Equol was discovered in the 1980s; it is bacterially derived from daidzein, an isoflavone abundant in soy foods. Unlike the soy isoflavones, daidzein or genistein, it has a chiral center and therefore can occur as 2 distinct diastereoisomers, R and S. Humans have acquired an ability to exclusively synthesize S-equol from daidzein, and it is significant that, unlike R-equol, the S enantiomer has a relatively high affinity for estrogen receptor beta. A newly isolated rod-shaped, gram-negative anaerobic bacterium from human feces, named Julong 732, was found to be capable of metabolizing the isoflavone dihydrodaidzein to S-equol under anaerobic conditions.
Isoflavones - Daidzen and Genistein, 1000 mg
tablets, by
Source Naturals
Isoflavones derived from soybeans have been the focus of scientific research for
several decades. Studies have shown that isoflavones can bind to the same
receptor sites as estrogen. Soybeans are a significant dietary source of
isoflavones; however, the amount of soy foods necessary to meet the body's
needs can be difficult to incorporate into today's diet. In Asia, where
soy is a staple, the daily isoflavone intake can be up to 20 times that of
a Western diet. Source Naturals isoflavone-rich soybean powder yields a
consistent standardized isoflavone content. This unique chemical-free
process requires approximately 400 pounds of soybeans to yield just one
pound of finished product.
Supplement Facts:
Isoflavone-Rich - 2 g
Soybean Powder (Soylife) Yielding:
Daidzein - 34 mg - converts into equol
Glycitein - 20 mg
Genistein - 8 mg
Total Isoflavones - 62 mg
Equol and hair loss or growth
As of 2015, I am not aware of good research with equol supplements
to determine if this nutrient has an influence on hair growth or is as
effective in vivo DHT blocker.
Will producing equol potentially help with male pattern baldness? If
equol is created by soy plus something, what is the something that
provides the bacteria environment for it? Is green tea that missing
factor?
Long term human studies are required to determine the role of equol in male pattern baldness, not enough research is available at this
time to know its role in hair growth. It appears that vegetarians
have a higher levelin their body, but the
specific fruits, vegetables, legumes, etc that influence this is not yet
clear to me.
Breast cancer
BMC Cancer. 2013. Equol enhances tamoxifen's anti-tumor activity by
induction of caspase-mediated apoptosis in MCF-7 breast cancer cells.
Cervical cancer
Anticancer Res. 2014. Equol induces mitochondria-mediated apoptosis
of human cervical cancer cells.
Prostate cancer
I am not aware of human clinical studies with equol supplements regarding the
prevention or treatment of prostate cancer.
Asian Pac J Cancer Prev. 2013. Influence of isoflavone intake and equol-producing intestinal flora on prostate cancer risk. A traditional Japanese meal, high in soybean products or isoflavones, may be associated with a decreased risk of PCa. Equol, which is converted from daidzein by human intestinal flora, is biologically more active than any other isoflavone aglycone. We reviewed not only recent epidemiological studies on association of isoflavones with PCa risk, but also recent research on human intestinal bacteria responsible for converting daidzein into equol. Studies were systematically searched from the database published within the last 5 years of from 2008-2012. Five out of 6 articles showed significant association of isoflavones with a decreased risk of PCa, and two of them consistently showed that equol-producers carry a significantly reduced risk of PCa. Furthermore, 5 human intestinal bacteria that can convert daidzein into equol were identified in the last 5 years. If equol can reduce risk of PCa, a possible strategy for reducing the risk of PCa may be to increase the proportion of equol-producers by changing the intestinal flora to carrying an equol-producing bacterium with dietary alteration or probiotic technology.
Vegetarians
Method of defining equol -producer status and its frequency among
vegetarians.
J Nutr. 2006.
7-Hydroxy-3-(4'-hydroxyphenyl)-chroman ( S- equol ) is a specific
end-metabolite formed in the biotransformation of the dietary soy
isoflavones daidzin and daidzein by intestinal bacteria. The frequency of
equol production varies among individuals and populations, and it is
suggested that the efficacy of soy foods differs depending on the ability
of an individual to produce equol. To develop a standardized approach to
define equol -producer status that can be universally adopted to
differentiate these 2 distinct populations, we measured isoflavones in
serum and urine collected from a cohort of 41 healthy adults, comprising
29 vegetarians
and 12 nonvegetarians, after consuming 2 x 250 mL/d soy milk on 3
consecutive days. The frequency of equol producers in the vegetarians was
59%, similar to the reported frequency in Japanese adults consuming soy,
and much higher than for nonvegetarian adults (25%), suggesting that
dietary components other than soy influence equol synthesis by intestinal
bacteria.
Bioavailability, absorption
and physiology
The nonsteroidal estrogen equol occurs as diastereoisomers, S and R, both of which have significant biological actions. S-(–)equol,
the naturally occurring enantiomer produced by 20–30% of adults
consuming soy foods, has selective affinity for estrogen receptor-β,
whereas both enantiomers modulate androgen action. Both enantiomers are
rapidly absorbed, attain high circulating concentrations, and have a
similar terminal elimination half-life of 7–8 h. American Journal of
Clinical Nutrition, October 2009.
