Chapter 3: Status of carbohydrates and dietary fibre in the gluten-free diet
Coeliac disease is one of the most common food intolerances worldwide and at present the gluten free diet remains the only suitable treatment. Since the life-long avoidance of this cereal protein means a major change to the diet, it is important to consider its effect on the nutritional status of adhering individuals. This study reviews the available publications on the total carbohydrate as well as the fibre intake of coeliac disease patients compared to that of the non-coeliac general public. In addition, 95 gluten free breads currently available on the market have been purchased and evaluated with regard to their nutritional value. Several fibre enriched gluten free breads are available on the market. This leaves the responsibility to the consumer to choose nutritionally valuable products. In conclusion it can be said that the dietary fibre intake in coeliac patients, as well as the general public is below recommendations.
Coeliac disease is an immune-mediated enteropathy triggered by the ingestion of the cereal protein gluten, present in wheat, rye and barley. Since life-long avoidance of gluten is currently the only treatment for coeliac disease, it is important to consider the effect of such a gluten free diet on nutrient intake and nutritional status of adhering patients. Concerns have been raised over the long term dietary habits and food choices of individuals on a strict gluten free diet, as a result from a number of studies indicating unbalanced intake of carbohydrates, proteins, and fat, as well as limited intake of certain essential nutrients in coeliac patients (Lohiniemi et al. 2000; Thompson et al. 2005). One highly important nutrient, repeatedly shown not to be consumed in sufficient amounts, is dietary fibre. Even though adherence to a gluten free diet might also lead to an insufficient consumption of other nutrients such as
calcium or certain vitamins, this review focuses on carbohydrate, sugar and fibre consumption in coeliac patients as well as on the content of these macronutrients in commercially available products. According to the European Food Safety Authority (EFSA) the intake of total carbohydrates - including starch and simple carbohydrates such as sugars - should range from 45 to 60% of total energy intake for both adults and children. Insufficient evidence was found to set an upper limit for sugars. This is because the possible health effects are mainly related to patterns of food consumption – i.e. the types of foods consumed and how often they are consumed – rather than to the total intake of sugars itself (Ruxton et al. 2010; Anderson et al. 2009). Although dietary fibres are in terms of chemical structure also carbohydrates, they are per definition not included in this macronutrient group, but stated separately on the nutrition label. The European Commission defines fiber as carbohydrate polymers with three or more monomeric units, which are neither digested nor absorbed in the human small intestine and belong to the following categories: edible carbohydrate polymers naturally occurring in the food as consumed; edible carbohydrate polymers which have been obtained from food raw material by physical, enzymatic or chemical means and which have a beneficial physiological effect demonstrated by generally accepted scientific evidence; edible synthetic carbohydrate polymers which have a beneficial physiological effect demonstrated by generally accepted scientific evidence (The Commission of the European Communities 2008). Dietary fibre generally falls into the two categories soluble and insoluble. The most soluble dietary fibres are more rapidly fermented in the colon and they are more accessible to hydrolytic enzymes; whereas the less soluble fibres are excreted in the stool and thus have the effect of increasing faecal bulk. EFSA as well as the Food and Drug Administration (FDA) recommend a daily total dietary fibre intake of 25 g per day, of which 6 g should be soluble fibre. The role of dietary fibre in contributing to a healthy intestine has long been recognised. Potential health benefits of dietary fibre include, reduction of bowel transit time, prevention of constipation, reduction in risk of colorectal cancer, lowering of blood cholesterol, production of short chain fatty acids
and promotion of the growth of beneficial gut microflora (Brennan and Cleary 2005). From a technological point of view, fibre addition can modify texture and sensory characteristic as well as prolong shelf-life, due to their water binding capacity, gel forming potential, fat mimetic properties and thickening effects (Sabanis et al. 2009; Thebaudin et al. 1997). One important source of dietary fibre is cereals, contributing to about 50% of the fibre intake in western countries (Nyman et al. 1989). In the gluten free diet, the consumed cereal products are considerably different to the gluten containing foods of this category, which might influence their nutritional quality. Several studies show that the dietary fibre intake of coeliac patients is too low (Grehn et al. 2001; Lee et al. 2009; Lohiniemi et al. 2000; Mariani et al. 1998; Öhlund et al. 2010; Thompson et al. 2005). It was proposed that this is due to the fact that gluten free breads are very often made from starches and/or refined flours and that these products are rarely enriched with fibres (Thompson 2000). Therefore they might contain less fibre than their gluten containing counterparts. The purpose of this study was to evaluate gluten free breads currently available on the market. For this purpose, 95 gluten free breads have been purchased in supermarkets and health shops of 7 European countries (France, Ireland, Italy, Finland, Germany, Austria, and Sweden) as well as the United States of America. Their nutritional value regarding intake of calories, carbohydrates and sugar as well as dietary fibre content, as stated on the packaging, was summarised and compared.