Effect of bariatric surgery on the prevalence of micronutrient deficiencies and protein status

BACKGROUND: Bariatric surgery (BS) is the most effective long-term therapy for the treatment of severe obesity. Benefits of BS include a reduction of overall and cardiovascular mortality, incidence of first occurrence of fatal- or nonfatal-cardiovascular events, prevention and remission of type 2 diabetes mellitus, and improved quality of life. Nonetheless, BS is associated with potential complications amongst which micronutrient deficiencies are relevant. AIM: Against this background, the overall aim of this PhD project was to better understand the increased risk for nutritional deficiencies and protein status in subjects undergoing BS. METHODS: We prospectively evaluated the nutritional status of obese individuals prior to BS, and following the drastic reduction of daily energy intake, anatomical changes, and massive weight loss associated with the two currently most commonly performed surgical techniques [gastric bypass (GBP) and sleeve gastrectomy (SG)]. Additionally, to gain insight specifically on how to address the high prevalence of vitamin D (VD) deficiency, we performed two open-label, prospective studies aiming at evaluating the efficacy and safety of achieving 25-hydroxy VD (25(OH)D) levels ≥75 nmol/L with two different supplementation algorithms. Similarly, we gained insight on the reported high prevalence of iron deficiency by characterizing iron status with the evaluation of indices of systemic inflammation. Finally, we performed two observational prospective studies to evaluate the effects of dietary protein intake (PI) on fat free mass (FFM, as assessed from bioelectrical impedance or DEXA) and protein status changes after BS-induced weight loss. As further step in this research path, a randomized control trial proposal has been designed to determine the effect of two levels of PI (standard versus high) after BS on the nitrogen balance, body composition, energy expenditure, perceived satiety, and plasma levels of branched chain amino acids (BCAA) and insulin sensitivity, as well as the feasibility of protein supplementation up to one year after BS. This translational research protocol integrates mechanistic, metabolic, and energy homeostasis outcomes. Preliminary results of a pilot study of that trial are presented as part of this thesis project to demonstrate feasibility of the protocol. RESULTS: Nutritional deficiencies are commonly found in a Mediterranean severely obese population undergoing BS, with those deficiencies being more preva