For some nutrition claims, one condition of use is that the nutrient in question must provide a certain percentage of the total energy of the product. For example, the condition for using the claim "source of protein" is that at least 12% of the energy content of the food comes from protein. This is calculated by dividing the amount of energy provided by protein with the total energy of the product.
- 100 g of the product contains 3 g of protein and 100 kcal of energy. The energy provided by protein is 3 g x 4 kcal/g = 12 kcal. The proportion of this from the total energy is 12 kcal / 100 kcal = 12%. Thus, the product contains the required amount of protein to use the claim "source of protein".
The energy provided by fat is calculated similarly, but bearing in mind that one gram of fat provides 9 kcal of energy.