title: Higher bone resorption excretion in South Asian women vs. White Caucasians and increased bone loss with higher seasonal cycling of vitamin D: Results from the D-FINES cohort study.
abstract: Few data exist on bone turnover in South Asian women and it is not well elucidated as to whether Western dwelling South Asian women have different bone resorption levels to that of women from European ethnic backgrounds. This study assessed bone resorption levels in UK dwelling South Asian and Caucasian women as well as evaluating whether seasonal variation in 25-hydroxyvitamin D [25(OH)D] is associated with bone resorption in either ethnic group. Data for seasonal measures of urinary N-telopeptide of collagen (uNTX) and serum 25(OH)D were analysed from n=373 women (four groups; South Asian postmenopausal n=44, South Asian premenopausal n=50, Caucasian postmenopausal n=144, Caucasian premenopausal n=135) (mean (±SD) age 48 (14) years; age range 18-79years) who participated in the longitudinal D-FINES (Diet, Food Intake, Nutrition and Exposure to the Sun in Southern England) cohort study (2006-2007). A mixed between-within subjects ANOVA (n=192) showed a between subjects effect of the four groups (P<0.001) on uNTX concentration, but no significant main effect of season (P=0.163). Bonferroni adjusted Post hoc tests (P≤0.008) suggested that there was no significant difference between the postmenopausal Asian and premenopausal Asian groups. Season specific age-matched-pairs analyses showed that in winter (P=0.04) and spring (P=0.007), premenopausal Asian women had a 16 to 20nmolBCE/mmol Cr higher uNTX than premenopausal Caucasian women. The (amplitude/mesor) ratio (i.e. seasonal change) for 25(OH)D was predictive of uNTX, with estimate (SD)=0.213 (0.015) and 95% CI (0.182, 0.245; P<0.001) in a non-linear mixed model (n=154). This showed that individuals with a higher seasonal change in 25(OH)D, adjusted for overall 25(OH)D concentration, showed increased levels of uNTX. Although the effect size was smaller than for the amplitude/mesor ratio, the mesor for 25(OH)D concentration was also predictive of uNTX, with estimate (SD)=-0.035 (0.004), and 95% CI (-0.043, -0.028; P<0.001). This study demonstrates higher levels of uNTX in premenopausal South Asian women than would be expected for their age, being greater than same-age Caucasian women, and similar to postmenopausal Asian women. This highlights potentially higher than expected bone resorption levels in premenopausal South Asian women which, if not offset by concurrent increased bone formation, may have future clinical and public health implications which warrant further investigation. Individuals with a larger seasonal change in 25(OH)D concentration showed an increased bone resorption, an association which was larger than that of the 25(OH)D yearly average, suggesting it may be as important clinically to ensure a stable and steady 25(OH)D concentration, as well as one that is high enough to be optimal for bone health.
authors.affiliation: Department of Nutritional Sciences, Faculty of Health and Medical Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey GU2 7XH, UK. Electronic address: a.l.darling@surrey.ac.uk.
authors.forename: A L
authors.initials: AL
authors.lastname: Darling
authors.affiliation: Department of Nutritional Sciences, Faculty of Health and Medical Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey GU2 7XH, UK.
authors.forename: K H
authors.initials: KH
authors.lastname: Hart
authors.affiliation: Bone Biochemistry Laboratory, Department of Human Metabolism, University of Sheffield, Sheffield S10 2RX, UK.
authors.forename: F
authors.initials: F
authors.lastname: Gossiel
authors.affiliation: Department of Nutritional Sciences, Faculty of Health and Medical Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey GU2 7XH, UK.
authors.forename: F
authors.initials: F
authors.lastname: Robertson
authors.affiliation: Department of Nutritional Sciences, Faculty of Health and Medical Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey GU2 7XH, UK.
authors.forename: J
authors.initials: J
authors.lastname: Hunt
authors.affiliation: School of Agriculture, Food and Rural Development and Human Nutrition Research Centre, Agriculture Building, Newcastle University, NE1 7RU, UK.
authors.forename: T R
authors.initials: TR
authors.lastname: Hill
authors.affiliation: Surrey Clinical Research Centre, University of Surrey, Guildford, Surrey GU2 7XH, UK.
authors.forename: S
authors.initials: S
authors.lastname: Johnsen
authors.affiliation: Specialist Assay Laboratory (Vitamin D), Manchester Academic Health Sciences Centre, Manchester Royal Infirmary, M13 9WL, UK.
authors.forename: J L
authors.initials: JL
authors.lastname: Berry
authors.affiliation: Bone Biochemistry Laboratory, Department of Human Metabolism, University of Sheffield, Sheffield S10 2RX, UK.
authors.forename: R
authors.initials: R
authors.lastname: Eastell
authors.affiliation: Department of Pathology and Laboratory Medicine, Mount Sinai Hospital, 600 University Ave., Toronto, ON M5G 1X5, Canada.
authors.forename: R
authors.initials: R
authors.lastname: Vieth
authors.affiliation: Department of Nutritional Sciences, Faculty of Health and Medical Sciences, School of Biosciences and Medicine, University of Surrey, Guildford, Surrey GU2 7XH, UK.
authors.forename: S A
authors.initials: SA
authors.lastname: Lanham-New
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D044466:Asian People; D001862:Bone Resorption; D015331:Cohort Studies; D024042:Collagen Type I / Q000652:urine*; D005260:Female; D006801:Humans; D008875:Middle Aged; D010455:Peptides / Q000652:urine*; D012621:Seasons; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D044465:White People; D055815:Young Adult
chemical_list: D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D014807:Vitamin D; C104450:25-hydroxyvitamin D
keywords: 25-Hydroxyvitamin D; Bone resorption; Ethnicity; Season; Urinary N-telopeptide