A scientific article published in “Nature Scientific Reports” reveals that the oxidation of the amino acid methionine is a blood marker that indicates the oxidation of good cholesterol. This oxidation prevents the cholesterol from maturing and, therefore, from carrying out its protective function. This study -carried out by CIBERDEM/URV researchers jointly with researchers from the Sant Joan de Déu Hospital- has been carried out in a group of girls in the initial stages of polycystic ovary syndrome, which can lead to a high risk of anovulatory infertility, type 2 diabetes, cardiovascular diseases and metabolic syndrome in adulthood.