Serum 25-hydroxyvitamin D and metabolic syndrome in a Japanese working population: The Furukawa Nutrition and Health Study.
OBJECTIVE
Increasing evidence has suggested a protective role of vitamin D on metabolic syndrome (MetS). However, studies addressing this issue are limited in Asia and it remains unclear whether calcium could modify the association. We examined the association of serum 25-hydroxyvitamin D (25(OH)D) status with MetS, and the potential effect modification by calcium intake in a Japanese working population.


METHODS
Study subjects were 1790 workers, ages 18 to 69 y, who participated in a health survey at the time of periodic checkup. MetS was defined according to the joint interim statement. Serum 25(OH)D was measured by a protein binding assay. Multilevel logistic regression was used to estimate the odds ratio (OR) with adjustment for potential confounding variables.


RESULTS
An inverse trend was observed between 25(OH)D and MetS. Compared with those with a 25(OH)D of <20 ng/mL, multivariable adjusted OR (95% confidence interval) for MetS was 0.79 (0.55-1.15) and 0.52 (0.25-1.04) for those with a 25(OH)D of 20 to 29 ng/mL and ≥30 ng/mL, respectively (P for trend = 0.051). Similar association was observed in the analysis using quartile categories of 25(OH)D; the OR in the highest quartile of 25(OH)D compared with the lowest quartile was 0.61 (0.36-1.01) (P for trend = 0.046). This association was noted only in older subjects (≥44 y). The inverse association between serum 25(OH)D and MetS was more pronounced in subjects with high calcium intake. The inverse association between 25(OH)D and MetS appears to be linear according to restricted cubic spline regression. There was inverse, but statistically nonsignificant, associations between 25(OH)D and each component of MetS.


CONCLUSIONS
Our results suggest that higher circulating vitamin D is associated with decreased likelihood of having MetS among Japanese adults.
Department of Epidemiology and Prevention, Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo, Japan. Electronic address: samimarub@ri.ncgm.go.jp.
Shamima
S
Akter
Department of Health Administration, Furukawa Electric Corporation, Tokyo, Japan.
Masafumi
M
Eguchi
Department of Epidemiology and Prevention, Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo, Japan.
Kayo
K
Kurotani
Department of Health Administration, Furukawa Electric Corporation, Tokyo, Japan.
Takeshi
T
Kochi
Department of Epidemiology and Prevention, Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo, Japan.
Ikuko
I
Kashino
Department of Health Administration, Furukawa Electric Corporation, Tokyo, Japan.
Rie
R
Ito
Department of Epidemiology and Prevention, Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo, Japan; Teikyo University Graduate School of Public Health, Tokyo, Japan.
Keisuke
K
Kuwahara
Department of Health Administration, Furukawa Electric Corporation, Tokyo, Japan.
Hiroko
H
Tsuruoka
Department of Health Administration, Furukawa Electric Corporation, Tokyo, Japan.
Isamu
I
Kabe
Department of Epidemiology and Prevention, Center for Clinical Sciences, National Center for Global Health and Medicine, Tokyo, Japan.
Tetsuya
T
Mizoue
D000293:Adolescent; D000328:Adult; D000368:Aged; D044466:Asian People; D001786:Blood Glucose / Q000378:metabolism; D001794:Blood Pressure; D015992:Body Mass Index; D002136:Calcium, Dietary / Q000008:administration & dosage; D002784:Cholesterol / Q000097:blood; D003430:Cross-Sectional Studies; D015444:Exercise; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D016015:Logistic Models; D008297:Male; D024821:Metabolic Syndrome / Q000097:blood / Q000453:epidemiology* / Q000517:prevention & control; D008875:Middle Aged; D055361:Multilevel Analysis; D015999:Multivariate Analysis; D009752:Nutritional Status; D015995:Prevalence; D012307:Risk Factors; D014280:Triglycerides / Q000097:blood; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology*; D055105:Waist Circumference; D055815:Young Adult
D001786:Blood Glucose; D002136:Calcium, Dietary; D014280:Triglycerides; D014807:Vitamin D; D002784:Cholesterol; C104450:25-hydroxyvitamin D
25(OH)D; Cross-sectional studies; Japanese; Metabolic syndrome