Equol research
S-Equol, a potent ligand for estrogen receptor ß, is the exclusive
enantiomeric form of the soy isoflavone metabolite produced by human intestinal
bacterial flora.
American Journal of Clinical Nutrition, 2005
Because it was unclear which enantiomer was present in humans, our objectives
were to characterize the exact structure of equol, to examine whether the S- and
R-equol enantiomers are bioavailable, and to ascertain whether the differences
in their conformational structure translate to significant differences in
affinity for estrogen receptors. Results: Our studies definitively establish S-equol
as the exclusive product of human intestinal bacterial synthesis from soy
isoflavones and also show that both enantiomers are bioavailable. S-equol has a
high affinity for estrogen receptor ß, whereas R-equol is relatively inactive.
Conclusions: Humans have acquired an ability to exclusively synthesize S-equol
from the precursor soy isoflavone daidzein, and it is significant that, unlike
R-equol, this enantiomer has a relatively high affinity for estrogen receptor
beta.
Gut bacterial metabolism of the soy isoflavone daidzein:
exploring the relevance to human health.
Exp Biol Med. 2005.
Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North, Seattle, WA
The indigenous intestinal microflora are involved in a variety of processes
within the human body, and are important for maintaining host health. As such,
interindividual differences in the ability to harbor certain intestinal bacteria
might be associated with interindividual differences in health and/or disease
susceptibility. In the last decade there has been considerable interest in
phytoestrogen intakes in relation to human health. Daidzein, an isoflavone
phytoestrogen found in soy, is metabolized to equol and O-desmethylangolensin
(O-DMA) by intestinal bacteria. The specific bacterium/bacteria responsible for
equol and O-DMA production in humans have yet to be identified definitively, but
in vitro and animal studies have suggested that equol and O-DMA are more
biologically active than their precursor daidzein. Interestingly, substantial
interindividual differences in daidzein metabolism exist; following soy or
daidzein consumption, approximately 30%-50% of the human population produce
equol, and approximately 80%-90% produce O-DMA. Observational and intervention
studies in humans have suggested that the ability to produce equol and O-DMA may
be associated with reduced risk of certain diseases including breast and
prostate cancers.
Higher consumption of green tea may enhance equol
production.
Asian Pac J Cancer Prev. 2003.
Our previous case-control study revealed that Japanese living
in Japan and Koreans living in Korea can be divided into equol producers
who have an ability to metabolize daidzein to equol and non-producers, and
that the incidence of prostate cancer is higher in the latter group. In
the present study, we examined relationships between type of food intake
and the capacity for equol production in Japanese subjects. The
subjects were the individuals analyzed for the ability to produce equol in
our previous study and newly registered cases. From 2000 to
2002, 276 hospitalized patients were interviewed face-to-face and
blood samples were collected before breakfast. These included 122 patients
with prostate cancer and 154 age-matched controls. The frequency
of equol producers (0.5 ng/ml or more) among cases and controls was 29%
and 45%, respectively. The consumption of soybeans and green
tea were significantly higher in equol producers than in the non-producers. By contrast, the consumption of selenium and fiber was
significantly lower in equol producers. Our results
suggest that higher consumption of soybean and green tea are strongly
related to the establishment of a capacity for equol production.
Estrogenicity of the isoflavone metabolite equol
on reproductive and non-reproductive organs in mice.
Biol Reprod. 2004.
Equol, a metabolite of the phytoestrogen daidzein, is present at
significant levels in some humans who consume soy and in rodents fed
soy-based diets. Equol is estrogenic in vitro, but there have been limited
studies of its activity in vivo. We evaluated equol effects on
reproductive and non-reproductive endpoints in mice. Our results indicate
that equol
is a weak estrogen with modest effects on endpoints regulated by estrogen
receptor alpha when present at serum levels seen in rodents fed soy-based
diets, but quantities present in humans may not be sufficient to induce
estrogenic effects, although additive effects of equol with other
phytoestrogens may occur.
Comparisons of percent equol producers between
prostate cancer patients and controls: case-controlled studies of
isoflavones in Japanese, Korean and American residents.
Jpn J Clin Oncol. 2004.
Our previous case-control study revealed that the Japanese
residents in Japan could be divided into those who are able to degrade daidzein, a soybean isoflavone, to equol and those without this ability,
and that the incidence of prostate cancer is higher in the latter group.
We recently conducted a similar case-control study involving not
only Japanese residents in Japan but also Korean residents in Korea. The
incidence of prostate cancer in Korean residents is known to be close to
that of Japanese residents in Japan. On the other hand, American residents
in the United States have a markedly higher incidence of prostate cancer
as compared to Japanese residents in Japan. The number of
subjects was 295 in Japan (133 patients and 162 controls), 122 in Korea and 45 in the United States (24 patients and
21 controls). The percentage of equol producers among patients and
controls was 29% and 46% in Japan and 30% and 59% in Korea, respectively. The active isoflavone level was markedly lower and
the percentage of equol producers was also lower (17% for patients and 14%
for controls) for Americans as compared to the Japanese and Koreans.
These results suggest that the ability of producing equol is closely related to the lower incidence of prostate cancer.
The results also suggest that a diet based on soybean isoflavones will be
useful in preventing prostate cancer.