1. Charakterystyka żywności / składnika

Characterisation of the food/constituent (ID 744, 745, 746, 748, 749, 753, 803, 810, 855, 1415, 1416, 4308, 4330)
The food constituents that are the subject of this opinion are “dietary fibre”, “rich in dietary fibre” and “soluble fibre” related to the following claimed effects: satiety, weight management, normal blood glucose concentrations, normal blood cholesterol concentrations, normal bowel function and regularity, reduction of postprandial glycaemic response, decreasing potentially pathogenic gastro-intestinal microorganisms, increasing the number of gastrointestinal microorganisms, and fat absorption. Dietary fibre is the common name for all carbohydrate components occurring in foods that are non-digestible in the human small intestine. These components include non-starch polysaccharides, resistant starch, resistant oligosaccharides with three or more monomeric units, and other non-digestible, but quantitatively minor, components when naturally associated with dietary fibre polysaccharides, especially lignin. The terms “soluble” and “insoluble” have been used in the literature to classify dietary fibre as viscous soluble in water (e.g. pectins) or as water insoluble (e.g. cellulose) in an attempt to link different physical-chemical properties of fibre components to different physiological effects. However, the above classification is method-dependent, and water solubility does not always predict the physiological effects of dietary fibre (EFSA, 2007).
Total fibre and different types of fibre can be measured in foods by established methods. However, intake of dietary fibre has a number of physiological effects in humans. These effects can vary depending on the unique physical and chemical characteristics of the fibre component, in addition to the dose and mode of administration (EFSA, 2007).
The Panel refers to a previously published opinion on dietary fibre and the maintenance of normal blood cholesterol concentrations (EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA), 2009a). The Panel also refers to previously published opinions on the relationship between the consumption of various fibre components and different claimed effects (e.g. increase in satiety, maintenance or achievement of a normal body weight, reduction of post-prandial glycaemic responses, bowel function, and maintenance of normal blood glucose, blood cholesterol, and triglyceride concentrations). The outcomes of these latter assessments are variable and depend on the quality of the data provided and the type of fibre component being evaluated in relation to a certain claimed effect (EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA), 2009a, 2009b, 2009c, 2010a, 2010b, 2010c, 2010d, 2010e, 2010f).
Some of the references provided reported on the effects of dietary fibre on appetite ratings and occasionally on subsequent energy intake, which have been tested in many short term studies using a variety of fibres (e.g. guar gum, psyllium, pectin, β-glucan), fibre doses and food matrices (Wilmshurst and Crawley, 1980; Hoad et al., 2004; Delargy et al., 1995; Delargy et al., 1997; Tiwary et al., 1997; Kim et al., 2006) with variable results. Reasons for the discordant outcomes may stem from differing study designs and sample populations, but particularly relate to the types of fibre used in these studies and to their physico-chemical characteristics (“soluble” vs. “insoluble”, viscous vs. non-viscous) (Delargy et al., 1995; Slavin and Green, 2007).
A number of the references provided addressed the effects of mixed dietary fibre, of “soluble” vs. “insoluble” dietary fibre, or of specific types of fibre on post-prandial blood glucose responses. Results from these studies are mixed. Different types of fibre appear to have variable effects on post-prandial blood glucose (and insulin) responses in humans, and the same applies to fibre-rich meals (i.e. depending on the fibre source, food matrix, total fibre dose and amount of “soluble” vs. “insoluble” dietary fibre). Whereas some types of fibre and fibre-rich foods appear to decrease post-prandial blood glucose concentrations with variable effects on insulin responses, others do not affect post-prandial blood glucose responses (Frape and Jones, 1995; Juntunen et al., 2002; Ulmius et al., 2009; Papathanasopoulos and Camilleri, 2010).
The references provided which investigated the effects of dietary fibre on fat absorption in the gut reported different effects of different types of fibre on fat absorption. Fat absorption may be increased, decreased or not affected by fibre consumption (Baer et al., 1997; Sosulski and Cadden, 1982; Wolever et al., 1997).
The World Health Organization/Food and Agriculture Organization (WHO/FAO) report of 2003 on Diet, Nutrition and the Prevention of Chronic Diseases submitted in the consolidated list concluded that the available evidence for an effect of dietary fibre on body weight regulation and the prevention of obesity was convincing based on epidemiological evidence and the results from two meta-analyses of randomised controlled trials (RCT) assessing the effects of mixed, “soluble” and “insoluble” types of fibre on body weight compared to low-fibre diets both ad libitum and during energy restriction (Pereira and Ludwig, 2001; Howarth et al., 2001). However, different types of fibre have been shown to exert variable effects on body weight particularly when administered as food supplements in RCT, ranging from substantial to non significant weight loss compared to placebo (Pittler and Ernst, 2001 and 2004; Papathanasopoulos and Camilleri, 2010).
Two of the references provided reported on prospective cohort studies which addressed the association between dietary fibre intake and coronary heart disease (CHD) (Wolk et al., 1999; Pereira et al., 2004). In these studies, higher intakes of total dietary fibre have been associated with reduced incidence of coronary events and CHD mortality. This association was primarily owing to cereal fibre intakes (Wolk et al., 1999) or to cereal fibre and fruit fibre intakes (Pereira et al., 2004), suggesting that different types of fibre may have different effects on heart health.
A number of narrative reviews and intervention studies assessed the effects of different types of fibre (resistant starch, wheat bran, guar gum, cellulose, hemicellulose, inulin, oligosaccharides, etc.) and of fibre from different sources (carrot, cabbage, apple, flaxseeds, etc.) on faecal bulk. The references provided supported the notion that different types of fibre and fibre from different sources have widely variable bulking effects, which are also related to the amount of fibre consumed (Bianchi and Capurso, 2002; Flamm et al., 2001; Jenkins et al., 1986; Jenkins et al., 1998; Muir et al., 2004; Phillips et al., 1995; Roberfroid, 1993; Schneeman, 1999; Tarpila et al., 2005; Cummings et al., 1978).
The Panel considers that the food constituent, dietary fibre, which is the subject of this opinion, is not sufficiently characterised in relation to the claimed effects considered in this opinion.
The Panel concludes that a cause and effect relationship cannot be established between the consumption of dietary fibre and the claimed effects considered in this opinion.

Oświadczenia zdrowotne

ID 1416 - Rich in dietary fibre

1. Charakterystyka żywności / składnika

Warunki i możliwe ograniczenia stosowania oświadczenia