Way back in the 1950s, any popular food eaten by a teenager was
made to be the cause of acne. This was despite a lack of actual
research evidence available at the time to actually prove diet
and acne were linked. The situation has changed relatively little
since then. Several studies have shown that 30% to 40% of teenagers,
medical students, doctors and nurses, still believe that diet
Such beliefs are due to overwhelming interest generated by the
media about a link between diet and health. This obsessive concern
for health has spurred more research on nutrition bringing the
subject into mainstream medicine. But, due to overriding commercial
concerns, much of the research literature is pseudo-scientific
and has only generated more myths. Today, irrefutable evidence
based on good quality research is still lacking, making any conclusive
statement on the link between diet and acne impossible. At most,
a survey of currently held opinions can be given. People’s
perceptions are, however, important since treatments are often
based on such perceptions.
Acne and diet link
The link between diet and acne is believed to be shown by the
lower incidence of acne among non-western societies as compared
to western societies. Also cited as evidence is the fact that
when non-western societies migrate to a western life style the
incidence of acne goes up. A good example is the Inuit Indians
of Canada, among whom acne was absent when they lived in their
traditional way. On adopting a western life style, acne incidence
among the Inuits reached the levels seen in Western Caucasian
societies. Similar observations have been noted in studies on
other populations of different ethnicities.
Hyperinsulinemia effect on acne
Chronic hyperinsulinemia may be a key link between acne and diet,
high testosterone levels and low levels of molecules called sex
hormone binding globulins (SHBG). SHBG is antagonistic to testosterone,
binding to free molecules of testosterone and rendering it inactive.
So having more SHBG effectively reduces androgen hormone activity.
At one level, the androgen testosterone may be maintaining insulin
levels. At another level they may be promoting insulin resistance.
Considerable evidence now shows that in women with polycystic
ovarian syndrome, hyperinsulinemia increases androgen production
and decreases production of SHBG in the liver. Thus, a vicious
circle is created where this increased androgen leads to decreased
SHBG, further promotes insulin resistance leading to increased
Many believe that hyperinsulinemia, caused by high fat and carbohydrate
diets in western societies may be causing acne by stimulating
androgen production and affecting the sebaceous glands and follicular
Dietary influence on sebum composition and secretion rate
The interpretation of studies on the effect of dietary carbohydrates
and fats on sebum composition and secretion is confusing, but
some general themse seem to be emerging. Some animal studies showed
an increase in sebaceous output on feeding them a high fat or
carbohydrate diet. Studies on humans showed changes in sebum composition
and 40% reduction in sebum secretion, on total and prolonged calorie
A long held opinion that sebaceous glands produced their own
fluids and did not draw anything from the bloodstream was proved
wrong by Pappas et al. They convincingly showed that sebaceous
glands can and do use fatty acids from the bloodstream for the
production of sebum. However, these studies do not conclusively
prove that diet affects sebum composition and secretion.
In general these results suggest that dietary fat and carbohydrate
might have an effect on sebaceous gland activity. However other
evidence suggests that diet and acne are not linked (see below).
Studies on groups under different dietary regimes did not show
any correlation between acne and diet. A study on 2720 soldiers
showed no link between acne and obesity in adolescents although
the study did find a link among older subjects. In another study,
no difference in sugar consumption was found in 16 subjects with
acne and matched controls wiothut acne. An important and large
study conducted on monozygotic and dizygotic twins found no significant
differences, in weight, height, birth weight, body mass index
and reproductive factors, between acne and non-acne affected twins.
Chocolate - a cause?
In 1969, a controlled study was done to find out the truth or
otherwise of chocolateand its effect on worsening the acne condition.
For one month 65 subjects with moderate acne daily ate one bar
containing ten times the chocolate contained in a normal bar or
ate a similar one that contained no chocolate. After measuring
the acne in the study volunteers, the authors concluded that chocolate
did not significantly affect the acne condition.
However, critics found serious methodological flaws in the study.
Most importantly, only changes in the number of lesions were considered
for significance. The qualitative clinical changes like conversion
of comedones into pustular flares were totally ignored. This meant
that conversion of 10 comedones into 10 pustules was not a significant
change for the study. Usually, patients with food related acne
first complain of pustular flares and not comedones. The critics
have a case, but larger scale, better designed studies have not
In conclusion it must be said that, based on the present state
of evidence, the jury is still out on the link between acne and