JECFA recognises gum Arabic as food additive that can be used with no ADI specified, which is the safest category allocarted by them. 

In the USA it is accorded GRAS (Generally Regarded as Safe), recoded in th US Food Chemical Codex under the number 18411330.

Here the efforts which have been undertaken to ensure the full safety status of Acacia senegal and Acacia seyal

There is a very rigorous system used by JECFA to evaluate the safety of food additives. Although some national jurisdictions do distinguish between “natural”, “nature-identical” and “artificial” or “synthetic” food additives, international committees such as the Joint FAO/WHO Expert Committee on Food Additives (JECFA) or the Scientific Committee for Food of the European Commission (SCF) do not. It might be considered that, for some natural materials, like acacia gum, there is evidence of safety-in-use derived from a long history of use by humans and, indeed, JECFA have indicated that when available, good quality human data should take precedence over animal data (WHO, 1987). However, scientifically verifiable human data on level of intake and safety-in-use may be rather scant. In many countries where such natural additives have been used, no long-term epidemiological studies have been conducted, and public health and mortality statistics may not be adequate for the purpose. It follows that such traditional uses rarely allow for a priori assumptions of safety. As a consequence, acacia gum has been subjected to the same rigorous toxicological testing and safety evaluation as any food additive.

Safety evaluation of acacia gum

Against the above background, it is of interest to consider the available database and the conclusions reached by the JECFA (which is advisory to the Codex Alimentarius Committee on Food Additives and Contaminants). Acacia gum (Gum Arabic) has been reviewed several times by the JECFA, firstly in 1969 then again in 1982 (WHO 1970;1982). Following the 1982 evaluation, a comprehensive toxicological monograph was produced. A further evaluation was conducted in 1989 when some further data were available, and a toxicological monograph addendum was produced (WHO 1990). The details of the database available are outlined below.

Metabolism and Pharmacokinetics

Based on food and caloric intake in rats and guinea pigs, at dietary levels of up to and above 10% the gum was virtually completely digested and utilised.

Acute toxicity

Although not a major factor in the safety evaluation, the acute toxicity of acacia has been evaluated in the mouse rat, hamster and rabbit and was shown to have a very low acute toxicity. The median lethal dose (LD50) was in the range 8 – 18 g/kg body weight as a bolus dose, equivalent to between 500g and 1kg for a 60kg adult human; clearly not relevant to the circumstances of human exposure.

Sub-acute/sub-chronic toxicity

Again short-term tests showed acacia gum to be practically devoid of toxicity at doses up to 10% of the diet in mice and rats, 15% of the diet in guinea pigs and 20% in rabbits. There were no gross nor microscopic lesions detected and just small effects on body weight gain which was reduced in mice at rats at the highest dose levels but increased in guinea pigs and rabbits.

Genotoxicity

The chemical structure and hydrophilicity of acacia gum are such that no genotoxic effects would be expected. Nevertheless, genotoxicity studies have been conducted in a number of bacterial and yeast strains in vitro, in Drosophila and in a dominant lethal assay in rats. These tests confirmed the lack of genotoxicity of acacia gum.

Chronic toxicity/Carcinogenicity

Long-term tests of two years duration have been conducted in both rats and mice at dietary levels of up to 5%. No increase in tumour incidence was observed and there were no other signs of chronic toxicity confirming the safety of the material on prolonged exposure.

Developmental studies

Teratology studies were conducted in rats, mice, hamsters and rabbits and were consistently negative. Some adverse maternal effects were reported in the rabbit at high dose levels of 173 or 800 mg/kg body weight but the dosing was by gavage (gastric stomach tube) as single bolus doses daily and this protocol commonly causes gastrointestinal dysfunction in rabbits.

 
Evaluation for an ADI

In evaluating the above data, which are quite comprehensive for a material of this type, the JECFA concluded that these data indicated that acacia gum had a very low toxicity and allocated an “ADI not specified” in 1982, confirmed in 1989 (WHO 1982; 1990). This is a commonly misunderstood end-point and it is useful to note the definition, which was included as a footnote to the toxicological monograph.

The statement “ADI not specified” means that, on the basis of the available data (toxicological, biochemical and other) the total daily intake of the substance arising from its use or uses at the levels necessary to achieve the desired effect, and from its acceptable background in food does not…represent a hazard to health. For this reason…the establishment of an ADI in mg/kg body weight is not deemed necessary.

Review of Specifications

Since the toxicological evaluation was conducted, a number of questions concerning source species and specifications have arisen. As a consequence the specifications were revised at the 44th meeting of the JECFA in 1995 (WHO, 1995; FAO 1995). This clarified that gum acacia referred to material derived from Acacia senegal and related species such as Acacia seyal. The committee considered that acacia gum meeting the revised specifications adequately reflected the material that was tested toxicologically and it was not necessary, therefore, to conduct a further toxicological evaluation. At the 51st meeting in 1998, the specifications were again revised but the original conclusion that material complying with the revised specifications was adequately covered in the toxicological evaluation was confirmed (WHO 2000).

Conclusions

Acacia gum has been subjected to a rigorous and remarkably thorough toxicological evaluation and no significant adverse effects have been observed even at very high doses. Accordingly, the JECFA have concluded that a numerically limited ADI was unnecessary and allocated an “ADI-not-specified”. Foreseeable intakes would not be considered to present any appreciable risk to health

References

FAO (1995) Compendium of food additive specifications, addendum 3 FAO Food and Nutrition Paper No. 52. Add.3. Rome: FAO.

WHO (1982) WHO Food Additives Series No.17. Toxicological Evaluation of Certain Food Additives. Twenty-sixth report of the Joint FAO/WHO Expert Committee on Food Additives. Geneva:WHO

WHO (1987) Environmental Health Criteria No. 70. Principles for the Safety Assessment of Food Additives and Contaminants in Food Geneva: WHO

WHO (1990) WHO Food Additives Series No.26. Toxicological Evaluation of Certain Food Additives and Contaminants. Prepared by the thirty-fifth meeting of the Joint FAO/WHO Expert Committee on Food Additives. Geneva: WH

WHO (1995) WHO Technical Report Series 859. Evaluation of Certain Food Additives and Contaminants. Forty-fourth report of the Joint FAO/WHO Expert Committee on Food Additives. Geneva:WHO

WHO (2000) WHO Technical Report Series 891. Evaluation of Certain Food Additives and Contaminants. Fifty-first report of the Joint FAO/WHO Expert Committee on Food Additives. Geneva:WHO