Controversy and Statistical Issues in the Use of Nutrient Densities in Assessing Diet Quality
Forshee, R.A. and Storey, M.L.
Journal of Nutrition, October 2004; 134: 2733-2737
The use of nutrient densities, such as percentage of daily energy from added sugars (%EAS), creates serious statistical analysis and interpretation problems. This article examines the statistical analyses used in the September 2002 National Academy of Sciences’ Institute of Medicine (IOM) draft report on Dietary Reference Intakes for macronutrients. The most critical issues involve the use of a ratio, %EAS, as the key analytic variable and the use of a model that does not properly control for total energy in the diet.
Upon analyzing the same data from the National Health and Nutrition Examination Survey III, an alternative statistical approach using multiple regression to partition total energy into "energy from added sugars" and "energy from other sources" produced very different results than the IOM analysis. Whereas the IOM reported decreasing intakes of calcium, vitamin A, iron, and zinc with increasing %EAS, we found that the association of energy from added sugars with micronutrient intake was inconsistent and small. Energy from other sources had a much stronger and consistent association with micronutrient intake. We conclude that consumption of added sugars has little or no association with diet quality.