Low-fat Low-Sugar Diet Puts Acne-Marked Faces in the Clear

MELBOURNE, Australia, Aug. 23 -- Adolescent boys deprived of a high glycemic index junk-food diet had better clearing of acne vulgaris in 12 weeks than a medicine chest full of pimple medications can provide.

Young men with mild-to-moderate facial acne who were randomly assigned to eat an experimental low glycemic load diet had significantly fewer lesions after three months than their peers who followed a more typical teen diet, reported Robyn Smith, Ph.D., of the RMIT University School of Applied Sciences here, and colleagues.

The low glycemic load diet was also associated with weight loss, a reduction in circulating free androgen, and an increase in insulin-like growth factor binding protein-1 compared with the high glycemic load diet, the investigators reported in the August issue of the Journal of the American Academy of Dermatology.

"The acne of the boys on the higher protein, low glycemic index diet improved dramatically, by more than 50%, which is more than what you see with topical acne solutions," said senior author Neil Mann, Ph.D.

"A diet high in processed foods pushes glucose and insulin levels higher, exacerbating the problem, but low glycemic foods do the opposite. The mechanism and the results are as clear as day," he said.

The findings could explain why acne, the scourge of adolescents in industrialized nations, is uncommon in the developing world, the authors said.

In their study, results of which were first presented at a European dermatology meeting in 2006, the authors enrolled 50 teens and young men, ranging in age from 15 to 25, in a 12-week, parallel, dietary intervention study.

The participants assigned to eat the low glycemic load diet were taught how to substitute high glycemic index foods with those high in protein, such as lean meats, poultry, or fish, balanced with other low glycemic index foods such as whole grain bread, pasta, and fruits. Some of the food was supplied, and the participants were urged to eat them daily.

The recommended diet was composed of 25% energy from protein, 45% from low glycemic index carbohydrates, and 30% energy from fats.

"In contrast, the control group received carbohydrate-dense staples and were instructed to eat these or similar foods daily," the authors wrote. "The foods provided had moderate to high glycemic index values and were typical of their normal diet as evidenced from seven-day weighed/measured food records."

All participants were instructed in the use of food scales and how to keep food records. The investigators monitored dietary compliance with regular telephone interviews, assessments of glycemic load per day and 24-hour urine samples at baseline and at 12 weeks for assessment of urea excretion relative to urinary creatinine.

All participants were also provided with a mild facial cleanser, which contained no anti-acne ingredients, and began using it two weeks before they started the diet and throughout the study.

The study endpoints were the effects of the relative diets on acne vulgaris, (determined by changes in lesion count by investigator-masked dermatology assessments) and on endocrine aspects of the condition, including sex hormone binding globulin, free androgen index, insulin-like growth factor-I, and insulin-like growth factor binding proteins.

The authors found that at the end of the study, the decrease in total lesion counts in the low glycemic load diet group was significantly greater than among controls, at -21.9 (95% confidence interval, -26.8 to -9.0) versus -3.8 (95% CI, -19.1 to -8.5, P=0.01).

In addition, volunteers on the experimental diet had significantly greater weight loss (P