Effects of nutrition on metabolic and endocrine outcomes in women with polycystic ovary syndrome: an umbrella review of meta-analyses of randomized controlled trials.

This umbrella review summarizes evidence from 28 meta-analyses of randomized clinical trials on the effects of nutritional interventions in adult women with polycystic ovary syndrome (PCOS). Dietary modifications—including lower-carbohydrate diets (LCD), the Dietary Approaches to Stop Hypertension (DASH) diet, and lower glycemic index/load (GI/GL) diets—showed some favorable effects on weight, fasting insulin (FI), fasting plasma glucose (FPG), and lipid profiles, but the certainty of this evidence was very low to low. Supplementation with vitamin D, probiotics/synbiotics, omega-3 fatty acids, inositol (including myo-inositol and D-chiro-inositol), and curcumin demonstrated moderate to high certainty evidence for improving metabolic outcomes such as FI, insulin resistance (measured by HOMA-IR), and triglycerides; probiotics/synbiotics also possibly reduce total testosterone, and inositol may increase ovulation rates in subfertile women with PCOS. However, no high-certainty evidence supports diets alone for improving reproductive outcomes, and effects on inflammation, oxidative stress, and long-term clinical endpoints remain uncertain.