Journal of the American Academy of Dermatology (57: 247-56)

Study

The effect of a higher protein, low glycaemic load diet vs a conventional, high glycaemic load diet on biochemical parameters associated with acne vulgaris. A randomised, investigator-masked, controlled trial.

Publication

Journal of the American Academy of Dermatology (57: 247-56)

Authors

Smith R, Mann N, Braue A, Makalainen H and Varigos G.

Background

The belief that the diet-acne link is a myth is based on two poorly controlled studies published over 30 years ago.

Acne prevalence varies substantially between populations and is low in traditional societies where the diet is based on fresh fruit, vegetables, lean meats and wholegrains. However when they adopt a more modern diet of processed foods, they also develop acne.

A unifying feature of traditional diets is low glycaemic load.

Objective

To compare the effect of a higher protein, low glycaemic load diet with a habitual high glycaemic load diet on the severity of acne symptoms and endocrine variables associated with insulin resistance.

Subjects

43 adolescent boys (aged 15-25 years) with acne.

Study design

Dietary intervention
Subjects were randomly assigned to one of two diets for twelve weeks:

Control group (CO; n=20) – Continued to eat their normal diet consisting of highly processed and refined foods.
Higher protein, low glycaemic load diet (HP–LGL; n=23) – Mirrored hunter-gatherer diet, including more natural foods, such as fresh fruit, vegetables, lean meats and wholegrains. Educated on how to substitute high GI foods with foods higher in protein or lower in GI.

All subjects used a low level topical acne facial wash.

Dermatological measurements
All acne lesions were located, counted and graded by size and severity every four weeks by a dermatologist masked to the subjects’ diet group.

Biochemical measurements
At baseline and at twelve weeks the following biochemical markers were measured:

Insulin resistance marker – homeostasis model assessment of insulin resistance (HOMA-IR).
Hormonal markers – testosterone, precursor to testosterone (dehydroepiandrosterone sulphate (DHEA-S), free androgen index (FAI), sex hormone binding globulin (SHBG).
Growth factors – insulin-like growth factor (IGF-1) and insulin-like growth factor-binding proteins -1& -3.

Results

Key finding – a higher protein, low glycaemic load diet comprising moderately high levels of protein and low GI foods produced significantly greater improvements in facial acne when compared with a high glycaemic load diet.
Dermatological measurements – although both groups showed improvement, the HP–LGL group showed a significantly greater reduction in the total number of acne lesions and inflammatory counts (51 per cent vs 31 per cent) after twelve weeks.
Biochemical measurements – the HP–LGL group also showed a reduction in: insulin resistance (HOMA-IR), hormonal markers of acne (FAI) and growth factors (IGF-1 activity) when compared with participants on a high glycaemic load diet.
The HP–LGL group also experienced a more significant change than the control group in body mass index, body fat percentage, waist circumference, blood lipids and weight loss, despite constant dietary counselling to maintain weight.

Conclusion

A higher protein, low glycaemic load diet helped to reduce insulin levels, which helped to control hormonal imbalances associated with acne. This resulted in a reduction in facial acne by more than 50 per cent. This is the first study to show that diet and acne are linked.

Link

Meat & Livestock Australia acknowledges the matching funds provided by the Australian Government to support the research and development detailed in this information.