ID 830 -
Arabinoksylan z kiełków pszenicy
PL: Arabinoksylan z kiełków pszenicy
EN: Wheat grain fibre
Pdf: arabinoxylan produced from wheat endosperm
1. Charakterystyka żywności / składnika
The food constituent that is the subject of the health claim is “wheat grain fibre”.
From the references and information provided, the Panel assumes that the food constituent that is responsible for the claimed effect is arabinoxylan from wheat endosperm, which is a soluble and viscous fibre produced during the commercial processing of wheat flour.
Arabinoxylans are polysaccharides with a backbone of 1,4-linked xylose units with 2, 3, or 2,3-linked arabinose side chains, which can be found in many cereal grains and which may have different chemical properties depending on the source and the part of the grain used. Arabinoxylans also contain large amounts of ferulic acid and other phenolic compounds covalently linked to them.
Arabinoxylan (AX) represents 60-69 % of non-starch polysaccharides (NSPs) in wheat bran (mostly insoluble), and about 88 % of NSPs in wheat endosperm (more water soluble).
The Panel considers that the food constituent, arabinoxylan produced from wheat endosperm, which is the subject of the health claim, is sufficiently characterised in relation to the claimed effect.
2. Znaczenie oświadczenia dla zdrowia człowieka
The claimed effect is “carbohydrate metabolism and insulin sensitivity”. The Panel assumes that the target population is individuals who wish to reduce their post-prandial glycaemic responses.
In the context of the proposed wordings, the references submitted and the clarifications provided by Member States, the Panel assumes that the claimed effect refers to the reduction of post-prandial glycaemic responses.
Post-prandial glycaemia is interpreted as the elevation of blood glucose concentrations after consumption of a food and/or meal. This function is a normal physiological response that varies in magnitude and duration, and which may be influenced by the chemical and physical nature of the food or meal consumed, as well as by individual factors (Venn and Green, 2007). Reducing post-prandial blood glucose responses may be beneficial to subjects with impaired glucose tolerance as long as
post-prandial insulinaemic responses are not disproportionally increased. Impaired glucose tolerance is common in the general population of adults.
The Panel considers that reduction of post-prandial glycaemic responses (as long as post-prandial insulinaemic responses are not disproportionally increased) may be a beneficial physiological effect.
3. Naukowe uzasadnienia wpływu na zdrowie człowieka - Zmniejszenie stężenia glukozy we krwi (glikemii) po posiłku
The references provided for the scientific substantiation of the claim included narrative reviews, observational and human intervention studies on various health effects of dietary fibre or cereal fibre in general, or on the effects of wheat fibre on health outcomes (e.g. bowel function and markers of inflammation) unrelated to the claimed effect. The Panel considers that no conclusions can be drawn from these references for the scientific substantiation of the claim.
Three intervention studies investigated the effects of AX consumption on post-prandial blood glucose and insulin responses (Lu et al., 2000; 2004; Möhlig et al., 2005).
In one sequential study by Möhlig et al. (2005), 15 volunteers (9 female) first consumed a control breakfast without AX. During the second visit, a breakfast with 6 g of AX-enriched fibre was administered. The Panel notes that the order of the intervention and control breakfasts was not randomised in this study, and that therefore the study was uncontrolled for time effects. The Panel considers that no conclusions can be drawn from this uncontrolled study for the scientific substantiation of the claim.
In the study by Lu et al. (2000), the effects of three breads containing 0, 6 or 12 g of AX-rich fibre (i.e. extracted from the by-products of wheat flour processing) on induced post-prandial glycaemic and insulinaemic responses were investigated in 14 subjects (9 female) with normal glucose tolerance using a randomised cross-over design. The breads were consumed in the context of a standard breakfast (10 g protein, 14 g fat) containing 75 g of available carbohydrates (50 g starch from bread,
25 g sugars from jam). All subjects received the three test breakfasts on a single occasion 3 days apart. The AX-rich fibre contained 70 % NSPs by weight, with a soluble:total NSP ratio of 0.62, an AX:total NSP ratio of 0.90 and an arabinose:xylose ratio of 0.60. Blood glucose and insulin concentrations were measured at baseline and 15, 30, 45, 60, 75, 90 and 120 min after each breakfast. A repeated-measures general linear model using time, meal type, and time and meal type interaction as within-subject factors was used to compare the effects of breakfast meals containing different amounts of AX-rich fibre at different time points over 2 h post-prandial. Differences in incremental areas under the curve (iAUCs) for glucose and insulin responses, as well as dose-response relationships, were also assessed. Fasting plasma glucose did not differ between the three interventions. Blood glucose concentrations peaked at 30 min after consumption of the meals, and peak post-prandial glucose concentrations after the meals containing 6 and 12 g of AX-rich fibre were significantly lower than after the control meal (p<0.01 and p<0.001, respectively). No significant differences were observed between meals containing 6 and 12 g of AX-rich fibre. Fasting plasma insulin did not differ between the three interventions and insulin concentrations peaked at 30 min after consumption of the three meals. Differences in blood insulin concentrations did not differ significantly between meals except for the 12 g of AX-rich fibre vs. the control meal at 45 min post- prandial (p<0.001). The iAUC for glucose was significantly lower during the 6 g AX-rich fibre meal than during the control meal (-20.2 %, p<0.05), and significantly lower during the 12 g AX-rich fibre meal than during the 6 g AX-rich fibre meal (p<0.05) and the control meal (-41.4 %, p<0.01). The iAUC for insulin was significantly lower during the 6 g AX-rich fibre meal (-17.0 %, p<0.05) and that during the 12 g AX-rich fibre meal (-32.7 %, p<0.001) than during the control meal. No significant differences were observed between the 6 g and the 12 g AX-rich fibre meals with respect to iAUC for insulin. A significant inverse relationship was observed between the amount of AX-rich fibre in meals and the mean iAUC for glucose (r2= -0.989, p=0.033) and for insulin (r2= -0.999, p=0.008). The Panel
notes that this study shows a dose-dependant effect of AX-rich fibre on the reduction of post-prandial glycaemic responses without disproportionally increasing post-prandial insulinaemic responses.
