Apolipoprotein A-II polymorphism: relationships to behavioural and hormonal mediators of obesity

Abstract

Background: The interaction between apolipoprotein A-II (APOA2) m265 genotype and saturated fat for obesity traits has been more extensively demonstrated than for any other locus, but behavioural and hormonal mechanisms underlying this relationship are unexplored. In this study, we evaluated relationships between APOA2 and obesity risk with particular focus on patterns of eating and ghrelin, a hormonal regulator of food intake.

Design: Cross-sectional study.

Subjects: Overweight and obese subjects (n=1225) were evaluated at baseline in five weight loss clinics in southeastern Spain.

Methods: Behavioural data were assessed using a checklist of weight loss obstacles. Logistic regression models were fitted to estimate the risk of a specific behaviour associated with APOA2 genotype. Relationships between APOA2 genotype and saturated fat intakes for anthropometric traits and plasma ghrelin were evaluated by analysis of variance. To construct categorical variables to evaluate interactions, saturated fat intake was dichotomized into high and low according to the population median intake or as tertiles.

Results: Homozygous minor (CC) subjects were more likely to exhibit behaviours that impede weight loss ('Do you skip meals', odds ratio (OR)=2.09, P=0.008) and less likely to exhibit the protective behaviour of 'Do you plan meals in advance' (OR=0.64, P=0.034). Plasma ghrelin for CC subjects consuming low saturated fat was lower compared with (1) CC subjects consuming high saturated fat, (2) TT+TC carriers consuming low saturated fat and (3) TT+TC carriers consuming high saturated fat (all P<0.05).

Conclusions: APOA2 m265 genotype may be associated with eating behaviours and dietary modulation of plasma ghrelin. Expansion of knowledge of APOA2 and obesity to include modulation of specific behaviours and hormonal mediators not only broadens understanding of gene-diet interactions, but also facilitates the pragmatic, future goal of developing dietary guidelines based on genotype.

Figures

Figure 1

Mean waist circumference by APOA2 m265 genotype and saturated fat intake. Error bars indicate standard error (s.e.) of means. Low saturated fat, <20.7 (grams per day) and high saturated fat, <20.7 (grams per day). Means were adjusted for age, gender, centre and physical activity. P-values were obtained through comparisons of means for genotype according to saturated fat intake. P for interaction was obtained for the interaction between genotype and saturated fat intake.

Figure 2

Mean plasma ghrelin (pg ml−1) by APOA2 m265 genotype and tertiles of saturated fat intake (n=425). Lowest saturated fat, <8.1 (percentage of total energy); middle saturated fat, ≥8.1 (percentage of total energy) and <13.1 (percentage of total energy); highest saturated fat, ≥13.1 (percentage of total energy). Means were adjusted for age, gender and centre. P-values were obtained through comparisons of means for genotype according to saturated fat intake. P for interaction was obtained for the interaction between genotype and saturated fat intake. Means marked with different letters differ, P<0.05.