Table 2.

Three commonly used food price metrics and indication of when their application is most appropriate.

Food price metric	Price per unit of mass	Price per portion	Price per unit of energy
Best used for	Comparing prices of nutritionally similar foods in the context of consumer choice, where mass is likely to be the only product information available to the purchaser.	Comparing prices in the context of direct substitutions of one food for another. This is likely to be of use for analyzing food-based policies that promote such substitutions.	Comparing prices in the context of public health and food security, where the quality of a diet consumed for survival is of concern.
Potential concerns	Limited relevance for assessing the cost of abating hunger or achieving sustenance.	Requires accurate and appropriate portion size data for the population being studied and portions estimated for a different population may lead to inaccurate findings being reported if misapplied.	Calorie information is not always available. Calorie-based comparisons might not be relevant for some consumer decision making.