How diet affects acne

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Diet and Acne

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 causes acne. Research literature is at best pseudo-scientific and has only generated more myths. Irrefutable evidence based on good quality research is still lacking, making any conclusive statement on the link between diet and acne impossible. This article therefore represents a survey of currently held opinions at best and do not have any hard evidence to support it.

Acne and diet link

The link between diet and acne has largely stemmed from the lower incidence of acne among non-western societies as compared to western societies. Also 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 different ethnicities.

The Hyperinsulinemia theory

High fat and carbohydrate dietary intakes over long periods of time in western societies lead to increased blood glucose levels. In order to normalize the blood sugar levels, the body tends to produce increasing amount of insulin, a condition called hyperinsulinemia. Current evidence shows that women with polycystic ovarian syndrome, a disease associated with hyperinsulinemia, have increased androgen production and decreased production of sex hormone binding globulins (SHBG) in the liver. This leads to a vicious circle wherein this increased androgen leads to decreased SHBG levels. SHBG effectively reduces androgen hormone activity, hence decreased levels increase androgenic actions. The increased androgens also increase insulin resistance, i.e. decrease the ability of the insulin to reduce blood glucose leading to increased levels of insulin requirements to produce the same effects.

Thus, many believe that hyperinsulinemia, caused by may be causing acne by stimulating androgen production and affecting the sebaceous glands and follicular keratinization.

Dietary influence on sebum composition and secretion rate

Pappas et al. convincingly showed that sebaceous glands can and do use fatty acids from the bloodstream for the production of sebum. Some animal studies showed an increase in sebaceous gland production on feeding them a high fat or carbohydrate diet, where as caloric deprivation i.e. starvation has shown changes in sebum composition and reduction in sebum production by up to 40%.

Interventional studies

However other evidence suggests that diet and acne are not linked. 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. In another study, no difference in sugar consumption was found in the group with acne compared with those without acne. More importantly, a 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.

Can chocolate cause acne?

In 1969, a controlled study was done to prove or disprove the connection between chocolate and acne. 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. 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 conversion of comedones to inflammatory pustules was not noted and not considered important in this study. This was an important criticism, since patients with food related acne first complain of pustular flares and not comedones.

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 diet. Larger more randomized studies need to be performed before the link between diet and acne can be completely delineated.

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