Qualitative diet indexes: a descriptive or an assessment tool?

Diet diversity indexes were examined as examples of qualitative diet indexes. Diet indexes were calculated from food frequency information grouped according to three food taxonomies or left uncategorized. Two diet indexes linked more closely in their construct to measures of nutrient intake were calculated for comparison purposes. The indexes were assessed on the basis of concordance with biochemical measures of vitamin nutriture, simplicity of calculation, and cultural and nutritional logic. The value of the diet indexes lay in their ability to describe, not to assess, food patterns.