as
an infective agent, a few isolated incidents
listed the yeast as a factor in certain
infections. Studies conducted in 1984 (10)
indicated S. cerevisiae as being at least
partially culpable in causing infections in
patients. However, all of the patients observed
had underlying health problems, and some had
ingested antibiotics that killed off beneficial
bacteria, giving rise to the mycotic organisms.
S. cerevisiae does not produce toxins that are
harmful to humans or animals. However, it is
capable of producing what are known as “killer
toxins” that are fatal to other yeasts. S.
cerevisiae is sometimes used in food and
beverage preparation facilities to control the
contamination of fermentation production areas
by other kinds of yeasts.
In very rare cases, S. cerevisiae causes vaginitis.
According to a 1999 article in the Journal of
Clinical Microbiology, a small but increasing
number of isolations of S. cerevisiae were found
in women of childbearing age. In a study
conducted among these women, DNA typing isolated
the yeast in women who had vaginitis symptoms,
or who were asymptomatic. (11)
(1) "The History of Bread Yeast,” British
Broadcast Corporation, 2006.
(2) Vetvicka, V., Thornton B.P., Ross G.D.
(1996-07-01). "Soluble Beta-Glucan
Polysaccharide Bnding to the Lectin site of
Neutrophil or Natural Killer Cell Complement
Receptor Type 3 (CD11b/CD18) Generates a Primed
State of the Receptor Capable of Mediating
Cytotoxicity of iC3b-opsonized Target Cells.”
The Journal of Clinical Investigation (United
States: American Society for Clinical
Investigation) 98 (1): 50–61.
(3) Chihara, G. (1992). "Recent Progress in
Immunopharmacology and Therapeutic Effects of
Polysaccharides.” Developments in Biological
Standardization, 77: 191–197.
(4) DiLuzio, N.R.; Williams D.L., McNamee R.B.,
Malshet V.G. (1980). "Comparative Evaluation of
the Tumor Inhibitory and Antibacterial Activity
of Solubilized and Particulate Glucan.” Recent
Results in CancerResearch. Fortschritte der
Krebsforschung. Progrès dans les Recherches sur
le Cancer 75: 165–172. ISSN 0080-0015.
(5) Morikawa, K., Takeda, R., Yamazaki, M.,
Mizuno, D, (April 1985). "Induction of
Tumoricidal Activity of Polymorphonuclear
Leukocytes by a Linear Beta-1,3-D-Glucan and
other Immunomodulators in Murine Cells.” Cancer
45 (4): 1496–1501.
(6) Mansell, P.W., Ichinose, H., Reed, R.J.,
Krementz, E.T., McNamee, R., Di Luzio, N.R.
(March 1975). "Macrophage-Mediated Destruction
of Human Malignant Cells in Vivo.” Journal of
the National Cancer Institute 54 (3): 571–580.
(7) Sveinbjørnsson, B., Rushfeldt, C., Seljelid,
R., Smedsrød, B. (May 1998). "Inhibition of
Establishment and Growth of Mouse Liver
Metastases after Treatment with Interferon Gamma
and Beta-1,3-D-Glucan.” Hepatology 27 (5):
(8) Wakui, A., Kasai, M., Konno, K., Abe, R.,
Kanamaru, R., Takahashi, K., Nakai, Y., Yoshida,
Y., Koie, H., Masuda, H., et al. (April 1986).
"Randomized study of lentinan on patients with
advanced gastric and colorectal cancer. Tohoku
Lentinan Study Group" (in Japanese). Gan to
kagaku ryoho. Cancer & chemotherapy (Japan: Gan
To Kagaku Ryohosha) 13 (4 pt 1): 1050–1059
(9) Wolochow, H., Hildegrand, G.J,, and Lamanna,
C. (1961). “Translocation of microorganisms
across the intestinal wall of the rat: effect of
microbial size and concentration.” Journal of
Infectious Diseases 116: 523-528.
(10) Eng, R., Drehmel, R., Smith, S. and
Goldstein, E. (1984). “Saccharomyces Cerevisiae
Infections in Man,” Medical Mycology 1984, 22,
No. 5: 403-407.
(11) Posteraro, B., Sanguinetti, M., D’Amore,
G., Masucci, L., Morace, G. and Fadda, G. (July
1999). ”Molecular and Epidemiological
Characterization of Vaginal Saccharomyces
Cerevisiae Isolates,” Journal of Clinical
Microbiology, 37 (7): 2230-2235.
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