Determinants of serum 25-hydroxyvitamin D in Hong Kong

Abstract

Vitamin D plays an important role in skeletal health throughout life. Some studies have hypothesised that vitamin D may reduce the risk of other diseases. Our study aimed to estimate age-specific and sex-specific serum 25-hydroxyvitamin D (25(OH)D) status and to identify the determinants of serum 25(OH)D status in Hong Kong, a subtropical city in southern China. In 2009 -2010, households in Hong Kong were followed up to identify acute respiratory illnesses, and sera from 2694 subjects were collected in three to four different study phases to permit measurement of 25(OH)D levels at different times of the year. A questionnaire survey on diet and lifestyle was conducted among children, with simultaneous serum collection in April and May 2010. The mean of serum 25(OH)D levels in age groups ranged from 39 to 63 nmol/l throughout the year with the mean values in all age groups in spring below 50 nmol/l. Children aged 6 -17 years, and girls and women had significantly lower serum 25(OH)D levels than adults, and boys and men, respectively (all P, 0·001). We estimated that serum 25(OH)D levels in Hong Kong followed a lagged pattern relative to climatic season by 5 weeks with lowest observed levels in early spring (March). For children aged 6-17 years, reporting a suntan, having at least 1 servings of fish/week and having at least 1 serving of eggs/week were independently associated with higher serum 25(OH)D levels. Adequate sunlight exposure and increased intake of dietary vitamin D could improve vitamin D status, especially for children and females in the winter and spring.

Weekday sunlight exposure, but not vitamin D intake, influences the association between vitamin D receptor genotype and circulating concentration 25‐hydroxyvitamin D in a pan‐European population: the Food4Me study

“…However, over the age of 70 years, 25(OH)D concentrations decrease due to impaired skin photosynthesis and renal conversion to the active form . We observed that circulating 25(OH)D concentrations were lower in females than males, which confirms previous findings among adults and children . A proposed explanation for this is that women are more diligent in applying sunscreen and in covering skin for social reasons and that men spend more time outdoors during physical activity and in manual occupations.…”

The association between serum 25‐hydroxyvitamin D levels and dental caries in US adults

“…Although studies have identified a similar association between serum 25(OH)D levels and dental caries in both children and adults, whether dental caries is associated with low serum levels of 25(OH)D remains unclear. In children, dietary patterns positively influence serum 25(OH)D concentrations (Xu et al., 2015). Blostein, Jansen, Jones, Marshall, & Foxman, (2019) indicated that dietary patterns are associated with dental caries in US adults.…”

Comparisons of physical activity, adipokines, vitamin D status and dietary vitamin D intake among adolescents

“…On the other hand, Xu et al . found that consuming foods naturally containing vitamin D was associated with higher 25(OH)D levels among children and adolescents from Hong Kong. The present study found the intake of calcium was also inadequate for almost the entire sample.…”

“…Other studies with Brazilian adolescents have also observed a high proportion of inadequate vitamin D intake: less than 16% of individuals reached the recommendations for this nutrient; however, in both studies, an association between vitamin D from diet and 25(OH)D concentrations was not found (45,46) . On the other hand, Xu et al (47) found that consuming foods naturally containing vitamin D was associated with higher 25(OH)D levels among children and adolescents from Hong Kong. The present study found the intake of calcium was also inadequate for almost the entire sample.…”