ID 821 - Beta-glukany z jęczmienia

PL: Beta-glukany z jęczmienia
EN: Barley beta-glucan
Pdf: beta-glucans from oats

1. Charakterystyka żywności / składnika

The foods/food constituents that are the subject of the health claims are “barley grain fibre”, “oat grain fibre”, “oats beta-glucan”, “barley beta-glucan”, “barre céréalière diététique contenant de l'avoine”, and “oatbran and oatbran products”.
From the conditions of use and references provided, the Panel assumes that the food constituent responsible for the claimed effects is beta-glucans from oats and barley.
Beta-glucans are soluble cereal fibres. They are non-starch polysaccharides composed of glucose molecules in long linear glucose polymers with mixed β-(1→4) and β-(1→3) links with an approximate distribution of 30 % to 70 %. Their molecular weight varies from 50 to 2,000 kDa. Beta-glucans occur naturally in the bran of cereal grasses such as barley (~7 %), oats (~5 %), rye and wheat (1-2 %), and are measurable in foods by established methods. This opinion applies to beta- glucans naturally present in foods, and added to foods.
The mixed linkages are important for their physical properties, such as solubility and viscosity. Their viscosity is a function of the concentration of dissolved beta-glucans, and of their molecular weight (Wood et al., 2000), and further depends on differences in raw materials, processing and methods of determination.
The Panel considers that the food constituent, beta-glucans from oats and barley, which is the subject of the health claims, is sufficiently characterised.

2.3. Ograniczenie wzrostu stężenia glukozy (glikemii) po posiłku (ID 821, 824)

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 Panel assumes that the claimed effect refers 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 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). Decreasing post-prandial glycaemic responses may be beneficial to subjects with, for example, impaired glucose tolerance, as long as post-prandial insulinaemic responses are not disproportionally increased. Impaired glucose tolerance is common in the general adult population.
The Panel considers that the 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 821, 824)

