Date Published: July 31, 2017
Publisher: Public Library of Science
Author(s): Chi-Hsien Huang, Yu-Tung Anton Huang, Yu-Cheng Lai, Cheuk-Kwan Sun, Susanne Kaser.
The prevalence of low vitamin D status in the elderly population of subtropical area and the potential risk/protective factors have not been addressed. This cross-sectional questionnaire-based study, which collected demographic/anthropometric data and information on diet habit and sun exposure, recruited 170 subjects with mean age 70.9±5.6 in rural areas of southern Taiwan. Serum 25-OH vitamin D, calcium, and intact parathyroid hormone were also measured. Using cut-off level of 30 ng/mL, subjects were divided into low (n = 95) and normal (n = 75) serum vitamin D groups. The results demonstrated a low vitamin D status in 30.6% of men and 57.7% of women. Dietary vitamin D intake was another factor associated with vitamin D status (p = 0.02). Logistic regression identified inadequate intake of vitamin D-rich food as the only risk factor for low vitamin D status in men (OR = 4.55, p = 0.01), whereas inadequate sun exposure was the only predictable risk with dose-response relationship in women (low vs. high sun exposure, OR = 6.84, p = 0.018; moderate vs. high sun exposure, OR = 6.67, p = 0.005). In conclusion, low vitamin D status was common in the elderly of subtropical rural areas. Low sun exposure and inadequate dietary vitamin D consumption were associated with a low vitamin D status in females and males, respectively.
Vitamin D, which is one essential nutrient for intestinal calcium absorption to facilitate mineralization of bone , not only helps in maintaining muscle strength and function , but has also been reported to reinforce immunity [3, 4] as well as improve outcomes of cardiovascular diseases [5–7]. At the other end of the spectrum, vitamin D deficiency has been shown to be associated with rickets, osteomalacia, osteoporosis, risk of fracture, and cancers [1, 8–10]. It has also been reported to be associated with colorectal, lung, prostate, breast and ovarian cancer . Consistently, vitamin D supplementation has been reported to reduce all-cause cancer mortality . Moreover, vitamin D supplementation seems to lower the risk of acute respiratory infection and asthma exacerbation [13, 14].
Although vitamin D deficiency and insufficiency are common worldwide, only a few studies have focused on the vitamin D status of the elderly. Moreover, limited surveys were completed in Asian countries so far. One multicenter survey showed a high prevalence of vitamin D deficiency in large cities in China, but no associated risk factors were reported . Accordingly, our survey was designed to explore the risk factors of low vitamin D status in the elderly living in rural areas of Taiwan. Our survey demonstrated an incidence of low vitamin D status up to 44.1% in this population with female predominance (women: 57.7%, men: 30.6%).
In conclusion, low vitamin D status, including vitamin D insufficiency and deficiency, was common in the aged population living in subtropical rural areas. Low sun exposure and inadequate dietary vitamin D consumption were associated with a status of low vitamin D in females and males, respectively.