Increases in summer serum 25-hydroxyvitamin D (25OHD) concentrations in elderly subjects in São Paulo, Brazil vary with age, gender and ethnicity

Abstract

BackgroundHypovitaminosis D is a common condition among elderly individuals in temperate-climate countries, with a clear seasonal variation on 25 hydroxyvitamin D levels, increasing after summer and decreasing after winter, but there are few data from sunny countries such as Brazil. Many factors can interfere on vitamin D cutaneous synthesis. We aimed at studying the 25OHD variations during winter and summer in an outdoor physically active elderly population living in São Paulo city, and analysed their determining factors.MethodsNinety-nine individuals (52 women and 47 men, from 55 to 83 years old) from different ethnic groups were selected from an outdoor physical activity group. Data are reported as Mean ± SD, and we used Pearson Linear Correlation, Student's t-test for non-related samples, Chi-square (χ²) test and One-way ANOVA for analysis.ResultsMean 25OHD value for the whole group was 78.9 ± 30.9 nmol/L in the winter and 91.6 ± 31.7 nmol/L in the summer (p = 0.005). Mean winter serum 25OHD concentrations were not different between men and women (81.2 ± 30.1 nmol/L vs. 76.7 ± 31.8 nmol/L, respectively), and 19.2% of the individuals showed values < 50 nmol/L. In the summer, we noticed an increase only for men (107.6 ± 31.4 nmol/L) compared to women (76.7 ± 24.0 nmol/L), and 6.5% showed values < 50 nmol/L. A decrease in the mean PTH in the summer compared to the winter was noticed, with PTH levels showing a relationship with 25OHD concentrations only in the winter (r = -0.208, p = 0.041). White individuals showed an increase in mean serum 25OHD in the summer (p = 0.016) which was not noticed for other ethnic groups (Asians, native Brazilians and blacks). An increase in 25OHD values in the summer was observed in the age groups ranging from 51-60 and 61-70 years old (p < 0.05), but not in the age group from 71 years old on.Conclusions25OHD values increased during the summer in elderly residents of São Paulo, but to different extents depending on ethnicity, gender and age. This season-dependent increase was noticed only among men, white and who were in the youngest group of individuals.

Impact of gender on vitamin D deficiency in morbidly obese patients: a cross-sectional study

“…A recent Norwegian study of both lean and morbidly obese persons also found that men had larger seasonal variation of vitamin D concentration than women, in particular young nonobese men (Lagunova et al, 2009). Similar findings have been reported from New Zealand and Brazil, where middle aged and older men had a larger reduction in 25(OH)D during the winter season than women (Bolland et al, 2007;Maeda et al, 2010).…”

Vitamin D deficiency in Spain: a population-based cohort study

“…On the other hand, the variability in iPTH with seasonal climate changes was lower than that for 25-hydroxyvitamin D, as occurred elsewhere (von Mühlen et al, 2005), and the correlation between iPTH and 25-hydroxyvitamin D was less obvious in spring and summer (data not shown), as in other studies (Maeda et al, 2010), probably related with the different turnover of vitamin D3 and iPTH at a time when the production of vitamin D3 in the skin is greater. In general, most studies assume that iPTH reaches a plateau when 25-hydroxyvitamin D values reach a particular concentration (Chapuy et al, 1997;Khosla et al, 1997;Malabanan et al, 1998;Thomas et al, 1998;Leboff et al, 1999;von Mühlen et al, 2005).…”

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

“…Ho wever, three studies involving adolescents showed high prevalence of hypovitaminosis D in this age group of the Brazilian population (6466). The factors that seem to favor the presence of higher serum concentrations in our population are: younger age (64,6769), commu nity life (70), the practice of outdoors physical activity (64,71), vitamin D oral supplementation (72), season of the year (spring, summer) (6873), residence in sun ny beach areas (74,75) and in lower latitudes (76). Current evidence does not support the concept of general population supplementation (41) (A).…”