Macronutrients, energy intake, and breast cancer risk: implications from different models.

We used data from a case-control study, conducted in Italy on 2,569 incident cases of breast cancer and 2,588 controls, to fit various energy adjustment models in the estimate of the effect of selected nutrients and alcohol on breast cancer risk. When we fit the standard multivariate and residual models, including total energy intake and the different macronutrients one at a time, the odds ratios (OR) related to 100 kcal per day were 0.90 for protein, 0.96 for saturated fat, 0.88 for unsaturated fat, 0.95 for sugar, 1.07 for starch, and 1.06 for alcohol. When we included all of the different sources of calorie intake in a single model with energy sources partitioned, the OR of adding 100 kcal per day was 0.91 for protein, 1.22 for saturated fat, 0.89 for unsaturated fat, 0.98 for sugar, 1.08 for starch, and 1.07 for alcohol. The estimates from the residual models that included various macronutrients separately were similar to those of the extended energy partition model.