RESUMEN
Recent data have revealed an inverse relationship between insulin resistance, which is associated with fatty liver disease, and blood 25-hydroxy-vitamin D (25(OH)D) levels. The aim of the present study was to determine the association of vitamin D levels with the presence and stage of fatty liver disease among non-obese subjects and to determine the effect of vitamin D status on fatty liver disease development. A total of 613 non-obese (body mass index <30 kg/m(2)) gastroenterology and internal medicine outpatients (472 women and 141 men) were enrolled in the study. The patients' laboratory values, including liver function tests, lipid profiles, C-reactive protein, fasting blood glucose, insulin, calcium and 25(OH)D levels were studied. Low vitamin D levels, higher triglyceride levels and higher alanine aminotransferase levels were found to be the significant determinants for non-alcoholic fatty liver disease. When the patients were evaluated as low or normal vitamin D groups, low vitamin D levels was determined to be a risk factor for fatty liver disease, with an odds ratio of -1.59 (confidence interval -1.22 to -1.97). The increased risk for fatty liver disease among patients with low vitamin D status may be suggestive of mechanisms promoting fat flow and accumulation in the liver. Molecular studies are warranted to elucidate the action of vitamin D on the liver with respect to fat metabolism.