PCOS affects between five and ten per cent of all women of childbearing age and is a leading cause of infertility, according to the US National Women's Health Information Center. While the direct cause is not known, the condition is strongly associated with insulin resistance.
European Society of Human Reproduction and Embryology (ESHRE) define the condition as having irregular ovulation, increased levels of the make hormone androgen, and the presence of cysts on the ovaries.
The researchers, led by Crystal Douglas from the University of Alabama at Birmingham, hypothesized that a low-carbohydrate diet could increase insulin sensitivity, and decrease circulating insulin levels, which in turn decreases levels of insulin-stimulated androgen synthesis.
Eleven non-diabetic women with clinically diagnosed PCOS were recruited to take part in three 16-day trials. The women consumed three test diets with three-week washout periods between each diet intervention period. The average age of the women was 33, with an average BMI of 30 kilograms per square metre.
The effects of the low-carbohydrate or a monounsaturated fatty acid (MUFA)-enriched diet were compared to a standard diet containing 56 per cent carb, 16 per cent protein, 31 per cent fat. The fatty acid content of the standard diet was 10 per cent polyunsaturated fatty acids (PUFA) and 13 per cent MUFA.
The low-card diet consisted of 43 per cent carb, 15 per cent protein, 45 per cent fat. PUFAs made up 17 per cent, while MUFAs 18 per cent. The MUFA-enriched diet consisted of 55 per cent carb, 15 per cent protein, 33 per cent fat. PUFAs made up 6 per cent, while MUFAs 17 per cent. All diets were equally calorific.
The low-carb diet "significantly affected concentrations of fasting insulin, cholesterol, free fatty acids, and acute insulin response to glucose, but circulating concentrations of the reproductive hormones were not significantly affected by the intervention," wrote the authors in the journal Fertility and Sterility (Vol. 85, pp. 679-688).
From baseline values, levels of fasting insulin decreased by 31 per cent, and the acute insulin response to glucose decreased by 16 per cent for the low-carb diet. The MUFA-enriched diet decreased levels of insulin by 25 per cent, and the acute insulin response to glucose level actually increased by seven per cent.
"Because elevated insulin is thought to contribute to the endocrine abnormalities in PCOS, a reduction in insulin would be expected to ultimately result in an improved endocrine profile.
Utilising this low carbohydrate diet in conjunction with a reduced calorie, weight loss regimen may produce additional favourable results in overweight and obese PCOS subjects," concluded the researchers.
The low carb diet boom looks over for people in the mainstream, with Atkins Nutritionals, one of the main proponents of the low carb lifestyle, filing for bankruptcy last year. However, a recent meeting of scientists discussed the 'Nutritional and Metabolic Aspects of Carbohydrate Restriction'.
The advocates who attended the conference were more interested in low carb from a disease management viewpoint rather than a general approach to nutrition.
Indeed, conference organizer Richard Feinman, professor of biochemistry at SUNY Downstate Medical Center in Brooklyn said in January: "Some of the clinical results, particularly in diabetes, are quite remarkable."