A newly released study in The Journal of Nutrition suggests that poor diet quality and intakes of specific food groups partly explain the association between genetic susceptibility to obesity and measures of obesity.
Obesity results from a complex interplay between genetic and environmental factors. The study of gene-environment interaction in obesity is traditionally based on the concept of moderation in which the effects of genes on obesity are examined relative to environmental factors. An alternative approach used to characterize the interplay between genetic and environmental factors in obesity is to use mediation analysis. In that context, mediation is used to assess the extent to which the effects of genes on obesity are explained by intermediate variables such as diet, referred to as mediators. Relatively few studies have used this type of analysis to identify potential mediators of genetic susceptibility to obesity. In particular, diet quality and intakes of specific food groups as potential mediators of genetic susceptibility to obesity remains to be investigated.
To address this knowledge gap, Louis Pérusse (Université Laval,) and colleagues conducted a study to assess the mediating effects of diet quality and specific food groups on genetic susceptibility to obesity, using Body Mass Index (BMI) and waist circumference as measures of obesity. Participants included 422 women and 328 men from the Quebec Family study, an observational study aimed at investigating the contribution of genetic factors on obesity and behaviors related to energy balance. Diet quality, assessed with a score based on total diet, and specific food groups were derived from a 3-day food record. Food items from the food records were classified into 13 groups based on their positive or negative association with weight gain, obesity, or obesity-related health conditions. Genetic risk to obesity was assessed with a polygenic risk score computed from thousands of genetic markers capturing and individual’s overall genetic susceptibility to obesity.
A total of 26.4% of the sample exhibited obesity (BMI > 30 kg/m2) and 29.6% of the sample had abdominal obesity defined as a waist circumference > 88 cm (> 34.6 inches) for women and > 102 cm (> 39.4 inches) for men. Results from the mediation analyses showed that a poor diet quality, a high proportion of energy intake from sugar-sweetened beverages and fat and high-fat foods, and a low proportion of energy intake from fruits (excluding juices), vegetables, total dairy products, and specific dairy products (yogurt and milk) partly mediated the association between genetic susceptibility to obesity and measures of obesity (BMI and waist circumference).
Study results suggest that diet quality and intakes of specific food groups explain a part of the genetic susceptibility to obesity. Interventions aimed at improving diet quality and the consumption of specific food groups may have beneficial effects on body weight and waist circumference in individuals with a genetic predisposition to obesity.
Raphaëlle Jacob, Catherine Bertrand, Clare Llewellyn, Christian Couture, Marie-Ève Labonté, Angelo Tremblay, Claude Bouchard, Vicky Drapeau, Louis Pérusse, Dietary Mediators of the Genetic Susceptibility to Obesity—Results from the Quebec Family Study, The Journal of Nutrition, Volume 152, Issue 1, January 2022, Pages 49–58, https://doi.org/10.1093/jn/nxab356.
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