ADJUSTMENT FOR TOTAL-ENERGY INTAKE IN EPIDEMIOLOGIC STUDIES - COMMENTS

Willett et al [Am J Clin Nutr 1997;65(suppl): 1220S-8S] reviewed the c ase for energy adjustment in the analysis of nutritional studies and a rgued strongly for basing the main analysis on an energy-adjustment st atistical model. They recommended focusing attention on a statistical association that represents the change in disease incidence associated with the substitution of energy from a specific nutrient for energy f rom other nutrient sources, while keeping total energy intake constant . Although we agree with many of the points made in their paper, we re commend assessing and reporting associations representing not only the substitution but also the addition of energy from the specific nutrie nt. For these ''addition'' associations, it is especially important to check for confounding with measures of body size and physical activit y. Restricting analyses to substitution associations will confine inve stigators to estimating the relative effects of one nutrient to anothe r and will preclude investigating the effects of increased intake of a specific nutrient.