Lu et al. (2004) designed a randomised, single-blinded (subjects blinded), controlled cross-over study to assess the effects of an AX-rich fibre of the same characteristics as in the study by Lu et al. (2000) on blood glucose control in 15 subjects (9 women) with type II diabetes. Ten subjects were treated with diet only, five were on low-dose oral hypoglycaemic medications and none required insulin for blood glucose control. Two subjects were on lipid-lowering medications and nine on antihypertensive medications. No changes in medication use or dose were recorded during the study. Subjects consumed control muffins and bread (50 % whole wheat and 50 % white flour) and AX-rich muffins and bread (50 % whole wheat, 36 % white flour and 14 % AX-rich fibre) in the context of their usual diet for five weeks each with no wash-out period in between. The AX-rich foods provided 14-17 g of NSPs (of which 90 % was AX) daily compared to the control foods. Plasma glucose and insulin were assessed in fasting and at 2 hours after a 75 g oral glucose tolerance test (OGTT), both at baseline and after each study phase. Plasma concentrations of fructosamine as a surrogate marker of blood glucose control were also measured. Differences between the two arms of the cross-over design were evaluated using a General Linear Model (GLM) for cross-over designs. The sequence in which the intervention and control diets were administered had no effect on the outcome variables. Fasting plasma glucose concentrations were significantly lower after the AX-rich diet than after the control diet (p<0.05). No significant differences between groups were observed with respect to fasting insulin concentrations. The 2 h glucose and insulin concentrations after the OGTT and after fructosamine concentrations were significantly lower after the AX-rich diet than after the control diet (p<0.001, p=0.015, and p=0.02, respectively). Post-hoc power calculations using the data obtained in the study and α=0.05 indicated a power of 0.98 and 0.99 for fasting and 2 h glucose concentrations, respectively, but only of 0.57 for fructosamine. The Panel notes that although post-prandial glycaemic and insulinaemic responses following AX consumption were not measured directly in this study, the results are consistent with an effect of AX on the reduction of post-prandial glycaemic responses, as observed in the study by Lu et al. (2000).
The mechanism by which soluble fibres (including AX produced from wheat endosperm) could exert the claimed effect is well established, and relates to the increased viscosity of the meal bolus, which delays the rate of absorption of nutrients (including glucose) in the small intestine.
In weighing the evidence, the Panel took into account that one well-designed intervention study in healthy subjects showed a dose-response relationship between the intake of AX produced from wheat endosperm and reduction in post-prandial glycaemic and insulinaemic responses, that the results obtained in a longer term intervention study, which did not measure directly post-prandial glycaemic responses, were consistent with this finding, and that the mechanism by which AX produced from wheat endosperm could exert the claimed effect is well established.
The Panel concludes that a cause and effect relationship has been established between the consumption of arabinoxylan produced from wheat endosperm and reduction of post-prandial glycaemic responses.
4. Uwagi do zaproponowanego brzmienia oświadczenia
The Panel considers that the following wording reflects the scientific evidence: “Consumption of arabinoxylan contributes to a reduction of the glucose rise after a meal”.
5. Warunki i możliwe ograniczenia stosowania oświadczenia
The Panel considers that in order to obtain the claimed effect, 8 g of AX-rich fibre produced from wheat endosperm (at least 60 % AX by weight) per 100 g of available carbohydrates should be
consumed. The target population is individuals who wish to reduce their post-prandial glycaemic responses.
Warunki i możliwe ograniczenia stosowania oświadczenia
Bakery products with ≥6g/100g of wheat grain fibre
