The positive effect of dietary vitamin D intake on bone mineral density in men is modulated by the polyadenosine repeat polymorphism of the vitamin D receptor.
BACKGROUND
Few studies have considered the dietary influence of vitamin D intake on bone mineral density (BMD). Numerous studies have examined the association between VDR polymorphism and BMD, but no previous study has examined the joint influence of dietary vitamin D intake and VDR polymorphism on BMD.


METHODS
We therefore conducted a study in 230 men aged 41-76 years of age. BMD was measured with DXA. A second bone scan was performed on average 2.7 years after the first investigation. Dietary habits were assessed by 14 dietary 24-h recall interviews. The polyadenosine (A) VDR genotypes were determined.


RESULTS
Dietary vitamin D intake was associated with BMD at all sites, also after multivariate adjustment. Those in the highest quintile of intake had 9% higher femoral neck BMD (p = 0.004), 6% higher BMD at the lumbar spine (p = 0.06) and 5% higher total body BMD (p = 0.003) compared to men in the lowest quintile of dietary vitamin D intake. However, the positive association between vitamin D intake and BMD was especially apparent among those with the L/L polyadenosine (A) VDR genotype explaining between 10 and 15% of the variability in BMD depending on site (p < 0.004). There was furthermore a trend, in the lumbar spine, of less reduction in BMD with increasing vitamin D intake (p = 0.07) but not at the other sites. Calcium intake conferred no association with BMD.


CONCLUSIONS
Our results indicate that the extent of positive association between dietary vitamin D intake and BMD in men is dependent on VDR polymorphism, a novel conceivable important gene-environmental interaction.
Michaëlsson
Karl
K
Department of Surgical Sciences, Section of Orthopaedics, University Hospital, S-751 85 Uppsala, Sweden. Karl.Michaelsson@surgsci.uu.se
Wolk
Alicja
A
Jacobsson
Annica
A
Kindmark
Andreas
A
Grundberg
Elin
E
Stiger
Fredrik
F
Mallmin
Hans
H
Ljunghall
Sverker
S
Melhus
Håkan
H
D000241:Adenosine / Q000235:genetics; D000328:Adult; D000368:Aged; D001483:Base Sequence; D015519:Bone Density / Q000187:drug effects* / Q000235:genetics*; D002136:Calcium, Dietary / Q000008:administration & dosage; D017931:DNA Primers / Q000235:genetics; D004032:Diet; D006801:Humans; D008297:Male; D008875:Middle Aged; D011108:Polymers; D011110:Polymorphism, Genetic; D018167:Receptors, Calcitriol / Q000235:genetics*; D020449:Repetitive Sequences, Amino Acid; D014807:Vitamin D / Q000008:administration & dosage*
D002136:Calcium, Dietary; D017931:DNA Primers; D011108:Polymers; D018167:Receptors, Calcitriol; D014807:Vitamin D; C069424:polyadenosine; D000241:Adenosine