Vitamin D and parathyroid hormone status in a representative population living in Macau, China

Associations between documented sun-exposure, exercise patterns and fish and supplement intake and 25-hydroxyvitamin D (25OHD) and parathyroid hormone (PTH) were investigated in a random household survey of Macau residents (aged 18-93). Blood samples (566) taken in summer were analyzed for 25OHD and PTH. In this Chinese population, 55% were deficient (25OHD < 50 nmol/L: median (interquartile range) = 47.7 (24.2) nmol/L). Vitamin D deficiency was greatest in those aged <50 years: median (interquartile range) = 43.3 (18.2) nmol/L, females: median (interquartile range) = 45.5 (19.4) nmol/L and those with higher educational qualifications: median (interquartile range) = 43.1 (18.7) nmol/L. In the total Macau population, statistically significant (p < 0.01) modifiable associations with lower 25OHD levels were sunlight exposure (β = 0.06), physical activity (PA) (measured as hours(hrs)/day: β = 0.08), sitting (measured as hrs/day β = -0.20), intake of fish (β = 0.08) and calcium (Ca) supplement intake (β = 0.06) [linear regression analysis adjusting for demographic risk factors]. On similar analysis, and after adjustment for 25OHD, the only significant modifiable associations in the total population with PTH were sitting (β = -0.17), Body Mass Index (β = 0.07) and Ca supplement intake (β = -0.06). In this Macau population less documented sun exposure, fish and Ca supplement intake and exercise were associated with lower 25OHD levels, especially in the younger population, along with the interesting finding that more sitting was associated with both lower 25OHD and high PTH blood levels. In conclusion, unlike findings from Caucasian populations, younger participants were significantly more vitamin D deficient, in particular highly educated single females. This may indicate the desire of young females to be pale and avoid the sun. There are also big differences in lifestyle between the older generation and the younger, in particular with respect to sun exposure and PA. This article is part of a Special Issue entitled '17th Vitamin D Workshop'.