The present study has provided interesting results regarding
the effects of dried brewer’s yeast on the skin. Yeast first improved
moisture content of the skin, and second improved elasticity. For
moisture content, the significant improvement in the subjective
symptom “desiccated and gritty skin” was supported by the
improved moisture content of skin as determined by SKI and PSI.
This finding appears highly reliable, since dose-dependence was
confirmed in the 3 groups, i.e. the control group as well as Groups
E-9 and E-30. For elasticity, measurements with a Cutometer and
SKI confirmed the significant improvement in elasticity. Among
Cutometer-related parameters, results showed that the most
reliable, R2, was significantly different between Group E-30 and
the control group at 8 weeks, which also supports the reliability of
these findings.
Very few studies have investigated the effect of yeast on skin,
and no report could clearly explain the mechanism of
improvement in moisture content and elasticity. Yeast extract from
Saccharomycopsis was reported to inhibit, via gene expression of
heme-oxigenase-1, the nitric oxide from macrophages, thus
preventing the damage of epidermal cells 24). Antioxidant-enriched
yeast may promote the ability of regeneration and protect the skin
against doxorubicin toxicity 25). These results indicate that the
supplementation of yeast as an anti-oxidant may prevent the
damage of epidermal cells and enhance the ability of tissue
regeneration. It is also possible to prevent the oxidative damage of
collagen which plays a role to keep the skin elasticity. When the
regeneration of the skin is activated, it also promotes the synthesis
of collagen and ceramide which acts as a skin moisturizer. This
may be a reason that the dried brewer’s yeast improved the skin
elasticity and moisture amount in this study. In healthy adult men
who used skincare cosmetics containing hydrolyzed yeast for 2
weeks, evaluation of effects on the skin by skin imaging revealed
improvements in crows feet (wrinkles and stickiness at the corner
of the eye) 26). This result is compatible with the present findings.
Comparison of skin color before and after the study showed
an improvement in Group E-30 in the volume of melanin and
lightness. This finding suggests that some ingredients of dried
brewer’s yeast, which include glutathione (γ-glutamine
cysteinylglycine: GSH), biotin, nicotinic acid (niacin), vitamin B12
and essential amino acids such as tryptophan, are involved in the
effects of yeast on the skin 27-30). Among these substances, GSH in
particular decreases with aging 31) and is involved in the
proliferation and differentiation of neurocytes 32). GSH deficiency
induces neurodegeneration through oxidative stress 33), and GSH is
decreased in patients with Alzheimer disease 34). More recently, its
effect as a depigmenting agent has been reported 35).
Biotin is essential to the maintenance of healthy skin and
wound healing 36,37). Biotin deficiency induces skin diseases or
alopecia 38,39).
Tryptophan is involved in the synthesis of melanin, which has
an antioxidant effect 40,41). In the skin, it has been reported that
melanin protects the skin against ultraviolet rays 42,43) and reduces
pigmentation so as to produce bright-looking skin 44).
The state of the skin generally reflects the physical status such
as gastrointestinal function. In the state of constipation, the
amount of fermenting and degenerated products in intestines
increases. These products shift into blood, and it becomes a cause
to deteriolize the skin function 45). The brewers dried yeast is
shown to improve the bowel movement 46,47). It is also reported
that the dry yeast addition yogurt intake improves the intestinal
environment of bacterial flora 48). These factors maybe play a role
in contributing to the improvement of skin function, although
“constipation” score was not significantly changed in this study.
A serious side effect is not reported to the cellulose crystalline
used as a placebo. It can explain the data change seen in the
control group by the climatic difference. The skin test was done in
March, April, and May. Meanwhile, the rise in the temperature and
humidity, and the increase of durations of sunshine and the amount
of ultraviolet rays were admitted (Table 2) 23). Especially, an
increase of UV-B causes various troubles in the skin 49). In this
study, the melanin amount in control showed significant increase
(Table 4), and the skin elasticity seemed affected (Fig.3) although
it was not significant. Also in the previous study performed in June,
July and August 16), the increased UV sure caused the
augmentation of pigmented lesions and melanin amount. The skin
moisture amount in control seemed affected (Fig.1) in relation to
the rise of humidity, however, it was not significant.
On the other hand, in E-30 group, it is possible that effect is
counterbalanced due to such a disadvantageous condition. Thus, a
significant ameliorating effect might not have been in this study.
The melanin amount admitted a significant increase due to the UV
effect, however the lightness (L*) improved significantly by the
skin color test. It is thought that the lightness improved to the
extent that redness (a*) improves it, because this test is caught
overall in the skin color tone.
During the present study period, 2 subjects prematurely
discontinued the study due to contact dermatitis in one subject in
Group E-9 and photosensitivity in the second in Group E-30. In
both subjects, these events were rated as “unrelated” to the study
product since they were highly incidental. Throughout the study
period, no serious adverse events were noted in the study subjects,
including these discontinuations. Although skin symptom score
“glossless and easily broken nails” has increased significantly in
E-30 group, we did not judge it as a side effect. The reason is that
the extent was negligible and the score rose to the same level as in
control group.
In conclusion, 8-week treatment of premenopausal women with
dried brewer’s yeast at 7,125mg/day produced a significant improvement
in the subjective symptoms “cold skin,” “menstruation-related
troubles,” “make-up runs easily” and “desiccated and gritty skin.”
Further, skin analysis demonstrated a significantly increased
moisture content (about 15%), improved elasticity, and an improved
hemoglobin index. These effects in improving moisture content and
skin elasticity were dose-dependent. Findings suggestive of
unfavorable effects were increased scores for the subjective
symptoms of “blurred vision,” “inability to solve problems,” and
“glossless and easily broken nails,” and an increased volume of
melanin, as determined by skin analysis, although no serious
adverse events were noted. These results indicate the possibility
that treatment with the study product may be useful in improving
both skin condition and QOL. Brewer’s yeast is a natural
substance containing high levels of nutrients such as protein,
carbohydrates, lipids, minerals, vitamins and dietary fiber, as
shown in Table 1. In the future, brewer’s yeast is expected to be
useful in a variety of fields, since it contains these ingredients in
well-balanced combinations.