Dr Perricone's ideas about sugar and ageing have gained much credence in the scientific community. But many of his most devout followers do not realise the findings' implications for acne sufferers.

While eating refined carbohydrates will not necessarily cause acne, what is becoming increasingly indisputable is that such foods can produce acne in susceptible individuals, such as adolescents, or aggravate acne in anyone already suffering from the condition.

A 2002 study by Loren Cordain, a professor at the University of Colorado, compared the eating habits of the Kitvian islanders of Papua New Guinea and the Ache hunter-gatherers of Paraguay. These groups were chosen because they were the least influenced by increasingly widespread westernised diets. The result: they had no incidence of acne.

These population groups were geographically and ethnically unrelated. The non-incidence of acne seemed less attributable to their genes but more to environmental factors.

Dr Cordain concluded that those high-glycaemic foods that we increasingly eat today 'contribute to the acne suffered by 95 per cent of westernised teenagers'.

The report shook the long-held belief among dermatologists that there was no linkage between diet and acne.

Scientists attributed their results to a biochemical chain of events. The theory is that our modern, high-glycaemic diet permanently raises the body's insulin levels, which elevate other hormones and growth factors. These chemicals stimulate the skin to overproduce sebum, or oil, clogging pores and producing a playground for bacteria - and acne.

Acne sufferers themselves remain perplexed by their own condition.

Andrew John Otremba, 19, who studies mechanical engineering at the University of Nottingham, has been visiting a dermatologist for the past year because of an acne condition. He has been taking light doses of antibiotics.

'The condition is suppressed when I am on [antibiotics], and when I stop taking them it starts again,' he said.

'Sometimes, I still get a couple of pimples even when I am on medication, but certainly less seriously than when I am not.'

He did not believe his diet caused his acne, although he admitted that his diet consisted mostly of meat.

'I have a friend who also has acne problems, and she eats a lot of vegetables,' he said. His personal experience seems to point to the weather.

His acne gets worse when he visits friends and family in Bangkok and Hong Kong.

'When I live in Britain I don't have an acne problem. It's only when I am in Hong Kong or Bangkok that my acne starts. My dermatologist said it may be the humidity that aggravates my skin,' he said.

He believed his condition was a classic case of teenagers going through changes in their bodies and that the problem would eventually go away.

'I have known a lot of people who had acne when they were teenagers and in their adult years the acne just faded,' he said.

He believed that there was no one cure for all, and that everyone would need to find something that worked for them.

Mr Otremba's conclusion is consistent with that of Zoe Diana Draelos, clinical associate professor of dermatology at Wake Forest University School of Medicine, North Carolina. She told a dermatology industry publication that she had treated patients who noted dietary connections, but each would talk of a different food.

'The most commonly mentioned connection is between soft drinks and acne. I personally believe that acne is related to hormonal changes, which ultimately influences sebum production that is essential to adolescent acne,' she said.

'I think there are many diseases called 'acne', but the etiology of each disease is different. Adolescent acne is clearly different from acne in women aged 40 to 50.'