Nutrition Bulletin 

Abstract: Summary Resistant starch (RS) refers to the portion of starch and starch products that resist digestion as they pass through the gastrointestinal tract. RS is an extremely broad and diverse range of materials and a number of different types exist (RS1–4). At present, these are mostly defined according to physical and chemical characteristics. RS may be categorised as a type of dietary fibre, as defined by the American Association of Cereal Chemists and the Food Nutrition Board of the Institute of Medicine of the National Academies. RS is measured in part by the methodology recommended by the Association of Official Analytical Chemists for measuring dietary fibre. Dietary intakes of RS in westernised countries are likely to be low. However, accurate comparative assessments of dietary intakes between countries, and subsequent epidemiological analysis, are absent due to the lack of consensus over of an agreed, repeatable and simple in vitro method for analysing the RS content of foods. At present, the recognised method is that of McCleary & Monaghan (2002). RS appears to confer considerable benefits to human colonic health, but has a smaller impact on lipid and glucose metabolism. Comparisons between studies are hampered by differences in study design, poor experimental design and differences in the source, type and dose of RS in the ingredients or diets used. It is likely that RS mediates some or all of its effects through the action of short chain fatty acids but interest is increasing regarding its prebiotic potential. There is also increasing interest in using RS to lower the energy value and available carbohydrate content of foods. RS can also be used to enhance the fibre content of foods and is under investigation regarding its potential to accelerate the onset of satiation and to lower the glycaemic response. Due to the difficulties in agreeing on a universal definition and method of analysis for dietary fibre, RS may be included within the term ‘fibre’ on the nutrition labels in some countries but not in others. Pressure to agree a legal definition and universal method of analysis is likely to increase due to the potential of RS to enhance colonic health, and to act as a vehicle to increase the total dietary fibre content of foodstuffs, particularly those which are low in energy and/or in total carbohydrate content.

Abstract: In recent years, there have been reports suggesting a high prevalence of low vitamin D intakes and vitamin D deficiency or inadequate vitamin D status in Europe. Coupled with growing concern about the health risks associated with low vitamin D status, this has resulted in increased interest in the topic of vitamin D from healthcare professionals, the media and the public. Adequate vitamin D status has a key role in skeletal health. Prevention of the well-described vitamin D deficiency disorders of rickets and osteomalacia are clearly important, but there may also be an implication of low vitamin D status in bone loss, muscle weakness and falls and fragility fractures in older people, and these are highly significant public health issues in terms of morbidity, quality of life and costs to health services in Europe. Although there is no agreement on optimal plasma levels of vitamin D, it is apparent that blood 25-hydroxyvitamin D [25(OH)D] levels are often below recommended ranges for the general population and are particularly low in some subgroups of the population, such as those in institutions or who are housebound and non-Western immigrants. Reported estimates of vitamin D status within different European countries show large variation. However, comparison of studies across Europe is limited by their use of different methodologies. The prevalence of vitamin D deficiency [often defined as plasma 25(OH)D <25 nmol/l] may be more common in populations with a higher proportion of at-risk groups, and/or that have low consumption of foods rich in vitamin D (naturally rich or fortified) and low use of vitamin D supplements. The definition of an adequate or optimal vitamin D status is key in determining recommendations for a vitamin D intake that will enable satisfactory status to be maintained all year round, including the winter months. In most European countries, there seems to be a shortfall in achieving current vitamin D recommendations. An exception is Finland, where dietary survey data indicate that recent national policies that include fortification and supplementation, coupled with a high habitual intake of oil-rich fish, have resulted in an increase in vitamin D intakes, but this may not be a suitable strategy for all European populations. The ongoing standardisation of measurements in vitamin D research will facilitate a stronger evidence base on which policies can be determined. These policies may include promotion of dietary recommendations, food fortification, vitamin D supplementation and judicious sun exposure, but should take into account national, cultural and dietary habits. For European nations with supplementation policies, it is important that relevant parties ensure satisfactory uptake of these particularly in the most vulnerable groups of the population.

