Dairy calcium intake, serum vitamin D, and successful weight loss.
BACKGROUND
The role of dairy calcium intake and serum vitamin D concentrations in weight loss is controversial.


OBJECTIVE
The objective was to assess the association of dairy calcium intake and serum vitamin D with weight loss.


METHODS
We analyzed data from participants in the 2-y Dietary Intervention Randomized Controlled Trial (DIRECT) [n = 322; mean body mass index (BMI; in kg/m²): 31; mean age: 52 y]. A representative sample (n = 126) was followed for 6 mo for serum vitamin D changes.


RESULTS
Baseline serum 25-hydroxyvitamin D [25(OH)D] concentrations decreased significantly across the tertiles of baseline BMI (25.6 ± 8.0, 24.1 ± 8.9, and 22.9 ± 6.8 ng/mL, respectively; P for trend = 0.02). Baseline concentrations of vitamin D and dairy calcium intake were not associated with subsequent weight loss. However, in repeated-measures models adjusted for age, sex, baseline BMI, total fat intake, and diet group assignment, higher 6-mo tertile levels of dairy calcium intake (median for tertiles: 156.5, 358.0, and 582.9 mg/d, respectively) and serum 25(OH)D (14.5, 21.2, and 30.2 ng/mL, respectively) were associated with increased weight loss across the 2-y intervention (-3.3, -3.5, and -5.3 kg, respectively, for dairy calcium; P = 0.043; -3.1, -3.8, and -5.6 kg, respectively, for vitamin D; P = 0.013). In a multivariate logistic regression adjusted simultaneously for age, sex, baseline BMI, total fat intake, diet group, vitamin D concentration, and dairy calcium, an increase of 1 SD in dairy calcium intake increased the likelihood of weight loss of >4.5 kg in the preceding 6 mo [odds ratio (OR): 1.45; P = 0.046]. A similar increase was seen for serum 25(OH)D at the 6-mo point (OR: 1.7; P = 0.009).


CONCLUSIONS
Our study suggests that both higher dairy calcium intake and increased serum vitamin D are related to greater diet-induced weight loss. This trial was registered at clinicaltrials.gov as NCT00160108.
Shahar
Danit R
DR
S Daniel Abraham Center for Health and Nutrition and the Department of Epidemiology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel. dshahar@bgu.ac.il
Schwarzfuchs
Dan
D
Fraser
Drora
D
Vardi
Hillel
H
Thiery
Joachim
J
Fiedler
Georg Martin
GM
Blüher
Matthias
M
Stumvoll
Michael
M
Stampfer
Meir J
MJ
Shai
Iris
I
D000328:Adult; D015992:Body Mass Index; D002136:Calcium, Dietary / Q000008:administration & dosage*; D003611:Dairy Products; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000178:diet therapy*; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D015431:Weight Loss
D002136:Calcium, Dietary; D014807:Vitamin D; C104450:25-hydroxyvitamin D