Applied nutritional investigationLow serum concentrations of 25-hydroxyvitamin D in young adult Japanese women: a cross sectional study
Introduction
Vitamin D nutrition status, which is most closely reflected by the serum concentration of 25-hydroxyvitamin D (25[OH]D), the stable form of vitamin D metabolized in the liver,1 is a topic currently of interest in relation to bone health. Insufficient serum concentrations of 25(OH)D are thought to lead to secondary hyperparathyroidism, which is a contributing factor to the age-related acceleration of bone loss.2, 3
Vitamin D insufficiency is common in elderly people and seems to be a serious health problem.4 Vitamin D insufficiency in the elderly has been explained mainly by an age-related decrease in serum 25(OH)D concentration, probably resulting from a reduction in vitamin D biosynthesis in the skin.5, 6 Contrary to expectations, low levels of serum 25(OH)D have been recently reported in young women.7 In comparison with the large number of epidemiologic studies on the vitamin D nutrition in elderly women, however, there have been fewer studies in young women.
We reported low serum 25(OH)D concentrations in female Japanese college students,7 but that study was not designed to compare the serum 25(OH)D concentrations of young adult women with those of their older counterparts. Environmental factors such as seasons and occupation (indoor versus outdoor) are important determinants of serum 25(OH)D concentration because of their relation to ultraviolet exposure and may have considerably affected the results of the study. Thus, a better designed epidemiologic study was needed to confirm our preliminary findings.
To address the question of whether young adult women have inadequate vitamin D nutrition status, we studied a wide age range of adult working women in the same setting. The purposes of the present study were to assess the serum 25(OH)D concentrations of young adult Japanese women in comparison with their older counterparts and evaluate the effects of low 25(OH)D concentrations by simultaneously evaluating other calcium-regulating hormones, in particular parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D (1,25[OH]2D), and bone mass.
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Subjects and methods
We targeted an accessible adult female population—127 healthy women working at three nursing homes in Niigata (latitude 37°48 to 59′N), Japan-and 80 (63.0%), aged 19 to 66 y, agreed to participate in this study. Three of the women were taking vitamin D supplements and were excluded. No subject was taking any sex steroid hormones or medication for osteoporosis. Ultimately, 77 women were included in the analysis. The subjects were engaged in ordinary daytime work, but 39 subjects were also on
Results
The mean age of the subjects was 32.9 y (SD = 11.3), and their mean body weight was 52.0 kg (SD = 6.2). Subjects’ average serum 25(OH)D3 concentration was 42.0 nmol/L (SD = 15.1). Serum 25(OH)D2 was detected in only three subjects (2.1, 2.4, and 3.1 nmol/L). The mean concentration of serum 25(OH)D, the sum of the serum 25(OH)D3 and 25(OH)D2 values, was 42.1 nmol/L (SD = 15.1). The mean serum 25(OH)D concentrations of the 10-y age groups are shown in Fig. 1. The mean serum 25(OH)D
Discussion
The present study clearly demonstrated that the women younger than 30 y had lower serum 25(OH)D concentrations (mean = 34.0 nmol/L) than the women aged 30 to 66 y. This finding conflicts with the current belief that vitamin D nutrition status, i.e., that serum 25(OH)D concentrations decrease with age.5, 6 Moreover, when a serum 25(OH)D concentration cutoff value of 30 nmol/L was adopted, the prevalence of vitamin D insufficiency in women in their 20s was 42.1%, which is close to the rate
Acknowledgements
The authors thank the staffs of the nursing homes Atagonosono, Honaminosato, and Hoseien for their helpful assistance in data collection. They also thank Toyo Medic Inc. for allowing us to use the DTX-200 Osteometer.
References (25)
Vitamin D and bone health
J Nutr
(1996)- et al.
Secondary hyperparathyroidism in elderly peoplecombined effect of renal insufficiency and vitamin D deficiency
Am J Clin Nutr
(1993) - et al.
Serum 25-hydroxyvitamin Ddistribution and determinants in the Swiss population
Am J Clin Nutr
(1992) - et al.
Age-dependent vitamin D status and vertebral condition of white women living in Curaçao (The Netherlands Antilles) as compared with their counterparts in The Netherlands
Am J Clin Nutr
(1993) - et al.
Serum 25-hydroxyvitamin D concentrations and related dietary factors in peri- and postmenopausal Japanese women
Am J Clin Nutr
(2000) - et al.
Serum vitamin D concentrations among elderly people in Europe
Lancet
(1995) - et al.
Seasonal changes in plasma 25-hydroxyvitamin D concentrations of young American black and white women
Am J Clin Nutr
(1998) - et al.
Are the serum 25-hydroxyvitamin D concentrations in winter associated with forearm bone mineral density in healthy elderly Japanese women?
Int J Vitam Nutr Res
(2001) - et al.
Influence of cognitive eating restraint on total-body measurements of bone mineral density and bone mineral content in premenopausal women aged 18–45 ya cross sectional study
Am J Clin Nutr
(2000) - et al.
Healthy elderly French women living at home have secondary hyperparathyroidism and high bone turnover in winter
J Clin Endocrinol Metab
(1996)
Vitamin D deficiency in old people
J Am Geriatr Soc
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