Body fat and cholecalciferol supplementation in elderly homebound individuals

Abstract

Vitamin D deficiency, observed mainly in the geriatric population, is responsible for loss of bone mass and increased risk of bone fractures. Currently, recommended doses of cholecalciferol are advised, but since there are few studies evaluating the factors that influence the serum levels of 25-hydroxyvitamin D (25(OH)D) following supplementation, we analyzed the relationship between the increase in serum 25(OH)D after supplementation and body fat. We studied a group of 42 homebound elderly subjects over 65 years old (31 women) in order to assess whether there is a need for adjustment of the doses of cholecalciferol administered to this group according to their adipose mass. Baseline measurements of 25(OH)D, intact parathyroid hormone and bone remodeling markers (osteocalcin and carboxy-terminal fraction of type 1 collagen) were performed. Percent body fat was measured by dual-energy X-ray absorptiometry. The patients were divided into three groups according to their percent body fat index and were treated with cholecalciferol, 7,000 IU a week, for 12 weeks. The increases in serum levels of 25(OH)D were similar for all groups, averaging 7.46 ng/mL (P < 0.05). It is noteworthy that this increase only shifted these patients from the insufficiency category to hypovitaminosis. Peak levels of 25(OH)D were attained after only 6 weeks of treatment. This study demonstrated that adipose tissue mass does not influence the elevation of 25(OH)D levels following vitamin D supplementation, suggesting that there is no need to adjust vitamin D dose according to body fat in elderly homebound individuals.

Modifiable factors of vitamin D status among a Brazilian osteoporotic population attended a public outpatient clinic

“…Other authors have also observed lower 25(OH)D concentrations in smokers (10,42). Although a negative correlation between the 25(OH)D concentration and obesity has been observed by various authors (5,8,43), this result was not produced in our study and others (44). The majority of the participants had BMI between 18.5 and 29.9 kg/m 2 (median 25.6 kg/m 2 ), whereas only 13.5% had BMI ≥ 30 kg/m 2 .…”

“…The majority of the participants had BMI between 18.5 and 29.9 kg/m 2 (median 25.6 kg/m 2 ), whereas only 13.5% had BMI ≥ 30 kg/m 2 . In our study, this relative homogeneity of the population and the small number of participants with extreme weight values (BMI < 18.5 kg/m 2 and ≥ 30 kg/m 2 ) might have contributed to the lack of a relationship between the 25(OH)D concentration and obesity (44).…”

“…Cholecalciferol is fat-soluble and stored in body fat depots. As physical activity promotes weight loss, the stored cholecalciferol may be released, which leads to an increased 25(OH)D concentration (44). Exercise increases energy expenditure and activates thermogenic function in adipose tissues.…”

Recomendações da Sociedade Brasileira de Endocrinologia e Metabologia (SBEM) para o diagnóstico e tratamento da hipovitaminose D

“…However, to reduce fractures, concentrations above 24 ng/mL are necessary (86), while to avoid the development of secondary hyperparathyroidism, concentrations above 30 ng/mL are desirable (69). Therefore, especially during osteoporosis treatment, it In a study developed in Brazil, with an institutiona lized population, showing high prevalence of hypo vitaminosis D (40.4% with 25(OH)D < 20 ng/mL), supplementation with 7,000 IU/day, produced an average elevation of 7.5 ng/mL in 25(OH)D con centration after three months (87) and this elevation achieved a plateau around six weeks. However, as it has already been recognized by other authors, this in crease was more evident among those individuals with lower initial values (< 20 ng/mL), in whom the ave rage increase was 10.3 ng/mL after three months of treatment, while those showing 25(OH)D concentra tion above 20 ng/mL, increased on average only 5.18 ng/mL.…”

Vitamin D and obesity: current perspectives and future directions

“…However, given the decreased bioavailability of vitamin D in obesity, and the purported effect of volumetric dilution discussed earlier (26,31) , it is reasonable to assume that the typical response to supplementation may be different in overweight/obese individuals, albeit that they are usually starting from a lower baseline value. Table 1 shows nine studies, which have tested the hypothesis that adiposity can attenuate the 25(OH)D response to cholecalciferol supplementation (41,(99)(100)(101)(102)(103)(104)(105)(106) . In the majority of these studies, a significant inverse relationship was apparent between BMI and/or FM, and this occurred irrespective of population group and across a wide range of supplemental doses of cholecalciferol given for varying durations (1 week to 1 year) (41,99,101,(103)(104)(105)(106) .…”