The references provided for the scientific substantiation of the claim included publications on the health effects of dietary fibre in general, on the health effects of low glycaemic foods and/or diets, and on the effects of barley and/or oat products and/or beta-glucans on health outcomes unrelated to the claimed effect (e.g. blood lipids). The references also included human intervention studies which reported on measures of blood glucose in which the amount of beta-glucans consumed was not specified (Granfeldt et al., 1994; Liljeberg et al., 1992), or in which the study population was insulin-dependent or non-insulin dependent diabetic subjects on either insulin or oral hypoglycaemic medications (Braaten et al., 1994; Jenkins et al., 2002; Pick et al., 1996; Pick et al., 1998; Tappy et al., 1996). The evidence provided does not establish that results obtained in patient populations treated with anti-diabetic medications can be generalised to the target population with respect to post-prandial glycaemic responses. The Panel considers that no conclusions can be drawn from these references for the scientific substantiation of the claim.
Three human intervention studies investigated the effects of barley and/or oat beta-glucans on post- prandial glycaemic and insulinaemic responses in healthy subjects using a standardised meal protocol in which whole-meal bread products (from oats, barley, and rye) were compared to white wheat bread (Juntunen et al., 2002; Liljeberg et al., 1996; Östman et al., 2006). All of these studies had a randomised cross-over design with washout periods longer than three days, and sample sizes between 9 and 20 subjects (men and women). Two out of the three studies (Liljeberg et al., 1996; Östman et al., 2006) observed a statistically significant reduction in post-prandial glycaemic and insulinaemic responses following consumption of the test meals which included beta-glucan-containing products (from oats or barley), compared to the test meals not containing beta-glucans, at doses between 4.6-14 g beta-glucans per 30 g of available carbohydrates. The study by Juntunen et al. (2002) did not show a significant effect on post-prandial glycaemic responses of rye bread containing 5.4 g beta-glucans in 50 g of available carbohydrate compared to white wheat bread, whereas post-prandial insulinaemic responses were significantly reduced.
Two human intervention studies investigated the effects of incorporating oat (Holm et al., 1992) or barley (Yokoyama et al., 1997) beta-glucans into pasta products (control pasta made with plain durum wheat flour) in 10 and 5 healthy subjects, respectively. These studies had a randomised cross-over design with washout periods longer than three days. Consumption of pasta with 12 g of beta-glucans in a 100 g available carbohydrate portion (about 3.6 g/30 g available carbohydrates) resulted in significantly lower and delayed peak glucose responses, and in lower peak insulin responses
(Yokoyama et al., 1997), whereas enrichment with oat bran (28 %) giving 6 % beta-glucans in the final product only slightly decreased post-prandial insulinaemic responses, while post-prandial glycaemic responses were unchanged compared to the control pasta (Holm et al., 1992).
Another test meal study, which investigated the effects on post-prandial blood glucose and insulin responses of oat and barley beta-glucan products in healthy subjects, used a standardised protocol in which sucrose was used as a control (Behall et al., 2005). Ten overweight women (mean age 50.1±7.7 years; BMI 30.3±2.2 kg/m2) consumed glucose (1 g/kg body weight) and four test meals consisting of 0.33 g/kg body weight of carbohydrate from pudding (predominantly sucrose) plus 0.67 g/kg body weight of carbohydrates from oat flour, oatmeal, barley flour, or barley flakes to constitute a total of 1 g carbohydrates/kg body weight at breakfast after a 10 h fast. The content of beta-glucans in the test food grains was 4 and 15 g/100 g dry matter in the oat and barley test foods, respectively (about 1.8 and 6.5 g/30 g available carbohydrates, respectively). Blood samples were collected at fasting and every 30 min up to 180 min after the acute loads. Peak glucose and insulin concentrations after the barley test foods were significantly lower than those after the glucose or oat test foods. Post-prandial glucose responses (area under the curve) were significantly reduced after the consumption of oat and barley test foods when compared to sucrose. Post-prandial glucose responses after barley (flour and flakes) were significantly lower than the post-prandial glucose responses after oat (flour and oatmeal). Post-prandial insulinaemic responses were significantly reduced by barley test foods only (44-56 %, p<0.005). The content of beta-glucans in the barley test foods was almost four times higher than in the oat test foods, which could have explained the differential effects of the barley and oat test foods on post-prandial glucose and insulin responses.
The Panel notes that the studies above consistently show an effect of oat and barley beta-glucans in decreasing post-prandial glycaemic responses, without disproportionally increasing post-prandial insulinaemic responses, at doses of at least 4 g per 30 g of available carbohydrates.
The mechanism by which beta-glucans from oats or barley could exert the claimed effect is well established, and relates to the increased viscosity of the meal bolus when beta-glucans are added. When the meal bolus reaches the small intestine, a high viscosity delays the rate of absorption of nutrients, including glucose (Battilana et al., 2001; Wood et al., 2000; Wursch and Pi-Sunyer, 1997).
In weighing the evidence, the Panel took into account that intervention studies in healthy subjects consistently show an effect of oat and barley beta-glucans in decreasing post-prandial glycaemic responses, without disproportionally increasing post-prandial insulinaemic responses, at doses of about 4 g per 30 g of available carbohydrates in bread and pasta products when consumed alone or in the context of a meal, and that the mechanism by which beta-glucans could exert the claimed effect is well established.
The Panel concludes that a cause and effect relationship has been established between the consumption of beta-glucans from oats and barley and a reduction of post-prandial glycaemic responses.

4.1. Ograniczenie wzrostu stężenia glukozy (glikemii) po posiłku (ID 821, 824)

The Panel considers that the following wording reflects the scientific evidence: “Consumption of beta-glucans from oats or barley contributes to the reduction of the glucose rise after a meal”.

5.1. Zmniejszenie stężenia glukozy we krwi po posiłku (ID 821, 824)

In order to obtain the claimed effect, 4 g of beta-glucans from oats or barley for each 30 g of available carbohydrates should be consumed per meal. The target population is individuals who wish to reduce their post-prandial glycaemic responses.

Warunki i możliwe ograniczenia stosowania oświadczenia

Bakery products which contain beta-glucan of barley grain fibre ≥3g/daily serving Amount: 6g/100g of oat grain fibre Processing of the product may weaken the utilisation of beta-glucan in the body and its health impacts. Content, viscosity, solubility and molecular weight of beta-glucan in the products should be specified to be able to refer to the utilisation of the beta-glucan present in the product.