Nutrient density is the vitamin or mineral content of a food per unit of energy. Energy intake, or calorie need, is regulated by satiety and appetite to a large degree. Energy needs can be satisfied before a person's need for vitamins and minerals is met, advises Judy Anne Driskell and Ira Wolinsky in their book, "Nutritional Assessment of Athletes." Meeting calorie needs without nutrient needs can lead to a deficiency. The trick is to choose foods that fill both needs at the same time, or foods that have a good nutrient density. Whole foods tend to have the most nutrients for their calories. Nutrient density can be calculated for specific foods using the Index of Nutritional Quality, or INQ, rating system.
Take the amount of the nutrient per 100 g and divide it by the recommended daily allowance (RDA) for that nutrient for your age and gender. In an egg, for example, there are 12.4 grams of protein. The RDA for a male adult is 63 grams of protein. So 12.4 divided by 63 gives you about 0.1968.
Take the calories per 100 g of the food and divide it by the recommended daily calorie intake for your age and gender. The egg has 141 calories in 100 grams. The recommended calorie intake for an active adult male is 2,900. Dividing 141 by 2,900 gives you roughly 0.0486.
Divide the number you got using the RDA calculation by the number you got in the calorie calculation. So you will take the 0.1968 and divide it by the 0.0486 to get an answer that roughly equals four. If the food is between two and six, it is considered a good source for that nutrient, or to have good nutrient density under the INQ rating system.
NuVal is a 100-point scoring system for foods that can be utilized at the grocery store.