Nutrients to Include

As the number of recognized biologically active components of foods increases, compilers of food composition tables are faced with an ever-expanding list of possible nutrients and other components to include. Some of these are given in Table 1. The current version of the US Department of Agriculture's Standard Reference Database (release 16-1) contains up to 125 components for each of more than 6600 foods. Because a wide variety of analytic methods is available for determining and reporting nutrient levels in foods, it is useful to have a common convention for naming the nutrients. Many compilers are using standard nutrient names, called tag names, that have been proposed by INFOODS.

Nutrient values in a food composition table normally reflect the level in 100 g of the food item. Thus, the intake of a nutrient from a specific food can be calculated if the amount consumed is recorded in gram weights (e.g., if 100 g of whole milk has 119 mg of calcium, and a person drank a cup of milk weighing 244 g, then the intake of calcium from the cup of milk would be 291 mg). Many food composition tables also contain the weight of typical portions of each food item, and thus the nutrient profile for these portions can readily be calculated.

A related issue is whether to show nutrient profiles per 100 g of the food as consumed or 100 g of the food as purchased. Because some parts of a food may be discarded as inedible, the nutrients per 100 g as purchased will be lower for these foods. For example, a banana skin is approximately one-third of the weight of a banana. If 100 g of a banana without peel has an energy content of approximately 90 kcal, then the energy content of 100 g of banana with peel is only 60 kcal. Composition tables may simply carry a variable for the average percentage of the food that is edible, but it is obviously important to match the method used to measure the food intake (with or without inedible portions) with the way the composition of the food is given in the table.