Acne

Acne

Acne is a skin condition that affects many teenagers and in a small number of cases it may occur in adulthood. About 80 per cent of people will have some degree of acne between the ages of 11 and 30 (NHS Direct, 2005). Acne can be a very serious problem causing distress and depression in some sufferers who report feeling suicidal because of bullying or lack of self-confidence.

Acne is caused by a combination of factors. Hormonal changes can increase the secretion of an oily substance called sebum from the skin’s sebaceous glands which are frequently located adjacent to hair follicles. If skin cells build up and block the opening of hair follicles, subsequent clogging of the sebaceous gland can contribute further to the development of acne. The problem is often made even worse by the colonisation of the skin by the bacterium Propionibacterium acnes which can become trapped in the hair follicles. Inflammation then may lead to the eruption of large pus-filled spots characteristic of acne. Acne tends to occur on the face, upper arms, upper back and chest.

In general doctors tend to dismiss the possibility of a causal link between the diet and the incidence of acne. However, a large body of scientific evidence now supports such a link. A recent review published in the US journal Seminars in Cutaneous Medicine and Surgery linked diet (either directly or indirectly) to these principal causes of acne (Cordain, 2005). Further to this, a study of 47 acne patients confirmed a causal link between diet and acne. Results suggest that refined grains, sugars, potatoes, processed foods, milk, yogurt and ice-cream together with diets characterised by a high omega-6 to omega-3 fatty acid ratio underlie the development of acne. In these dietary intervention tests all dairy foods, virtually all processed foods, refined grains and sugar were eliminated from the diet which was then comprised primarily of lean meats, fish, fresh fruits and vegetables. Subjects who followed this diet showed immediate improvement in symptoms and eventually became completely clear of acne. The results of this year long experiment will be published in a series of papers in the next year (Cordain, 2005a).

A report linking teenage acne directly to the consumption of dairy foods was published in the Journal of the American Academy of Dermatology in 2005 (Adebamowo, 2005). A link between the intake of milk during adolescence and the incidence of acne was observed in 47,355 women who completed questionnaires on high school diet and teenage acne (as diagnosed by a doctor). Because the link between teenage acne and milk consumption was strongest for skimmed milk, it would seem that the saturated fat content of milk is not the causal factor. The authors hypothesise that the hormonal content of milk may be responsible for causing acne in teenagers. Cow’s milk contains the hormones oestrogen and progesterone along with certain hormone precursors (androstenedione, dehydroepiandrosterone-sulphate, and 5ª-reduced steroids like 5ª-androstanedione, 5ª-pregnanedione and dihydrotestosterone), some of which have been implicated in the development of acne. The levels of these hormones in cow’s milk vary depending on whether the cow is pregnant or not, and if so at what stage of the pregnancy she is. At least two-thirds of cow’s milk in the UK is taken from pregnant cows (Danby, 2005).

Milk also contains bioactive molecules that act on the sebaceous glands and hair follicles (such as glucocorticoids, IGF-1, transforming growth factor-ß (TGF-ß), neutral thyrotropin-releasing hormone-like peptides, and opiate-like compounds), some of which survive pasteurisation. The bioavailability of the factors involved may be altered during pasteurisation. In other words, heat-induced changes in the shape or structure of the molecule may alter the way it behaves in the body and, until we know more, it is difficult to say exactly what role these bioactive molecules play in causing acne and other health problems.