Low 25-hydroxyvitamin D concentrations in obese women: their clinical significance and relationship with anthropometric and body composition variables.
Obesity is associated with low concentrations of 25-hydroxyvitamin D [25(OH) D]. However, conflicting results have been found regarding the relationship of 25(OH) D with anthropometric and adiposity parameters. The aim of our study was to analyze the association between 25(OH) D and body fat (BF) in a homogeneous cohort of non-obese, obese, and morbidly obese Caucasian women. The study was performed in L'Hospitalet de Llobregat, a city adjacent to Barcelona with a latitude of 41 degrees, 22 minutes, and 5 seconds north.


METHODS
Plasma concentrations of 25(OH) D were determined and body composition was evaluated by bioelectrical impedance in a group of 43 women with morbid obesity, 28 non-morbidly obese, and 50 non-obese women matched for age.


RESULTS
Morbidly obese women showed lower 25(OH) D concentrations compared to non-morbidly and non-obese women (37.9+/-16 vs 40.2+/-13 vs 56.7+/-21 nmol/l, p=0.001). Fifty-one percent of morbidly obese women had vitamin D deficiency [25(OH) D<38 nmol/l] compared to 22% of non-obese patients, (p=0.004). In the bivariate correlation analysis 25(OH) D was inversely associated with weight (r=-0.41, p=0.001), body mass index (BMI) (r=-0.432, p=0.001), waist to hip ratio (WHR)(r=-0.40, p=0.001), BF (r=-0.53, p=0001), fat mass (r=-0.44, p=0.0001), fat-free mass (r=-0.35, p=0.001). In the multivariate general linear model analysis, 25(OH) D was associated with season of examination (p=0.001) and was negatively associated with BF (beta=-0.75, p=0.001), after adjusting for age, BMI, and WHR.


CONCLUSIONS
25(OH) D concentrations are associated with body composition variables especially by BF, independently of seasonal variability. Therefore, body adiposity should be considered when assessing vitamin D requirements in obese patients.
Vilarrasa
N
N
Endocrinology and Diabetes Unit, Bellvitge Universitary Hospital, Barcelona, Spain. nuriavilarrasa@yahoo.es
Maravall
J
J
Estepa
A
A
Sánchez
R
R
Masdevall
C
C
Navarro
M A
MA
Alía
P
P
Soler
J
J
Gómez
J M
JM
D050154:Adiposity; D000328:Adult; D000886:Anthropometry; D001823:Body Composition; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008875:Middle Aged; D009767:Obesity, Morbid / Q000097:blood* / Q000453:epidemiology* / Q000473:pathology; D015995:Prevalence; D013030:Spain / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000453:epidemiology*; D044465:White People / Q000706:statistics & numerical data*
D014807:Vitamin D; C104450:25-hydroxyvitamin D