ID 826 - Błonnik z żyta

PL: Błonnik z żyta
EN: Rye fibre
Pdf: rye fibre

1. Charakterystyka żywności / składnika

The food constituent that is the subject of the health claims is rye fibre.
The rye (Secale cereale L.) fibre is predominantly composed of non-starch polysaccharides. The main components of the non-starch polysaccharides in whole grain rye are arabinoxylan (8-12 %), fructan (4.6-6 %), beta-glucan (1.3-2.2 %) and cellulose (1.0-1.7 %) (Kamal-Eldin et al., 2009). More than 80 % of rye fibre is insoluble. Beta-glucan and arabinoxylan are the soluble types of fibre in rye.
Rye bran products may differ with regard to chemical composition and particle size depending on the milling process.
The Panel considers that the food constituent, rye fibre, which is the subject of the health claims, is sufficiently characterised in relation to the claimed effects.

2.2. Ograniczenie wzrostu stężenia glukozy (glikemii) po posiłku (ID 826)

The claimed effect is “carbohydrate metabolism and insulin sensitivity”. The Panel assumes that the target population is individuals wishing to reduce their post-prandial glycaemic responses.
In the context of the proposed wordings, the Panel assumes that the claimed effect relates to the reduction of post-prandial glycaemic responses.
Postprandial 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 which 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, for example, 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 a reduction of post-prandial glycaemic responses (as long as post-prandial insulinaemic responses are not disproportionally increased) may be a beneficial physiological effect.

3.2. Ograniczenie wzrostu stężenia glukozy (glikemii) po posiłku (ID 826)

The references provided for the substantiation of the claim included one human intervention study which reported on health outcomes other than the claimed effect (e.g. bowel function); human intervention studies conducted in insulin-dependent diabetic patients or in ileostomy patients with ulcerative colitis; human intervention studies on post-prandial glycaemic and insulinaemic responses
to whole foods in which either the amount of rye fibre was not reported or a certain amount of rye fibre in bread was compared to the same amount of, for example, wheat fibre, and thus did not allow conclusions to be made on the effects of rye fibre per se; and human intervention studies in healthy subjects which did not assess post-prandial blood glucose responses following consumption of rye fibre, but rather the effects of longer-term consumption of rye fibre-containing food products on glucose tolerance (i.e. using the frequently sampled intravenous glucose tolerance test or the oral glucose tolerance test). The Panel considers that no conclusions can be drawn from these references for the scientific substantiation of the claim.
Three intervention studies provided investigated the effects of rye fibre in rye products on post- prandial blood glucose and insulin responses (Juntunen et al., 2002; Juntunen et al., 2003; Leinonen et al., 1999).
In the study by Leinonen et al. (1999), the effects of wheat bread (61 g available carbohydrates; 2.3 g fibre), whole kernel rye bread (55 g available carbohydrates; 13.5 g fibre), wholemeal rye bread (43 g available carbohydrates; 10.1 g fibre) and wholemeal rye crispbread (45 g available carbohydrates; 12.1 g fibre) consumed with a standard breakfast were compared with respect to induced post-prandial glucose and insulin responses (measured every 30 min for three hours, and at 15 min post-prandial) in 20 subjects (10 female) with normal glucose tolerance using a randomised cross-over design. Direct comparisons were made between wheat bread and whole kernel rye bread (two types of cereals), and between wholemeal rye bread and wholemeal rye crispbread (two types of rye bread). The Panel considers that only the first comparison is appropriate for the scientific substantiation of the claim. No significant differences in post-prandial blood glucose responses at any time point, or measured as areas under the curve, were observed between wheat bread and whole kernel rye bread. Insulin concentrations were significantly lower at 45 (p=0.025), 60 (p=0.002), 90 (p=0.0004), 120 (p=0.05) and 150 (p=0.033) min after the whole kernel rye bread than after the wheat bread (p=0.002 for the area under the curve). The Panel notes that this study did not show an effect of rye fibre on post- prandial glycaemic responses.
In the study by Juntunen et al. (2002), the effects of wheat bread made from white wheat flour (3.1 g fibre), whole kernel rye bread (12.8 g fibre), wholemeal pasta (5.6 g fibre) and wholemeal rye bread containing oat beta-glucan concentrate (17.1 g fibre) were compared with respect to induced post-prandial glucose and insulin responses (measured every 30 min for three hours and at 15 min post-prandial) using a randomised cross-over design and standard portions containing 50 g of available carbohydrates for all test foods. Subjects were 20 healthy men and women (mean age 28±1 years; BMI 22.9±0.7 kg/m2). The Panel notes that wholemeal rye bread containing oat beta- glucan concentrate cannot be used to address the effects of rye fibre, and that wheat bread is more appropriate than pasta to test the effects of rye fibre in whole kernel rye bread on post-prandial blood glucose responses. No significant differences in post-prandial blood glucose responses at any time point, or measured as areas under the curve, were observed between wheat bread and whole kernel rye bread. A significant decrease in post-prandial insulinaemic responses was observed after consumption of the whole kernel rye bread compared to the wheat bread (p<0.05). The Panel notes that this study did not show an effect of rye fibre on post-prandial glycaemic responses.
In the study by Juntunen et al. (2003) the effects of wheat bread made from white wheat flour (2.7 g fibre), endosperm rye bread (6.1 g fibre), traditional rye bread (15.2 g fibre) and high-fibre rye bread (29.0 g fibre) were compared with respect to induced post-prandial glucose and insulin responses (measured every 30 min for three hours, and at 15 min post-prandial) using a randomised cross-over design and standard portions containing 50 g of available carbohydrates for all test foods in a random order. Subjects were 19 healthy post-menopausal women aged 61±1 years and with a BMI of 26.0±0.6 kg/m2. No differences in post-prandial blood glucose responses (measured as maximal response or as incremental areas under the curve) were observed between wheat bread and the different rye breads. A significant decrease in post-prandial insulinaemic responses was observed
after consumption of the endosperm rye bread and the traditional rye bread compared to the wheat bread (p<0.05). No significant difference was observed between the high-fibre rye bread and the wheat bread. The Panel notes that this study did not show an effect of rye fibre on the reduction of post-prandial glycaemic responses. In weighing the evidence, the Panel took into account that the three human intervention studies provided from which conclusions could be drawn for the scientific substantiation of the claim did not show an effect of rye fibre on post-prandial glycaemic responses.
The Panel concludes that a cause and effect relationship has not been established between the consumption of rye fibre and reduction of post-prandial glycaemic responses.

Warunki i możliwe ograniczenia stosowania oświadczenia

Coarse rye flour with 14g/100g of fibre, 8g/dl (serving) Rye flakes with 13g/100g of fibre, 3.9g/dl (serving) Rye bran with 39g/100g of fibre, 1.2-1.6g/tbs (serving) Coarse particles slow down absorption.