ID 794 -
Guma guar
PL: Guma guar
EN: Cyamopsis tetragonolobus (Guar)
Pdf: Cyamopsis tetragonoloba
Oświadczenie (2)
- wpływ na poziom glukozy we krwi / kontroli glikemii / glikemii odpowiedzi
1. Charakterystyka żywności / składnika
The food constituent that is the subject of the health claims is guar gum. Guar gum is a water-soluble type of fibre, a galactomannan composed of a backbone of D-mannose units with D-galactose attached at every second mannose unit. It is derived from the cluster bean (Cyamopsis tetragonoloba (L.) Taub.). Guar gum is non-digestible in the human small intestine. The molecular weight is about
220 kDa. Guar gum is not naturally occurring in foods and is usually consumed in the form of food supplements. Guar gum has a high viscosity, it is used as a thickener by the food industry, and can be measured in foods by established methods.
The Panel considers that the food constituent, guar gum, which is the subject of the health claims is sufficiently characterised.
2.1. Utrzymanie prawidłowego stężenia glukozy we krwi (ID 794)
The claimed effect is “impact on blood glucose/glycaemic control/glycaemic response”. The Panel assumes that the target population is the general population.
In the context of the proposed wordings, the Panel assumes that the claimed effect refers to long-term maintenance or achievement of normal blood glucose concentrations.
The Panel considers that long-term maintenance of normal blood glucose concentrations is a beneficial physiological effect.
3.1. Utrzymanie prawidłowego stężenia glukozy we krwi (ID 794)
The references provided include intervention studies and reviews on the health effects of specific fibres other than guar gum (e.g. partially hydrolysed guar gum), on the effects of guar gum on health outcomes unrelated to blood glucose control (e.g. blood lipids), or were opinions from authoritative bodies not specifically addressing the effects of guar gum on long-term blood glucose control. The Panel considers that no scientific conclusions can be drawn from these references for the substantiation of the claim.
Among the references provided including measures of blood glucose control, two (Kovacs et al., 2002a and 2002b) describe the test product as “modified” guar gum. The Panel is uncertain on how the “modified” guar gum relates to the food which is the subject of the health claim but assumes that any modification to structure could affect function in relation to the claimed effect and therefore these references were not considered pertinent to the claim.
A number of references on the effects of guar gum 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 constituent on long-term maintenance or achievement of normal blood glucose concentrations in the general population. Also, a number of studies investigating the acute effects (after a single administration) of guar gum consumption 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 long-term maintenance or achievement of normal blood glucose concentrations.
Only four of the studies cited investigated the long-term effects of guar gum consumption on measures of blood glucose (Beattie et al., 1988; Lalor et al., 1990; Makkonen et al., 1993; Uusitupa et al., 1984).
Three of the studies (Lalor et al. 1990; Makkonen et al., 1993; Uusitupa et al., 1984) assessed the effects of guar gum at doses between 7.5 g/d and 22.5 g/d for periods of six weeks to six months on fasting blood glucose concentrations in different population sub-groups (i.e., type 2 diabetic subjects on dietary treatment only, non-diabetic post-menopausal women). The Panel notes that the doses of guar gum used in these studies are several times higher than proposed in the conditions of use for this claim, and that fasting blood glucose concentrations alone are not an appropriate measure to assess long-term blood glucose control. The Panel considers that no scientific conclusions can be drawn from these studies in relation to long-term maintenance or achievement of normal blood glucose concentrations.
In a study by Beattie et al. (1988) 24 newly diagnosed overweight type 2 diabetics were randomised to one of three treatment groups. One group received a low fibre (15 g fibre) control diet throughout the 20-week study period. The second group received the control diet for four weeks before changing to a high cereal diet (same macronutrient content but supplemented with an additional 10-15 g of cereal fibre) for eight weeks after which they returned to the control diet supplemented with 15 g/d guar gum for eight weeks. The third group received the control diet for four weeks, the guar gum diet for eight weeks and the high cereal fibre diet for eight weeks. Samples of venous blood were taken every two weeks for measurement of fasting plasma glucose and glycated haemoglobin. Whilst the reduction in plasma blood glucose concentrations during the two high fibre diets was greater than during the low fibre diet at the end of the first eight weeks of the trial, this difference was not significant after 20 weeks. No differences were observed between groups in values of glycated haemoglobin at any time point during the intervention. The Panel notes the small number of subjects included in this study and that the daily doses of guar gum used are eight times higher than proposed in the conditions of use.
In weighing the evidence, the Panel took into account that the only study presented investigated the long-term effects of guar gum on fasting blood glucose and glycated haemoglobin, the latter being an appropriate measure to assess long-term blood glucose control, and found no effect of guar gum consumption at doses eight times higher than proposed in the conditions of use.
The Panel concludes that a cause and effect relationship has not been established between the consumption of guar gum and long-term maintenance of normal blood glucose concentrations.
Warunki i możliwe ograniczenia stosowania oświadczenia
Single dose of 1.8 g/day