Determinantes dietéticos da massa óssea na vida adulta

Abstract

Throughout life, the quantity and quality of bone mineral mass are determined by genetic and environmental factors and also depend on previous experiences, such as nutritional status, food consumption, physical activity and hormone levels. In this sense, it is proposed that bone mass in advanced age has determinants in the initial development of life which may result in an increased risk of fracture and future osteoporosis. In this thesis, we worked with data from the 1993 Pelotas Cohort and investigated the effect of diet, through the consumption of dietary calcium, milk and nutrient patterns, created from nutrients that affect calcium absorption, named bone friendly (characterized by the consumption of oxalate, protein, calcium and sodium) and unfriendly pattern (characterized by consumption of caffeine and negatively charged vitamin D) (Article 1) and body mass index (BMI), fat mass index (FMI), lean mass index (LMI) and obesity (Article 2) from adolescence to early adulthood on bone mineral density (BMD) of the whole body, lumbar spine and right femur at 22 years of age. It was also evaluated the effect of body size at birth and growth in height and weight at different periods of childhood and adolescence on full body BMD in early adulthood (Article 3). In all articles BMD was obtained through dual-energy X-ray absorptiometry (DXA) and analyzes were stratified by sex. The first one consists of a longitudinal analysis with the follow-ups performed at 18 and 22 years of age and it obtained a sample of 3,109 individuals. Regarding the consumption of milk between the follow-ups, we observed a negative effect for males, in the categories of increase and decrease of consumption with BMD of whole body and BMD of the femur. For the calcium intake, a positive association was observed for the female, in the category of increased consumption and BMD of the whole body. In the analysis of nutrient patterns, men with moderate or decreased adherence to the unfriendly pattern had an increase in the BMD of the whole body and women who also had a decreased consumption had an increase in lumbar spine BMD. The second longitudinal article was also performed with the follow-ups at 18 and 22 years of age, with a final sample of 2,968 participants. A positive association of the three indices on bone outcomes was observed, but with a higher magnitude for BMI, followed by LMI, suggesting that most of the positive effect of body mass on bone is due to the amount of lean mass. The last article, about conditional growth and BMD of the whole body, had data from follow-ups performed at birth, 1, 4, 11, 15 and 18, with a bone outcome measured at 22 years of age, totaling 756 individuals. The effects of weight gain and length/height were examined using conditional relative weight (CWh) and conditional length/height (CH). For men, greater height gain at 4, 11 and 18 years was associated with greater BMD of the whole body after adjusted analysis, being the result with greater magnitude the one at 11 years. For women, BMD was associated with height gain in all assessments up to 15 years, with the greatest measure of effect at 4 years. Regarding body weight, for males, greater birth weight and gain at 4, 15 and 18 years had a higher BMD, with higher coefficients at 18 years. For women, except for birth weight, all variables of weight gain were associated with the highest BMD, with higher coefficients observed for the 4 years.