Hypovitaminosis D in healthy children in Central Thailand: prevalence and risk factors

Abstract

BackgroundThere are limited data regarding the prevalence and risk factors relating to hypovitaminosis D in children of Thailand, a tropical country with abundant sunlight. The objective of this study was to assess the prevalence of hypovitaminosis D and examine factors associated with hypovitaminosis D in school-aged children in Bangkok, Thailand – a centrally located capital city.MethodsThis cross-sectional study evaluated 159 healthy children (33.3% boys and 66.7% girls), aged 6 to 12 years, in Bangkok, Thailand (located at 13.45°N). Fasting plasma samples were examined for total 25-hydroxyvitamin D [25(OH)D] using electrochemiluminescence immunoassay. Demographic characteristics (age, sex, household income), past medical history (birth weight, allergic diseases, hospitalization), amount of sun exposure, anthropometric data, and selected biochemical tests were used to investigate for factors associated with hypovitaminosis D.ResultsOverall, the mean ± SD level of plasma 25(OH)D was 64.0 ± 15.1 nmol/L. Hypovitaminosis D (< 75 nmol/L) was presented in 79.2% of subjects. Of these, the prevalence of vitamin D insufficiency and vitamin D deficiency were 59.7% and 19.5%, respectively. In univariate analysis, children with hypovitaminosis D (< 75 nmol/L) had a higher mean body mass index (BMI) percentile than the vitamin D-sufficient group (56.7 ± 33.9 vs. 42.6 ± 36.0; P-value = 0.04). Plasma PTH levels in the children with hypovitaminosis D were significantly higher than in the children with normal levels of vitamin D (4.34 ± 1.38 vs 3.78 ± 1.25 pmol/L; P-value = 0.04). In multivariate analysis, high BMI percentile and high PTH concentration were the parameters associated with 25(OH)D level < 75 nmol/L.ConclusionThe prevalence of hypovitaminosis D in healthy Thai children is very high, despite their exposure to sunlight, and that prevalence increases in children with a high BMI percentile. As a result, a formal recommendation for vitamin D supplementation in Thai children should be considered.

Vitamin D status is associated with underweight and stunting in children aged 6–36 months residing in the Ecuadorian Andes

“…Both conditions increase the solar UV radiation index (12) and are conducive to epidermal vitamin D synthesis (13) . However, previous studies in countries with low latitude (4,14,15) and/or high altitude (16)(17)(18) show that this does not necessarily translate into a low population prevalence of vitamin D deficiency.…”

Vitamin D status in perinatally HIV-infected Thai children receiving antiretroviral therapy

“…This could be from minimal variation of temperature, sunlight, and pollution between summer and rainy season in Thailand as well as most tropical countries. The study in healthy Thai children without HIV in Bangkok aged between 6 and 12 years reported vitamin D insufficiency (between 10 and 30 ng/mL) in 79% of cases; none had vitamin D level < 10 ng/mL (20). Meanwhile, another Thai study in an older population aged > 15 years reported vitamin insufficiency and deficiency in 65% and 14%, respectively (18).…”

Parental Encouragement of Healthy Lifestyles for Their Children and Personally Caring about Healthy Lifestyles Is Positively Associated with Children Using Vitamin D Supplements

“…Body mass index is negatively associated with vitamin D status [31,32,33,34,35] and vitamin D inadequacy is highly prevalent among children who are overweight or obese compared to non-overweight children [1]. Obese children may have elevated vitamin D requirements due to the sequestration of lipid-soluble vitamin D in a larger pool of adipose tissues [6,35,36], lower vitamin D metabolism in the liver [36], increased vitamin D catabolism in the kidneys [6,36], or limited sun exposure due to low physical activity levels [36]. The beneficial effect of healthy lifestyle practices on preventing excess body weight is widely reported [11,14,15].…”

“…Vitamin D sufficiency is associated with supplement use among Canadians [2,3,4,5,6] and studies worldwide [7,8] have suggested supplementation with vitamin D as a strategy to reduce poor vitamin D status. Despite the evidence that Canadians who use supplements are more likely to maintain adequate vitamin D levels [3,4], it has been estimated that 71% of grade 5 children in the province of Alberta do not take vitamin D supplements [9].…”