Hypovitaminosis D is a condition determined by serum concentrations of vitamin D [25 (OH) D] d 30 nmol / L. It's more prevalent in older individuals (e 50 years) due to the fact that aging is accompanied by reduced cutaneous synthesis of vitamin D and decreased expression of vitamin D receptors in tissues in general. Moreover, aging is also accompanied by changes in body composition such as decline in muscle mass and increased adiposity, which may also be associated with hypovitaminosis D. In this sense, recent findings suggests an inverse association between increased body fat and a decline in serum 25(OH)D concentrations, which indicates the possibility of abdominal obesity being a risk factor for lower serum concentrations of vitamin D. Objective: The present project aims to study the incidence of vitamin D insufficiency and deficiency in English individuals with and without abdominal obesity aged e 50 years. Methods: This is an incidence study covering a sample of 9.169 individuals aged e 50 years, participants from the English Longitudinal Study of Aging (ELSA). At the baseline, will be measured the waist circumference (WC), serum concentrations of 25(OH)D, sociodemographic status, behavioral characteristics and clinical conditions of participants. Abdominal obesity will be defined by WC > 88 cm for women and > 102 cm for men and serum concentrations of 25(OH)D will be classified as sufficient (> 50 nmol/L), insufficient (< 30 d 50 nmol/L) and deficient (d 30 nmol/L). Only individuals with 25(OH)D sufficiency will be included in the baseline. After four years of follow-up, the incidence of 25(OH)D deficiency and insufficiency in obese and non-obese abdominal individuals will be verified. Sociodemographic status, behavioral characteristics and clinical conditions will be considered as control variables in the multinomial regression models, to identify the factors associated with low serum vitamin D concentrations in obese and non-obese individuals. Expected results: The incidence of low serum vitamin D concentrations are expected to be higher in abdominal obese individuals.
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