Interaction between genetic predisposition to obesity and dietary calcium in relation to subsequent change in body weight and waist circumference.
BACKGROUND
Studies indicate an effect of dietary calcium on change in body weight (BW) and waist circumference (WC), but the results are inconsistent. Furthermore, a relation could depend on genetic predisposition to obesity.


OBJECTIVE
The objective was to examine whether genetic predisposition to higher body mass index (BMI), WC, or waist-hip ratio (WHR) interacts with dietary calcium in relation to subsequent annual change in BW (ΔBW) and WC (ΔWC).


METHODS
The study was based on 7569 individuals from the MONItoring trends and determinants of CArdiovascular disease Study, a sample from the Danish Diet, Cancer and Health Study and the INTER99 study, with information on diet; 54 single-nucleotide polymorphisms (SNPs) associated with BMI, WC, or WHR adjusted for BMI; and potential confounders. The SNPs were combined in 4 scores as indicators of genetic predisposition; all SNPs in a general score and a score for each of 3 phenotypes: BMI, WC, and WHR. Linear regression was used to examine the association between calcium intake and ΔBW or ΔWC adjusted for concurrent ΔBW. SNP score × calcium interactions were examined by adding product terms to the models.


RESULTS
We found a significant ΔBW of -0.076 kg (P = 0.021; 95% CI: -0.140, -0.012) per 1000 mg Ca. No significant association was observed between dietary calcium and ΔWC. In the analyses with ΔBW as outcome, we found no significant interactions between the developed predisposition scores and calcium. However, we found a significant interaction between a score of 6 WC-associated SNPs and calcium in relation to ΔWC. Each risk allele was associated with a ΔWC of -0.043 cm (P = 0.038; 95% CI: -0.083, -0.002) per 1000 mg Ca.


CONCLUSIONS
Our study suggests that dietary calcium relates weakly to BW loss. We found no evidence of a general association between calcium and ΔWC, but calcium may reduce WC among people genetically predisposed to a high WC. However, further replication of this finding is needed.
Institute of Preventive Medicine, Bispebjerg and Frederiksberg Hospitals, the Capital Region, Copenhagen, Denmark (SCL, LÄ, BLH, and TIAS); the Novo Nordisk Foundation Center for Basic Metabolic Research, Section on Metabolic Genetics, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark (TSA, OP, TH, and TIAS); the Research Centre for Prevention and Health, Glostrup University Hospital, Glostrup, Denmark (TS, AL, LLNH, UT, and BLH); the Danish Cancer Society Research Center, Copenhagen, Denmark (NR, AT, and JH); the Section of Epidemiology, Department of Public Health, Aarhus University, Aarhus, Denmark (KO); the Department of Cardiology, Aalborg University Hospital, Aalborg, Denmark (KO); the National Institute of Public Health, University of Southern Denmark, Copenhagen, Denmark (BLH); and the Boden Institute of Obesity, Nutrition, Exercise and Eating Disorders, The University of Sydney, Sydney, Australia (BLH).
Sofus C
SC
Larsen
Lars
L
Ängquist
Tarunveer Singh
TS
Ahluwalia
Tea
T
Skaaby
Nina
N
Roswall
Anne
A
Tjønneland
Jytte
J
Halkjær
Kim
K
Overvad
Oluf
O
Pedersen
Torben
T
Hansen
Allan
A
Linneberg
Lise Lotte N
LL
Husemoen
Ulla
U
Toft
Berit L
BL
Heitmann
Thorkild Ia
TIa
Sørensen
D000328:Adult; D015992:Body Mass Index; D002136:Calcium, Dietary / Q000627:therapeutic use*; D015331:Cohort Studies; D003718:Denmark; D004038:Diet, Reducing; D005260:Female; D005500:Follow-Up Studies; D056726:Genetic Association Studies; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D015201:Meta-Analysis as Topic; D009765:Obesity / Q000178:diet therapy* / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D055105:Waist Circumference; D049629:Waist-Hip Ratio; D015430:Weight Gain; D015431:Weight Loss
D002136:Calcium, Dietary