Monday, November 9, 2009

Does chocolate give you zits?

Well, your Mum always reckoned it did when you were a teenager. That’s only because she loved you and thought it was helpful advice, not because she had read all the science on the topic. But, then again, there wasn’t much science on the link between food and acne anyway.

A lot of the research conducted last century wasn’t really high quality and led to the scientific view that what you ate probably didn’t make any difference to pimple production. A 1997 review article in the New England Journal of Medicine on the treatment of acne states: “Physicians should dispel the myth that diet or failure to cleanse the skin is responsible for acne.”

Case closed. And then reopened

When subscriber Mel asked if there was a link between chocolate and pimples, the answer would have been easy last century: No, Mel, there isn’t. The research on chocolate and other foods had shown no link between it and pimples. The case was closed. Then the case had to be re-opened again as a new theory emerged. Before I tell you about that, first what is acne?

What is acne?

Acne is an abnormality within the sebaceous glands associated with hair follicles on the face, back and chest. The whole process of acne begins at the age of 7-10 years, when hormonal surges cause the sebaceous glands to enlarge. Acne usually becomes visible in puberty, initiated by an increase in androgen hormones, especially dehydroepiandrosterone sulphate (DHEAS). The sebaceous glands secrete sebum that naturally flows to the surface of the skin. Should this flow be blocked by a plug (called a comedo), the oily sebum accumulates, and bacteria (Propionibacterium acnes) feed on the fats in the sebum and accumulate to eventually reach levels that form a pimple. (OK, close your eyes and repeat that back to me).

Not one food, but the diet as a whole

In 2002, a theory was proposed that, as non-westernised societies have almost no acne, a diet of high Glycaemic Index (GI) foods might influence the formation of pimples. Those carbohydrate foods that are quickly digested (ie high GI foods) may trigger high levels of insulin in the blood, elevating Insulin-like Growth Factor 1 (IGF-1), which in turn stimulates sebum production.

Subsequent published research tends to give this theory some credibility. A pilot study at the Royal Melbourne Institute of Technology, Australia on a small group of male teenagers confirmed that a high GI diet influenced hormones to promote acne development. This is still only a theory and more research needs to be done before any conclusions on GI and acne can be made.

As chocolate has a low to moderate GI (and has a moderate insulin response), this theory may not be relevant to chocolate consumption anyway. So, the answer to the original question remains: No, Mel, there isn’t.

What does it all mean?

Although we have a lot more to learn about pimples and diet, it seems safe to say that no single food causes acne; it is more likely to be the effect of the overall diet. As a general rule of thumb, the better the quality of the diet, the lower the GI and the less likelihood of getting a zit. Choosing highly processed foods tends to lead to higher blood glucose levels, higher insulin, changes in hormonal levels and a greater chance of waking up with a huge zit in the middle of your forehead.

Reference: Mol Nutr & Food Research 2008; 52 (6): 718-726

1 comment:

Unknown said...

Thanks, Glenn - you've reassured this chocaholic!

Seriously, though, I appreciate you sifting through the research and presenting it in a way even I could understand.