The study of more than 5,000 residents, published in Clinical Nutrition, is the first to investigate the prevalence of vitamin D deficiency among people of all ages living in urban Beijing – finding that nearly 90% the population may not get enough of the sunshine vitamin.
Led by Zhiwei Ning from Beijing Chaoyang Hospital and Capital Medical University, China, the research team, noted that the rapid industrialization of northern China has considerably worsened air pollution, and that this air pollution potentially reduces the penetration of UV-B radiation from the sun. In particular, the area of Hebei which surrounds Beijing, is the top one air polluted province in China, said the team.
“We found an extremely high prevalence of vitamin D deficiency among urban Beijing health checkup population in a cross-sectional, high-scale study in an urban hospital,” wrote the team.
“These findings suggest that vitamin D deficiency is a severe health problem in urban Beijing, among females, especially in spring and winter.”
The Chinese team added that very few foods consumed in the Beijing region are naturally rich in vitamin D, and that it is rare for food products to be fortified with vitamin D in China as they are in other nations.
As a result, vitamin D intake is generally less than 100 IU/d, they warned.
“Vitamin D supplements are recommended as a more effective way to prevent and treat its deficiency,” wrote Ning and colleagues. “Unfortunately, no ideal vitamin D supplements are available in drug stores of Beijing and whole China.”
Urban populations at risk
The Beijing team recruited 5,531 people living in the urban Beijing and followed them for two years to assess seasonal and monthly serum 25(OH)D variation in the population.
Each participant completed a questionnaire designed to quantify intake of vitamin D through food, vitamin D supplements, hours of sun exposure, sunscreen use over the past month, in addition to blood concentrations of vitamin D being measured via serum 25(OH)D, said the researchers.
The prevalence of vitamin D deficiency in the total study population was reported to be 87.1% - with a higher prevalence found in women (89.0%) than men (84.9%).
“Severe vitamin D deficiency is also higher in female than male (59.3% and 42.7%, respectively),” wrote the team, who noted that females under 20 and over 80 have lower 25(OH)D levels compared to 40 to 60 years olds.
“Targeted prevention on vitamin D deficiency is urgent for this population,” they warned.
Source: Clinical Nutrition
Volume 35, Issue 4, Pages 859–863, doi: 10.1016/j.clnu.2015.05.019
“High prevalence of vitamin D deficiency in urban health checkup population”
Authors: Zhiwei Ning, et al