Many Chinese have an insufficient vitamin D supply

A new review says that vitamin D deficiency and insufficiency are prevalent in the Chinese population in almost all age groups and areas.
This review analyzed publications that measured plasma/serum 25-hydroxyvitamin-D (25[OH]D) levels in various age groups (newborns, adults and the elderly) in different areas of China (1). The study results showed that vitamin D deficiency (below 25 nmol/L) was phenomenal among the youth: there was no group with desirable 25(OH)D levels (above 75 nmol/L) and as many as 40% to 90% had insufficient blood 25(OH)D levels (lower than 50 nmol/L). A large percentage of adults also had insufficient blood 25(OH)D levels, particularly women of childbearing age and pregnant women in Nanjing, Beijing and Hong Kong. In the elderly, who are fourfold less efficient in sunshine-induced vitamin D production in their skin than the youth and are particularly vulnerable to bone fracture or mobility disorders, the 25(OH)D status was alarming: no participants showed 25(OH)D levels above 50 nmol/L.

The researchers commented that Vitamin D deficiency and insufficiency as a public health risk in mainland China might have been caused by multiple factors, some of which are unique and worthy of being men-tioned. First, with the rapid transformation from an agrarian to an industrialized society, the number of people engaged in an outdoor profession with sun exposure has dramatically decreased. Second, due to air pollution accompanied by industrialization and urbanization, people have been discouraged from spending time outdoors and UVB has been prevented from penetrating the atmosphere. Third, the preference for lighter skin color (fair skin) in the society has remained unchanged, leading to popular use of hats, um-brellas, and sunscreens when outdoors. Concern about UVB radiation-related skin carcinomas has also increased. Fourth, despite massive and successful improvements in macronutrient intakes in the Chinese population, micronutrient intake has not improved in parallel. In fact, natural food rich in vitamin D in the Chinese diet remains scarce, and food and beverages fortified with vitamin D are limited in the market.

The scientists noted that to attain a desirable vitamin D status at the population level, it would require multiple approaches, e.g., the promotion of a healthy lifestyle, the implementation of recommended daily intake, the development of voluntary and mandatory fortification programs, and the establishment of regulations and their reinforcement.

1. Zhang W. et al. Vitamin D status in Mainland China. Nutrition. Published online April 2013.