Abstract: SUMMARY 1 INTRODUCTION 1.1 General structure of grains 1.2 Wheat 1.3 Rice 1.4 Maize 1.5 Barley 1.6 Oats 1.7 Rye 1.8 Millet 1.9 Sorghum 1.10 Triticale 1.11 Other grains 1.12 Key points 2TECHNICAL ASPECTS OF CEREALS 2.1 Cereal production 2.2 Storage 2.3 Processing 2.4 Cereals and food safety 2.5 Key points 3THE ROLE OF CEREALS IN HEALTH AND DISEASE 3.1 History of cereals in diet 3.2 Nutritional value of cereals 3.3 Contribution of cereals and cereal products in the diet 3.4 Cereals in health and disease 3.5 Labelling and health claims 3.6 Consumer understanding 3.7 Key points 4FUTURE DEVELOPMENTS 4.1 Fortification 4.2 Genetic modification 4.3 Gene–nutrient interactions 4.4 Key points 5CONCLUSIONS AND RECOMMENDATIONS REFERENCES GLOSSARY Summary Cereals are the edible seeds or grains of the grass family, Gramineae. A number of cereals are grown in different countries, including rye, oats, barley, maize, triticale, millet and sorghum. On a worldwide basis, wheat and rice are the most important crops, accounting for over 50% of the world's cereal production. All of the cereals share some structural similarities and consist of an embryo (or germ), which contains the genetic material for a new plant, and an endosperm, which is packed with starch grains. After harvest, correct storage of the grain is important to prevent mould spoilage, pest infestation and grain germination. If dry grains are held for only a few months, minimum nutritional changes will take place, but if the grains are held with a higher amount of moisture, the grain quality can deteriorate because of starch degradation by grain and microbial amylases (enzymes). Milling is the main process associated with cereals, although a range of other techniques are also used to produce a variety of products. Slightly different milling processes are used for the various grains, but the process can generally be described as grinding, sifting, separation and regrinding. The final nutrient content of a cereal after milling will depend on the extent to which the outer bran and aleurone layers are removed, as this is where the fibre, vitamins and minerals tend to be concentrated. There is potential for contamination of cereals and cereal products by pests, mycotoxins, rusts and smuts. Recently, acrylamide (described as a probable carcinogen) has been found in starchy baked foods. No link between acrylamide levels in food and cancer risk has been established and based on the evidence to date, the UK Food Standards Agency has advised the public not to change their diet or cooking methods. However, the Scientific Committee on Food of the European Union (EU) has endorsed recommendations made by Food and Agriculture Organisation/World Health Organization which include researching the possibility of reducing levels of acrylamide in food by changes in formulation and processing. Cereals have a long history of use by humans. Cereals are staple foods, and are important sources of nutrients in both developed and developing countries. Cereals and cereal products are an important source of energy, carbohydrate, protein and fibre, as well as containing a range of micronutrients such as vitamin E, some of the B vitamins, magnesium and zinc. In the UK, because of the mandatory fortification of some cereal products (e.g. white flour and therefore white bread) and the voluntary fortification of others (e.g. breakfast cereals), cereals also contribute significant amounts of calcium and iron. Cereals and cereal products may also contain a range of bioactive substances and there is growing interest in the potential health benefits these substances may provide. Further research is required in this area, including identification of other substances within cereals and their bioavailability. There is evidence to suggest that regular consumption of cereals, specifically wholegrains, may have a role in the prevention of chronic diseases such as coronary heart disease, diabetes and colorectal cancer. The exact mechanisms by which cereals convey beneficial effects on health are not clear. It is likely that a number of factors may be involved, e.g. their micronutrient content, their fibre content and/or their glycaemic index. As there may be a number of positive health effects associated with eating wholegrain cereals, encouraging their consumption seems a prudent public health approach. To increase consumption of wholegrain foods, it may be useful to have a quantitative recommendation. Additionally, a wider range of wholegrain foods that are quick and easy to prepare would help people increase their consumption of these foods. As cereal products currently contribute a considerable proportion of the sodium intake of the UK population, manufacturers need to continue to reduce the sodium content of foods such as breakfast cereals and breads where possible. Nutrition labelling is currently not mandatory in the UK, although many manufacturers provide information voluntarily. The fibre content of most UK foods is still measured using the Englyst method rather than the American Association of Analytical Chemists (AOAC) method used by other EU countries and the USA. However, UK recommendations for fibre intake currently relate to fibre measured by the Englyst method and not the AOAC method, and hence need revisions. EU changes to labelling regulations will see the labelling of common foods and ingredients causing allergic reactions, including cereals containing gluten and products derived from these foods. The introduction of EU legislation covering health claims may help consumers identify foods with proven health benefits. Several misconceptions exist among the public with regard to cereals and cereal products. Firstly, many more people believe they have a food intolerance or allergy to these foods than evidence would suggest and, secondly, cereals are seen by some as ‘fattening’. The public should not be encouraged to cut out whole food groups unnecessarily and, as cereals and cereal products provide a range of macro- and micronutrients and fibre, eliminating these foods without appropriate support and advice from a registered dietitian or other health professional could lead to problems in the long term. In the future it is possible that white flour in the UK may be fortified with folic acid (the synthetic form of the B vitamin folate) to decrease the incidence of neural tube defects during pregnancy. Such a move could also be of benefit for heart health, as poor folate status is associated with high homocysteine levels, an emerging risk factor for cardiovascular disease. However, high intakes of folic acid can mask vitamin B12 deficiency, a condition that occurs more frequently with age and has serious neurological symptoms affecting the peripheral nervous system. Manipulating the expression of native genes can increase the disease resistance of cereal crops. Novel genes may also be used for this purpose, as well as for developing cereals with resistance to herbicides, and cereals with improved nutritional properties (e.g. increased levels of iron in cereals and of beta-carotene in rice). The long-term consequences and consumer acceptability of such advances must be considered and consumer choice maintained. There is a continual growth in the knowledge of the interactions between human genes and nutrients, and in the future it may be possible to target specific nutrition messages to people with specific genetic profiles.

Abstract: Summary The health benefits of including sufficient dietary fibre in the diet have been well described and have formed the basis of dietary recommendations around the world However, dietary fibre is a complex dietary entity, consisting of many non-digestible components of food Debate surrounding the definition and measurement of dietary fibre has resulted in inconsistencies in labelling, description and recommendations set across the world In the UK, dietary recommendations are made using the fraction of non-digestible material described as non-starch polysaccharide that is measured by the Englyst method However, the Association of Official Analytical Chemists (AOAC) methods, used widely by the food industry, capture a much greater range of non-digestible material, that some suggest should be included in any definition of dietary fibre An attempt to resolve such discrepancies, possibly by taking an approach that considers the health effects of fractions not captured in the Englyst method, is probably overdue Additionally, it is clear that the effects of these various non-digestible components of dietary fibre are not interchangeable, and it is important that fibre comes from a range of sources to ensure maximum health benefits from the fibre in the diet Traditional ‘insoluble’ fibres are required to add bulk as well as rapidly fermentable, viscous fibres to bring about cholesterol lowering There is also a convincing argument for including slowly fermented components, such as resistant starches, that are well tolerated in the digestive system and can bring about improvements in gut function Currently there is insufficient data from well designed human intervention trials to make specific recommendations on the amounts of these fibre components in the diet, but it may be useful for health professionals to talk in terms of the different food sources of these types of fibre, as well as total fibre amounts