Adjustment for total energy intake in epidemiologic studies

• Published in: The American journal of clinical nutrition 1997-04, Vol.65 (4), p.1220S-1228S
• Main Authors: Willett, WC, Howe, GR, Kushi, LH
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Coronary Disease - epidemiology; Diet; Energy Intake; Epidemiology; Feeding. Feeding behavior; Fundamental and applied biological sciences. Psychology; Humans; Models, Statistical; Nutritional Physiological Phenomena; Vertebrates: anatomy and physiology, studies on body, several organs or systems
• ISSN: 0002-9165; 1938-3207
• DOI: 10.1093/ajcn/65.4.1220S

In epidemiologic studies, total energy intake is often related to disease risk because of associations between physical activity or body size and the probability of disease. In theory, differences in disease incidence may also be related to metabolic efficiency and therefore to total energy intake. Because intakes of most specific nutrients, particularly macronutrients, are correlated with total energy intake, they may be noncausally associated with disease as a result of confounding by total energy intake. In addition, extraneous variation in nutrient intake resulting from variation in total energy intake that is unrelated to disease risk may weaken associations. Furthermore, individuals or populations must alter their intake of specific nutrients primarily by altering the composition of their diets rather than by changing their total energy intake, unless physical activity or body weight are changed substantially. Thus, adjustment for total energy intake is usually appropriate in epidemiologic studies to control for confounding, reduce extraneous variation, and predict the effect of dietary interventions. Failure to account for total energy intake can obscure associations between nutrient intakes and disease risk or even reverse the direction of association. Several disease-risk models and formulations of these models are available to account for energy intake in epidemiologic analyses, including adjustment of nutrient intakes for total energy intake by regression analysis and addition of total energy to a model with the nutrient density (nutrient divided by energy).