Association of physical activity and bone: influence of vitamin D receptor genotype.
OBJECTIVE
The aim of the study was to investigate the interaction between leisure physical activity and a BsmI polymorphism at the vitamin D receptor (VDR) gene on the modulation of bone mineral density (BMD).


METHODS
We studied 575 unrelated healthy postmenopausal women. Lumbar spine and femoral neck BMD were measured by dual-energy x-ray absorptiometry (DXA), and results were expressed as age-and-weight-adjusted (Z-score). VDR BsmI genotype was determined by polymerase reaction chain on peripheral blood leukocytes.


RESULTS
Overall, no significant association was found between the level of leisure physical activity or VDR genotypes and adjusted BMD at both bone sites. However, in active women, there was a trend for an association between VDR genotypes and adjusted BMD at the lumbar spine. Active women, who exercised three times or more a week, carrying the "bb" genotype had a lower BMD at the lumbar spine than active women carrying "BB" genotype (ANOVA; P = 0.04). No significant difference in crude or adjusted BMD at both bone sites was found between VDR genotypes in sedentary or moderately active women. Furthermore, classification of women according to the median-age of the sample (63.1 yr) revealed a significant interaction between the level of leisure physical activity and VDR genotype on adjusted lumbar spine BMD in the older active postmenopausal women (N = 137). Older active women carrying the "bb" genotype showed a lower adjusted BMD at the lumbar spine compared with active women carrying the "BB" genotype (P = 0.007).


CONCLUSIONS
These results suggested that gene-environment interactions such as leisure physical activity and VDR genotype may play a role in maintaining the BMD at the lumbar spine in active postmenopausal women, especially in older active women.
Blanchet
Claudine
C
Unité de recherche en endocrinologie de la reproduction, Centre Ménopause Québec, Pavillon St-François D'Assise, CHUQ, Québec, Canada.
Giguère
Yves
Y
Prud'homme
Denis
D
Dumont
Marcel
M
Rousseau
François
F
Dodin
Sylvie
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology; D001835:Body Weight; D015519:Bone Density / Q000235:genetics* / Q000502:physiology*; D015252:Deoxyribonucleases, Type II Site-Specific; D015444:Exercise / Q000502:physiology*; D005260:Female; D005272:Femur Neck / Q000502:physiology; D005838:Genotype; D006801:Humans; D008019:Life Style; D008159:Lumbar Vertebrae / Q000502:physiology; D008875:Middle Aged; D012150:Polymorphism, Restriction Fragment Length; D017698:Postmenopause / Q000502:physiology*; D018167:Receptors, Calcitriol / Q000235:genetics* / Q000502:physiology
D018167:Receptors, Calcitriol; C053864:endodeoxyribonuclease BsmI; D015252:Deoxyribonucleases, Type II Site-Specific