Bread linked to teenage acne

Scientists in the United States believe the refined grain and sugar in some bread can cause high levels of insulin.

Previous studies have suggested that too much insulin can cause acne.

The finding appears to back up claims that low-carbohydrate diets can help to reduce acne in some people.

Loren Cordain and colleagues at Colorado State University have suggested that because refined bread is easy to digest it leads to a surge in insulin and an insulin-like growth factor called IGF-1.

Insulin link

This in turn leads to an excess of male hormones, which encourage the skin to excrete large amounts of sebum.

This grease-like substance encourages the growth of bacteria responsible for acne.

The scientists believe the modern Western diet is to blame.

Up to 60% of 12-year-olds and 95% of 18-year-olds suffer from acne.

But in a study to be published in the journal Archives of Dermatology, they point to a lack of acne among teenagers living in other parts of the world, where food is largely unprocessed.

They cite the examples of the Kitava Islanders in Papau New Guinea and the Ache of the Amazon, where acne is almost unknown.

"The only foods available to these populations are minimally processed foods," Ms Cordain told New Scientist magazine.

They also point to the experience of the Inuit people of Alaska. Acne only appeared when people there starting eating a Western diet.

Scientists in Australia are planning a major study to see if eating a low-carbohydrate diet can reduce the incidence of acne.

Researchers at the RMIT University in Melbourne are planning to test the theory on 60 teenage boys over three months.

It will be one of the first controlled studies to examine the effects of a low-carbohydrate diet on acne.

"There's a lot of anecdotal evidence," Neil Mann, one of the researchers told New Scientist magazine.

"Dermatologists will tell you they have put patients on low-carbohydrate diets and seen improvements. This will be the first controlled study."