Studies of Twins Indicate That Genetics Influence Dietary Intake

Habitual dietary intake is a complex behavior that may have both biological and nonbiological bases. We estimated the contribution of genetic and environmental influences on dietary intake in a large population-based sample of healthy twins. Data originated from a cross-sectional study of 600 male and female healthy twin pairs with self-reported food consumption frequency using a validated questionnaire with 247 foods and recipes. Estimates of relative proportion of additive genetic, nonadditive genetic, shared environmental, and unshared environmental effects on various aspects of dietary intake were obtained by quantitative genetic modeling of twin data based on linear structural equations. The analyses demonstrated genetic influence on total energy, macronutrient energy, and dietary fiber intakes, the glycemic index and the glycemic load of the foods consumed, and the dietary energy density, with significant heritability estimates ranging from 0.25 (0.11-0.38) to 0.47 (0.31-0.60) in men and 0.32 (0.12-0.48) to 0.49 (0.35-0.61) in women. When analyzing dietary intake as the intake of energy from 20 food groups, the genetic and environmental influences differed among food groups and between gender. For some food groups (fruit for both genders, poultry and eggs for men), no genetic influence was found, whereas nonadditive genetic effects were demonstrated for other food groups (juices and eggs for women). A number of food groups had shared environmental influences (potatoes, vegetables, fruits, poultry, fish, margarine, and candy). These results provide evidence for both genetic and shared environmental effects on dietary intake. Although the remaining nonshared environmental effects include measurement errors, there appears to be considerable potential for individually modifiable effects. J. Nutr. 138: 2406-2412, 2008.