Whole Grains and Health. Группа авторов
why this is an important challenge to meet.
5.2 Why is it important to know the whole grain content of food?
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).
5.2.1 How whole grain content of cereal products has been reported
Whole grains are a diverse group of cereals and pseudocereals that are on one level well defined as ingredients, but at the level of food products, poorly defined due to no universally accepted definition of what constitutes a whole grain food product. This is further clouded by a wide range of definitions used by scientists, regulatory authorities, private labeling initiatives and what is reported “on pack” for food products containing cereals.
In the scientific literature, the use of “whole grains” to identify foods of potential interest for reducing disease risk, first used a cut‐off point of 25% whole grains (as a percent of total weight as consumed) in a product.(3,4,5) Deciding on a threshold for whether a product would count as being “whole grain” or not was necessary to establish whether there was a relationship between foods containing whole grains and health. However, this also means that a food included as whole grain for the purposes of estimating intake could contain anywhere between 25% and 100% of its total weight as whole grains. A product that contained 26% whole grains would be considered to contribute the same amount of whole grains to overall whole grain intake as a food with 100% whole grain ingredients. Further, using this threshold does not account for products that contain <25% whole grains, so it would not be possible to determine whether such foods make an important contribution to whole grain intake. So while a 25% threshold was a good starting point, as research on whole grains has progressed since the early studies associating whole grain intake with reduced disease risk, it has been necessary to further develop how whole grain intake is estimated and how whole grain content in foods is measured and used to estimate intake.
In 1999, the United States Food and Drug Administration (FDA) allowed a health claim to be made for whole grain foods and cardiovascular disease and some types of cancer. With this health claim came the first set of criteria to define what a whole grain food product was: a food with ≥51% whole grains (by total weight as consumed), low in fat, sugar and salt. Determination of whether a product was whole grain or not was based on the dietary fibre content of wheat – a laudable attempt, but problematic as many commonly consumed cereals have a lower dietary fibre content than wheat – notably rice and corn/maize. The water content of whole grain foods was not addressed, allowing dry foods like RTE breakfast cereal, crackers and pasta to qualify for the FDA health claim much more easily than moist foods like bread. In contrast, a definition developed by the Swedish Nutrition Foundation to support a Swedish health claim for whole grain foods specified that foods needed to have at least 50% whole grain ingredients on a dry weight basis, but that foods could claim “whole grain” on their packaging if they had at least 25% on a dry weight basis, and stated the proportion of whole grains.(6)
5.2.2 Quantifying whole grain content
Much of what is known about whole grain content of food is based on what is reported on food packaging or in recipe books. Few countries have clear guidelines for labeling whole grain content, which limits the value of a product labeled as “whole grain” for estimating intake or for consumer communication. There are three main approaches to quantifying whole grain content in food:
The percentage of the grain ingredients that are whole grain (i.e., whole grain vs. refined grain)
The percentage of the product dry weight that is whole grain (i.e., without the influence of water added during food processing or cooking)
The percentage of the product as consumed that is whole grain (i.e., accounting for non‐grain‐based ingredients)
The United States Dietary Guidelines for Americans, in their practical advice for helping consumers select whole grain products, advise that selecting products with “whole grains as the first ingredient” is a good consumer shortcut for choosing foods that will provide a substantial proportion of whole grains. However, it still falls short as a quantitative tool, and from a regulatory and consumer perspective, requires knowledge about ingredient lists and close‐up investigation of the back of the packaging to make this crude measurement of whole grain content.
Most cereal foods have water added, and depending on what is quantified, this may make a big difference to a whole grain label that is based on percentage of a product’s weight as consumed. For example, dried pasta contains essentially no water, and if made from only whole grain durum wheat, could be labeled as “100% whole grain pasta.” The same pasta cooked and frozen for a ready meal would be only 33% whole grain if reported on a fresh weight basis, although the amount of dry pasta in a serving would be the same. This highlights the need to account for water content when reporting whole grain content in foods.
A further issue is that of the effect of processing – at what point do whole grains become so highly processed that they are no longer whole grain? There are few guidelines and this topic is somewhat out of scope here, though it is worth mentioning that the United States Department of Agriculture (USDA), in 2008, stated that when a shoot from a sprouted cereal seed is longer than the seed itself, then it is no