One of the most well studied supplements for PCOS is inositol. Some studies have found inositol can improve insulin resistance and fertility in PCOS, though the quality of the evidence is not especially high.[1][2] Other supplements investigated for PCOS include L-carnitine, omega-3 fatty acids (e.g., fish oil), alpha-lipoic acid, berberine, and N-Acetylcysteine.[3][4]