Laboratory of Epidemiology and Biostatistics, National Institute of Gastroenterology, "S. de Bellis" Research Hospital, Castellana Grotte (Bari), Via Turi 27, 70013 Castellana Grotte, Italy. Department of Clinical Pathology, National Institute of Gastroenterology, "S. de Bellis" Research Hospital, Castellana Grotte (Bari), Via Turi 27, 70013 Castellana Grotte, Italy. Scientific and Ethical Committee, University Hospital Policlinico, 70124 Bari, Italy. Ambulatory of Clinical Nutrition, National Institute of Gastroenterology, "S. de Bellis" Research Hospital, Castellana Grotte (Bari), Via Turi 27, 70013 Castellana Grotte, Italy.