To the Editor The finding by Armstrong et al1 that adolescent non–high-density lipoprotein cholesterol (HDL-C) shows the strongest association with the presence of coronary artery calcification in midadulthood is no doubt important. Their results add to the renewed effort to focus on early-life risk factors of cardiovascular diseases, but they ignore a potential confounding factor that might influence the association between non–HDL-C and coronary artery calcification. Extensive data have documented that not breastfeeding is associated with high concentrations of non–HDL-C in adolescents and consequently with the development of coronary artery disease in adulthood.