Ketogenic diets may improve reproductive hormone levels in women with polycystic ovary syndrome (PCOS), new research suggests.
In the first-ever systematic review and meta-analysis of clinical trials on the association, ketogenic diets followed for 45 days to 24 weeks showed improvements in the luteinizing hormone (LH)/follicle-stimulating hormone (FSH) ratio, serum free testosterone, and serum sex hormone binding globulin (SHBG).
Previous evidence supporting ketogenic diets in PCOS has been “relatively patchy,” and although there have been reviews on the topic, this is the first meta-analysis, write Karniza Khalid, MD, of the National Institutes of Health, Ministry of Health Malaysia, and colleagues.
Study co-author Syed A.A. Rizvi, MD, PhD, told this news organization: “Our paper supports the positive effects of short-term ketogenic diets on hormonal imbalances commonly associated with PCOS, a complex disease state associated with a multitude of presenting symptoms among individuals. Based on the presentation and individual patient circumstances, besides pharmacologic treatment, lifestyle changes and a ketogenic diet can lead to even faster improvements.”
However, Dr. Rizvi, a professor at the College of Biomedical Sciences, Larkin University, Miami, cautioned: “I would highly recommend a keto diet to women suffering from PCOS, but we all know every person has a different situation. Some may not want to change their diet, some may not be able to afford it, and for some it is just too much work. ... This is why any lifestyle change has to be discussed and planned carefully between patients and their health care providers.”
The findings were published online in the Journal of the Endocrine Society.
The literature search yielded seven qualifying studies of ketogenic diets, generally defined as a daily carbohydrate intake below 50 g while allowing variable amounts of fat and protein. A total of 170 participants were enrolled in the studies from Italy, China, and the United States.
Pooled data showed a significant association between ketogenic diet and reduced LH/FSH ratio (P < .001) and free testosterone (P < .001). There was also a significant increase in circulating SHBG (P = .002).
On the other hand, serum progesterone levels did not change significantly (P = .353).
Weight loss, a secondary outcome, was significantly greater with the ketogenic diet (P < .001).
“Since low-carbohydrate diets have shown to be effective in addressing obesity and type 2 diabetes, it makes sense that they would also be helpful to the patients with PCOS, and in fact, it has been the case,” Dr. Rizvi noted.
The exact mechanisms for the hormonal effects aren’t clear, but one theory is that the reduction in hyperinsulinemia from the ketogenic diet decreases stimulation of ovarian androgen production and increases SHBG levels. Another is that the physiologic ketosis induced by low carbohydrate intake reduces both circulating insulin and insulin-like growth factor-1, thereby suppressing the stimulus on the production of both ovarian and adrenal androgens.
The analysis didn’t include pregnancy rates. However, Dr. Rizvi noted, “there have been published studies showing that [patients with] PCOS on keto diets have significantly improved pregnancy rates, also including via [in vitro fertilization].”
The study received no outside funding. The authors have reported no relevant financial relationships.
A version of this article appeared on Medscape.com.