The increased sebum secretion is caused by androgens, such as dihydrotestosterone, a by-product of testosterone metabolism. In teens the most common cause is a heightened secretion of DHEA, an adrenal androgen that peaks during teen years. Genetics also plays a role. And while acne is usually thought of as a teenage affliction, 54 percent of women and 40 percent of men over age 25 also have it. Acne is also a common side effect of anabolic steroids, which are synthetic versions of testosterone.
While most practicing dermatologists downplay the effects of diet on acne production, an interesting new study once again postulates that dietary factors promote the release of hormones linked to acne.1 The study, which was reported by advocates of a popular eating plan known as the Paleolithic diet, examined the prevalence of acne in two comparatively primitive populations, the Kitavan islanders of New Guinea and the hunter-gatherer Ache of Paraguay.
What those peoples have in common is a reliance on unprocessed foods—much in the manner of Stone Age, or Paleolithic, humans. They show no evidence of such degenerative conditions as cardiovascular disease, cancer and diabetes, which are commonplace in the industrialized West. They’re also more physically active and are almost never fat, and they show no signs of insulin resistance.
What the researchers found was that neither the Ache nor the Kitavan islanders showed any incidence of acne in any age group—including teens. According to the authors, that’s because of their Paleolithic-style diets, although genetics may also play some role. On the other hand, people with similar genetic backgrounds who have adopted westernized eating habits do have a higher incidence of acne.
The diets followed by these peoples consist primarily of low-glycemic-index carbs, which promote minimal insulin output, and the authors believe that explains the absence of acne. The theory is that eating low-glycemic-index carbs limits not only insulin release but also insulinlike growth factor 1 (IGF-1), which works with androgens in promoting excess sebum secretion. Insulin increases levels of active, or free, IGF-1 in the blood because it lowers the production of the primary binding protein of IGF-1, called IGFBP-3.
The combination of higher insulin and IGF-1 levels prevents the liver synthesis of sex-hormone-binding globulin (SHBG), which binds androgens in the blood. That results in increased blood levels of androgens, such as testosterone, which, when converted into dihydrotestosterone (DHT) through the action of the enzyme 5-alpha reductase, leads to acne.
Thus, the dietary connection involving acne features an increased flow of hormones promoted by high-glycemic-index carbs. Insulin is the primary initiator of that hormonal cascade, resulting in increased sebum production. The theory is plausible and is one more reason that the Paleo eating plan, which features low-glycemic-index carbs, moderate protein and good fats, such as omega-3s, may be the best diet for overall health and fitness.
1 Cordain, L.C., et al. (2002). Acne vulgaris: a disease of western civilization. Arch Dermatol. 138:1584-1590
©,2013 Jerry Brainum. Any reprinting in any type of media, including electronic and foreign is expressly prohibited.
