Whole Grains and Health. Группа авторов
Wenche Frølich1 and Per Åman2
1Norwegian School of Hotel Management, University of Stavanger, Lindebergveien 39, N‐1358 Jar, Norway,
2Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden
2.1 Introduction
Worldwide, dietary recommendations are given for increasing the intake of whole grain to improve health and well‐being. There has been a strong international trend to develop and market whole grain foods; however, it has been difficult to obtain reliable and required information for selecting the most desirable products from a nutritional point of view. Even if an increasing number of consumers are well aware that whole grain foods are healthy, they are less informed about the nutritional differences in composition between cereals as well as pseudocereals. In Western populations, whole grain intake comes mainly from wheat, oats, rye, barley and corn. The estimated health risk reductions observed for whole grain in existing studies are therefore most likely due to intake of these particular cereals. It is well known that large regional differences exist in types of grains eaten both within and between countries although reliable and exact information on this intake is scarce (Kyrø et al. 2014). In order to provide consumers with appropriate dietary advices and to give the industry the opportunity to develop and market innovative and healthy foods, well‐defined definitions not only of whole grain but also of whole grain foods are needed. This will help authorities to encourage the producers (industries) to label foods with correct and understandable amounts of whole grain. A common definition of whole grain foods is also important as international research and trade with foods are increasing.
Whole grain cereals are major sources of dietary carbohydrate and protein as well as containing high amounts of a variety of dietary fibres, minerals, vitamins and other bioactive components (Fardet 2010; Andersson et al. 2014). The latter components are mainly present in the outer parts of the grain or in the germ and are therefore removed to a large extent during extraction of sifted flours. As a result, health authorities in many countries are recommending exchanging the sifted flours with whole grain flours. However, evidence‐based recommendations on the exact amounts and types of whole grains to be consumed are still lacking.
Questions that ought to be raised in this context are therefore: Do consumers know what is meant by whole grain? Do they know which grains are included in this group? Are all whole grains or whole grain foods the same when it comes to nutritional content and health effects?
2.2 Definition of whole grain in different countries
With the growing interest in whole grain, not only among researchers and health authorities but also among the consumers and the food industries, an exact and strict definition of whole grain is urgently needed (Frølich and Åman 2010).
The scientific community has for many years been involved in the discussions regarding an international common definition, including issues such as the types and parts of grains that should be included in such a definition. Important aspects in finding an applicable definition is different for target groups: the consumers to facilitate their choice of healthy food alternatives; the scientific community to establish uniform food frequency questioners and standardized dietary factors to study in relation to health; the authorities to be able to make recommendations; and the food industries to produce a variety of new whole grain products. A common international definition of whole grain would certainly benefit all these interests. However, for a definition to be useful in a long‐term perspective for all these groups, it must be grounded on evidence‐based nutritional aspects rather than simply classification of food items. In addition to short definitions launched some decades ago, more recent compressive definitions have been developed in several countries. In these definitions, lists of cereals and pseudocereals are included as well as specifications of the processes allowed to be used (van der Kamp and Lupton 2013).
Cereals are members of the grass family (Poaceae or previously Gramineae) and produce dry one‐seeded fruits (caryopsis) that are commonly called a kernel or grain (Delcour and Hoseney 2010). All cereals consist of a fruit coat (pericarp) surrounding the seed. The seed contains an embryo (germ) and an endosperm surrounded by a nucellar epidermis and a seed coat (testa). In general, all cereals have broadly similar proportions of these botanical structures. However, it is not possible to specify a standard ratio for the different botanical structures since these vary within and between cereals. In addition, some cereals such as rice, oats and barley retain their husk during threshing and this must be removed to produce acceptable foods for humans. Bran is a technical fraction from the milling industry. It generally comprises the fruit wall, seed wall, aleurone layer, germ and smaller amounts of the starchy endosperm. The composition of a bran fraction is highly dependent on the milling technology and type of grain used (Kamal‐Eldin et al. 2009).
Pseudocereals such as amaranth, quinoa and buckwheat are not members of the grass family, but because of the high starch content in their seeds and their use in cereal‐like products, it has been suggested that they should be classified as whole grain together with the cereals in the grass family (Frølich and Åman 2010). These seeds contain no gluten and are therefore suitable alternatives for people with celiac disease. Certain pulses or grain legumes are other seeds with a high content of starch that can be used in different types of cereal‐like products. Because of the characteristics of these, it could be argued if they should also be included in the definition of whole grain; however, they are generally not regarded as such.
2.2.1 AACC International and American Whole Grain Council definitions of whole grain
Whole grain was defined by AACC International (1999): “Whole grain shall consist of the intact, ground, cracked or flaked caryopsis whose principal anatomical components – the starchy endosperm, germ and bran – are present in the same relative proportion as they exist in the intact caryopsis.” From this, it is clear that inclusion or non‐inclusion of grains in this definition is not based on the dietary fibre contents. Pseudocereals (buckwheat, amaranth and quinoa), on the other hand, are included since they are considered to have similar macronutrient composition as whole grain cereals and they are also eaten in similar ways.
The AACC International definition of whole grain was adopted by the US Food and Drug Administration in the document “Whole Grain Label Statements” in 2006, to provide guidance for the industry (Anon. 2006). The American Whole Grain Council (2004) defines whole grain in a similar way to AACC International, using the following wording: “Whole grains or foods made from them contain all the essential parts and naturally‐occurring nutrients of the entire grain seed in their original proportions. If the grain has been processed (e.g., cracked, crushed, rolled, extruded and/or cooked), the food product should deliver approximately the same rich balance of nutrients that are found in the original grain seed.”
This definition includes the following cereals and pseudocereals (and forms of these): Amaranth; barley; buckwheat; corn, including whole cornmeal and popcorn; millet; oats, including oatmeal; quinoa; rice, both brown rice and colored rice; rye; sorghum (also called milo); teff; triticale; wheat, including varieties such as spelt, emmer, farro, einkorn, Kamut®, durum and forms such as bulgur, cracked wheat and wheat berries and wild rice. It also includes more unusual cereals belonging to the grass family such as canary seed, Job’s tears, montana, and fonio when consumed with all of their bran, germ and endosperm.
2.2.2 Whole grain definition in Denmark and the Scandinavian Keyhole
A Danish Task Force from 2008 defined whole grain as intact, ground, cracked or flaked kernels after removal of the husks (Mejborn et al. 2008). In this definition, the nine main cereals within the grass family (barley, oats, wheat, rye, rice, millet, maize, sorghum and triticale) are included, but not the pseudocereals. It is permissible to combine different milling fractions, but the relative proportions of