ID 802 - Beta-glukany

PL: Beta-glukany
EN: Beta-glucan
Pdf: various food(s)/food constituent(s)

Oświadczenie (2)

1. Charakterystyka żywności / składnika

The food constituent that is the subject of the health claim is beta-glucans soluble fibre of cereals. Beta-glucans 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 70% to 30%. The molecular weight varies between 50 and 2000 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 those forms added to foods.
The mixed linkages are important for the physical properties of beta-glucans, such as solubility and viscosity. The viscosity is a function of the concentration of dissolved beta-glucans and of its 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, which is the subject of the health claim is sufficiently characterised.

2. Znaczenie oświadczenia dla zdrowia człowieka

The claimed effect is “contribution to the maintenance of healthy blood glucose levels”. The Panel assumes that the target population is the general population.
In the context of the proposed wording, the Panel assumes that the claimed effect refers to the long- term maintenance or achievement of normal blood glucose concentrations.
The Panel considers that long-term maintenance or achievement of normal blood glucose concentrations is a beneficial physiological effect.

3. Naukowe uzasadnienia wpływu na zdrowie człowieka - Osiągnięcie i długotrwałe utrzymanie prawidłowego stężenia glukozy we krwi

A total of 50 publications (excluding duplicates) were cited in relation to the proposed claim. Some of the references report on the health effects of dietary fibre in general, on the health effects of low glycaemic foods and/or diets, or on the effects of barley and/or oat products and/or beta-glucans on health outcomes unrelated to blood glucose control (e.g. blood lipids). The Panel considers that no scientific conclusions can be drawn from these studies for the substantiation of the claimed effect.
A number of references on the effects of (oat/barley) beta-glucans on different outcomes in relation to blood glucose control were presented in insulin-dependent or non-insulin dependent diabetic subjects on either insulin or oral anti-diabetic therapy. The Panel considers that the evidence provided in these
studies does not predict the occurrence of an effect of the food(s)/constituent(s) on the long-term maintenance or achievement of normal blood glucose concentrations in the general population. Also, a number of studies investigating the effects of (oat/barley) beta-glucans on post-prandial glycaemic and/or insulinaemic responses were presented. The Panel considers that no scientific conclusions can be drawn from these studies in relation to the long-term maintenance or achievement of normal blood glucose concentrations.
In a study by Biörklund et al. (2005), 100 healthy subjects with mildly elevated blood cholesterol concentrations were randomised to consume either a control beverage (rice starch) or a beverage containing either 5 g or 10 g of either oat or barley beta-glucans (4 intervention arms) for 5 weeks after a 3-week run-in period in which all subjects consumed the control beverage. Fasting blood glucose and insulin were measured at the beginning and at the end of the intervention. No significant differences were observed between groups (intervention and control) in relation to changes on either fasting glucose or insulin concentrations.
Two studies addressed the effects of beta-glucans consumption for 4-5 weeks on glucose tolerance assessed by an oral glucose tolerance test (OGTT).
In the study by Li et al. (2003), 10 healthy Japanese women received a standard diet and a barley diet (with 1.8 g barley/kg body weight per day) for 4 weeks following a randomised cross-over design. The whole grain barley contained 45% barley bran with no measurement of beta-glucans content. No differences were observed between diet regimens after 4 weeks of intervention in relation to changes in fasting plasma glucose, in the area under the curve of blood glucose concentrations after an oral glucose tolerance test, or in blood glycated haemoglobin.
In a cross-over study by Hallfrisch et al. (1995), 23 overweight subjects (16 women) aged 38-61 years with mildly elevated blood cholesterol concentrations received a standard diet (equilibrium diet, run- in period) for 7 days. Then they were randomised to consume, alternatively, two identical menus where 5% of the fat energy was replaced with 5% carbohydrate energy with an oat extract containing either 1% or 10% soluble beta-glucans contributing between 0.8 and 1.2 g beta-glucans/MJ/d and between 5.1 and 7.7 g beta-glucans/d, respectively, for 5 weeks each. At the end of the run-in diet (baseline of the intervention with the oat extract), glycaemic and insulinaemic responses to an oral glucose tolerance test (1g glucose/kg body weight) were assessed. At the end of the intervention period (5 weeks), the oral glucose tolerance test was repeated; the test provided 2/3 of the carbohydrate dose (1 g/kg body weight) as glucose and 1/3 as the respective oat extract the subject was consuming during the testing period (1% or 10%). The Panel notes that the study was uncontrolled and that the test foods at the beginning and the end of the intervention were not comparable with regards to the amount of available carbohydrate or to their glycaemic properties. The Panel considers that no conclusions can be drawn form this study for the substantiation of the claimed effect.
In weighing the evidence the Panel took into account that the only two studies presented from which conclusions could be drawn for the substantiation of the claim (Biörklund et al., 2005; Li et al., 2003) showed no effect of beta-glucans consumption on the long-term maintenance or achievement of normal blood glucose concentrations.
The Panel concludes that a cause and effect relationship has not been established between the consumption of beta-glucans and the long-term maintenance or achievement of normal blood glucose concentrations.

Warunki i możliwe ograniczenia stosowania oświadczenia

7.5 grams of Nutrim® Oat Bran per serving provides 0.75 grams of beta-glucan oat soluble fiber 30 grams of Nutrim® Oat Bran per day provides 3 grams of beta-glucan oat soluble fiber Oat Beta Glucan Soluble Fiber = 10% Insoluble Fiber = 16% Total Dietary Fiber = 26%