Adiposity in relation to vitamin D status and parathyroid hormone levels: a population-based study in older men and women.
OBJECTIVE
In small case-control studies, obesity was associated with worse vitamin D status. Our aim was to assess the association of adiposity (anthropometric measures as well as dual energy x-ray absorptiometry) with serum 25-hydroxyvitamin D (25-OH-D) and serum PTH levels in a large population-based study including older men and women.


METHODS
Subjects were participants of the Longitudinal Aging Study Amsterdam and were aged 65 yr and older. In 453 participants, serum 25-OH-D and PTH were determined, and body mass index, waist circumference, waist to hip ratio, sum of skin folds, and total body fat percentage by dual energy x-ray absorptiometry were measured.


RESULTS
After adjustment for potential confounders, higher body mass index, waist circumference, and sum of skin folds were statistically significantly associated with lower 25-OH-D (standardized beta values were -0.136, -0.137, and -0.140, respectively; all P < 0.05) and with higher PTH (0.166, 0.113, and 0.114, respectively; all P < 0.05). Total body fat percentage was more strongly associated with 25-OH-D and PTH (-0.261 and 0.287, respectively; both P < 0.001) compared with anthropometric measures. Total body fat percentage remained associated with 25-OH-D after adjustment for PTH, and with PTH after adjustment for 25-OH-D.


CONCLUSIONS
Precisely measured total body fat is inversely associated with 25-OH-D levels and is positively associated with PTH levels. The associations were weaker if anthropometric measures were used, indicating a specific role of adipose tissue. Regardless of the possible underlying mechanisms, it may be relevant to take adiposity into account when assessing vitamin D requirements.
Snijder
Marieke B
MB
Institute of Health Sciences, Faculty of Earth and Life Sciences, Vrije University, De Boelelaan 1085, 1081 HV Amsterdam, The Netherlands. marieke.snijder@falw.vu.nl
van Dam
Rob M
RM
Visser
Marjolein
M
Deeg
Dorly J H
DJ
Dekker
Jacqueline M
JM
Bouter
Lex M
LM
Seidell
Jaap C
JC
Lips
Paul
P
D000273:Adipose Tissue / Q000378:metabolism*; D000368:Aged; D000369:Aged, 80 and over; D001823:Body Composition; D015992:Body Mass Index; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood*
D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D