Toxicological evaluation of some food additives including anticaking agents, antimicrobials, antioxidants, emulsifiers and thickening agents WHO FOOD ADDITIVES SERIES NO. 5 The evaluations contained in this publication were prepared by the Joint FAO/WHO Expert Committee on Food Additives which met in Geneva, 25 June - 4 July 19731 World Health Organization Geneva 1974 1 Seventeenth Report of the Joint FAO/WHO Expert Committee on Food Additives, Wld Hlth Org. techn. Rep. Ser., 1974, No. 539; FAO Nutrition Meetings Report Series, 1974, No. 53. KARAYA GUM Explanation This substance has been evaluated for acceptable daily intake by the Joint FAO/WHO Expert Committee on Food Additives (see Annex 1, Ref. No. 19) in 1969. Since the previous evaluation, additional data have become available and are summarized and discussed in the following monograph. The previously published monograph has been revised and is reproduced in its entirety below. BIOLOGICAL DATA BIOCHEMICAL ASPECTS Karaya gum does not disintegrate appreciably in the alimentary tract. In a study of 10 dogs 95% of the orally administered gum was recovered in the faeces. It absorbs a large quantity of water and therefore acts as a mechanical laxative. It tends to increase faecal nitrogen excretion, does not affect starch digestion in the dog and does not inhibit the utilization of vitamin A in rats (Ivy & Isaacs, 1938). The caloric value was determined in groups of 10 rats fed for one week 5 g basal diet with either 1 g and 3 g corn starch or 1 g and 3 g karaya gum supplements. At the 1 g level karaya gum only had 30% of the caloric value of corn starch. At the 2 g level growth was very depressed. The intestines were enlarged in all rats on gum (Wisconsin Alumni Research Foundation Laboratory, 1964). TOXICOLOGICAL STUDIES Acute toxicity No data available. Short-term studies Rat Examination of the intestines of rats fed 1 g of karaya gum per day for 91 days showed no gross abnormalities. There was no interference with normal growth (Ivy & Isaacs, 1938). Dog Three dogs were fed 5 g unprocessed karaya daily for 30 days. Defaecations were more frequent, faecal bulk and moisture were increased but there was no obvious gastrointestinal irritation (Ivy & Isaacs, 1938). Long-term studies Rat Five rats were fed 20% karaya gum in the diet for two years. Three developed enlarged colon and ulceration (Hoelzel et al., 1941). In another experiment groups of three rats were fed karaya gum at first at 10%, gradually increasing to 25% in the diet over their life span. Controls of five and seven animals received low residue diets. No caecal ulceration was found in this experiment (Carlson & Hoelzel, 1948). OBSERVATIONS IN MAN Forty-six female and 43 male subjects took karaya gum granules for one week at levels equivalent to 7 g per day. Seven subjects had abdominal discomfort (Ivy & Isaacs, 1938). Ingestion or inhalation was reported to have caused allergy (Figley, 1950). Sixteen cases of allergic sensitivity to inhalation of the gum used as a wave set, and to oral ingestion as a laxative were reported. Symptoms included hay fever, asthma, dermatitis and gastrointestinal distress (Figley, 1950). In a comparison with carob bean gum as a laxative in 10 human subjects karaya gum was found to be transformed to a gelatinous state at a higher level in the intestine and to be transported more rapidly through the intestinal tract (Holbrook, 1951). Comments: Karaya gum has a long history of human use as a laxative agent and has also been consumed as food though being of less calorie value. There is evidence in a few species that the gum might irritate the bowel. In a few cases allergic responses in man have been recorded. The long-term tests reveal only enlargement of the colon but are inadequate. Metabolic studies in several species, preferably including man, and adequate 90-day studies in several species are required before an evaluation can be done. EVALUATION Not possible on the data available. REFERENCES Carlson, A. J. & Hoelzel, F. (1948) J. Nutr., 36, 27 Figley, K. D. (1950) J. Amer. med. Ass., 114, 747 Hoelzel, F., Costel, E. & Carlson, A. J. (1941) Amer. J. dig. Dis., 8, 266 Holbrook, A. A. (1951) Amer. J. dig. Dis., 18, 24 Ivy, A. C. & Isaacs, B. L. (1938) Amer. J. dig. Dis., 5, 315 Wisconsin Alumni Research Foundation Lab. (1964) Unpublished report No. 3110860/1 to Stein, Hall & Co.
See Also: Toxicological Abbreviations Karaya gum (FAO Nutrition Meetings Report Series 46a) Karaya gum (WHO Food Additives Series 18) Karaya gum (WHO Food Additives Series 24) KARAYA GUM (JECFA Evaluation)