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Accurate quantification of whole grains in food is of fundamental importance for research on whole grains and for regulatory and labeling policies, including for checking compliance with regulations around labeling and health claims based on whole grain content. Estimation of whole grain intake requires information about the whole grain content of available foods, yet many products contributing whole grains to the diet do not state the amount or proportion of whole grains present. Since whole grain content in foods can vary from very little to 100%, a large amount of guesswork may go into estimating whole grain content, potentially reducing the accuracy of associations between whole grains and health. Quantifying whole grains in foods is also important for clearly and honestly marketing whole grains to consumers, to ensure consumer confidence that a product labeled as containing whole grains does actually contain what is stated.

In some food cultures, only those foods that contain close to or 100% whole grain ingredients can be called “whole grain,”⁽¹⁾ while in other food cultures, products labeled as “whole grain” may contain <20% of whole grains.⁽²⁾ Scientifically, it is the overall intake of whole grain ingredients that is important for understanding the relationship between whole grains and health, rather than the overall amount of products classified as containing whole grains. Yet, while it is feasible to weigh a slice of bread, it is impossible to know the amount of whole grain ingredients in that slice of bread unless you have access to the recipe or it is stated on the packaging. Ideal methods of quantification would provide accurate estimation of whole grain amount for a wide variety of foods containing whole grains, as even foods with more refined grain flour than whole grain flour may make an important contribution of whole grains to some diets.⁽²⁾ Recognition of whether a product is “whole grain” or contains whole grains is often done based on product appearance. A bread or pasta may be brown, there may be visible bran in the product, or there may be intact grains or seeds visible in the food. These visual cues do not, in fact, tell anything about whether a product is whole grain or not, nor about the proportion of whole grains in a product. Bread can be made to look dark by the addition of caramel coloring; the addition of a small amount of bran can give a product a “grainy” look; and common seeds are not whole grains. The ingredients list may give important clues, as ingredients must be labeled in descending order of amount. This means that a cereal‐based product listing whole grain flour first is quite likely to have >50% of its grain as whole grains. However, this still leaves a large margin of error, especially in foods with multiple refined‐ and whole grain ingredients. In the European Union, ingredients lists follow Quantitative Ingredients Declaration (QUID) law, where, for example, a product labeled as whole grain would need to state the percentage of any whole grain(s) in the ingredients list. This gives the proportion of whole grains in a product, though there is still some leeway for inaccuracy based on the amount of water in a product (see the following).