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 between the ages of 11 and 30 will be affected by acne. It is most common between the ages of 14 and 17 in girls, and between 16 and 19 in boys. Acne can continue into adult life; about five per cent of women and one per cent of men have acne over the age of 25 (NHS Choices, 2012a).
Acne can cause physical scarring but it can also cause distress, anxiety 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. Despite the wholesale dismissal of diet as a potential environmental factor underlying the development of acne, a large body of evidence now exists that demonstrates how certain foods and food substances (especially cow’s milk) may adversely influence hormones and cytokines that influence the causes of acne (Cordain, 2005).
A large-scale study from Harvard’s School of Public Health linked the intake of milk during adolescence with the incidence of acne in 47,355 nurses who completed questionnaires on high school diet and teenage acne (Adebamowo et al., 2005). The link between teenage acne and milk consumption was strongest for skimmed milk, so it would seem that the saturated fat content of milk is not the causal factor. The authors hypothesised 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). The same team of researchers have produced two subsequent articles based on the nurses’ sons and daughters. In these groups too, a positive association was observed between dairy products (particularly skimmed milk) and acne (Adebamowo et al., 2006; Adebamowo et al., 2008). Again, this suggests that it is some component in cow’s milk other than saturated fat that causes acne.
Body builders who use steroid hormones to stimulate muscle growth and strength are more prone to acne as many of the side effects of steroids are manifested in the skin. This also applies to athletes who use whey-based supplements for weight gain as these protein powders increase IGF-1 and insulin levels, both of which are linked to acne. A number of recent studies have revealed a link between whey protein and acne. One case study showed that healthy male adults developed acne after the consumption of whey protein (Simonart, 2012). Another found that benzoyl peroxide cream or oral antibiotics had little effect on treating the serious acne affecting five young men who used whey supplements. However, when they stopped using whey, their acne became less severe and was treatable (Silverberg, 2012). The author of this study recommends that use of whey protein supplements should be screened for when taking history from teenage males suffering with acne.
Milk also contains many bioactive molecules that act on the sebaceous glands and hair follicles (such as glucocorticoids, IGF-1, transforming growth factor-β (TGF-β), 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. However, the current literature leaves no room for doubt that dairy products increase the risk of acne. In summary, to help eliminate or avoid acne, eat more fruit and vegetables and stay away from cow’s milk and dairy products.