Background: Endothelial dysfunction is the first stage of atherosclerosis, this has been associated with changes in the lifestyle of our population as is the consumption of processed foods rich in carbohydrates and saturated fats. Objective: To evaluate the effect on endothelial function of donuts and milk industrialized in young medical students from the Universidad Michoacana de San Nicolás de Hidalgo. Patients and method: We included 31 young volunteers from the Medicine School of Universidad Michoacana de San Nicolás de Hidalgo in a transversal and prospective study, 17 women and 14 men, aged 21.6 ± 1.8 years, with a mean weight of 18.0 ± 70.2 kg and height of 1.6 ± 0.08 m were assessed. Subjects underwent clinical evaluation of endothelial function before and after 2 and 4 hours of eating four donuts and 250 ml of processed milk. The evaluation measured the diastolic blood pressure (DBP) in the radial artery with a semiautomatic Omron Hem-601, a control measurement of baseline and at 2, 5 and 7 minutes after arterial occlusion and flow-dependent dilation of the brachial artery. We assessed concentrations of triglycerides and glucose (glucose) levels of fasting and at 2 and 4 h after breakfast experimental. Results: There was a decrease in endothelial function at two and especially at 4 hours of eating breakfast. The glucose and triglycerides concentrations were stable in blood at fasting and 2 and 4 hours after breakfast, without reaching hypertriglyceridemia or hyperglycemia. Conclusions: The consumption of industrial milk and donuts for breakfast causes a decrease in endothelial function the first step of atherosclerosis, without any significant elevation in the levels of glucose and triglycerides, suggesting that other component, probably the type of fat of these foods leads to endothelial dysfunction. [ABSTRACT FROM AUTHOR]