Genotype-by-nutrient interactions assessed in European obese women. A case-only study.
BACKGROUND
The development of obesity is influenced by both genetic and environmental risk factors. Whereas changes in the environment appear to be responsible for the increasing prevalence of obesity, genetic factors interacting with environmental factors would contribute to explain obesity onset and severity.


OBJECTIVE
To explore epidemiologic genotype-by-nutrient interactions in obesity.


METHODS
A total of 42 polymorphisms of 26 candidate genes for obesity were genotyped in 549 adult obese women recruited from eight European centres in a case-only study. The nutritional variables assessed in this study were the dietary fibre intake (grams per day), the ratio of dietary polyunsaturated fat to saturated fat (P:S ratio) and the percentage of energy derived from fat in the diet as calculated from a weighed three-day food record (%E). Under the assumption of genotype-nutrient independence in the population, the odds ratio calculated in a sample of obese women would indicate the existence of genotype-by-nutrient interactions, measured as deviations from the multiplicative effects of the genetic and the nutrient factors separately.


RESULTS
No new but confirmaty evidences for genotype-by-nutrient interactions in obesity were detected in this case-only study. The test of interaction between fibre intake and the -514 C > T polymorphism of the hepatic lipase gene (LIPC) yielded P-values of 0.01 across different statistical models. Likewise, the -11377G > C polymorphism of the adiponectin gene (ADIPOQ) and the -681 C > G polymorphism of the PPARG3 gene might interact with the percentage of energy derived from fat in the diet for the development of obesity (P-values in the range of 0.01-0.05 across different statistical models). The P-values were not adjusted for multiple testing, so these results should be considered with caution.


CONCLUSIONS
Although the use of obese-only samples is theoretically a useful approach to detect interactions, few genotype-by-nutrient interactions have been suggested in obese European women after the analysis of candidate polymorphisms and the selected nutrient variables. The most remarkable multiplicative interaction found in this study refers to the combination of the hepatic lipase gene polymorphism -514 C > T and fibre intake.
Santos
Jose L
JL
Dept. of Physiology and Nutrition, University of Navarra, 31008, Pamplona, Spain.
Boutin
Philippe
P
Verdich
Camilla
C
Holst
Claus
C
Larsen
Lesli H
LH
Toubro
Soren
S
Dina
Christian
C
Saris
Wim H M
WH
Blaak
Ellen E
EE
Hoffstedt
Johnatan
J
Taylor
Moira A
MA
Polak
Jan
J
Clement
Karine
K
Langin
Dominique
D
Astrup
Arne
A
Froguel
Philippe
P
Pedersen
Oluf
O
Sorensen
Thorkild I A
TI
Martinez
J Alfredo
JA
D052242:Adiponectin / Q000235:genetics*; D000328:Adult; D004041:Dietary Fats / Q000008:administration & dosage; D004043:Dietary Fiber / Q000008:administration & dosage; D004777:Environment; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008049:Lipase / Q000235:genetics*; D008099:Liver / Q000201:enzymology; D008875:Middle Aged; D009765:Obesity / Q000209:etiology / Q000235:genetics*; D047495:PPAR gamma / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide; D012307:Risk Factors
D052242:Adiponectin; D004041:Dietary Fats; D004043:Dietary Fiber; C504173:LIPC protein, human; D047495:PPAR gamma; D008049:Lipase