Wheat is an important source of calories (derived from starch), protein, dietary fibre, minerals, vitamins and health-promoting phytochemicals to the human diet. However, many of the beneficial components are concentrated in the outer layers of the grain (bran) and embryo (germ). Consequently, whereas the consumption of whole grain products has health benefits in reducing the risk of a number of medical conditions including the metabolic syndrome, the consumption of highly refined products derived from the starchy endosperm (white flour) may be associated with increased risk. This work will therefore discuss the composition of the wheat grain, focusing on components which positively or negatively affect health outcomes and their distributions in grain tissues and fractions. It will also discuss strategies for developing new types of wheat with improved health benefits, focusing on the three major components in the grain: protein, starch and dietary fibre. Classical plant breeding can be used to increase the content and improve the composition of dietary fibre in flour and wholemeal, exploiting the existence of wide variation in composition and high genetic heritability (Ward et al. 2008; Shewry et al. 2010), and using molecular markers for selection. In particular, increasing the content of soluble fibre content leads to increased intestinal viscosity and reduced glycaemic index (with reduced risk of type-2 diabetes). The glycaemic index of wheat products can also be reduced by increasing the amylose content of starch, and increases from 25% to 40% amylose can be achieved by combining naturally occurring or induced mutations in genes controlling the synthesis of amylopectin (Sestili et al. 2010). The nutritional quality of wheat protein is limited by the low contents of essential amino acids, notably lysine, in the gluten protein fraction. Although high lysine mutations have been studied widely in maize and barley, they have achieved little commercial success and this approach has not been adopted in hexaploid bread wheat. However, lessons learned from studies in these cereals should allow the use of genetic engineering to improve the protein quality of wheat. The combination of these traditional and novel approaches will allow the development of new types of wheat with enhanced nutritional quality and health benefits for wholegrain and white products.
