MPO and endometriosis: In addition, even if a recent study by Santanam et al. showed that oral supplementation with Vitamin C and E lead to a significant decrease in FF myeloperoxidase (MPO) concentration in patients with severe endometriosis undergoing IVF [40], whether oral anti-oxidant therapy might have a beneficial effect on the quality of oocytes of endometriosis patients is still far from being proved.