INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY

    WORLD HEALTH ORGANIZATION



    TOXICOLOGICAL EVALUATION OF SOME
    FOOD COLOURS, EMULSIFIERS, STABILIZERS,
    ANTI-CAKING AGENTS AND CERTAIN
    OTHER SUBSTANCES



    FAO Nutrition Meetings Report Series 
    No. 46A WHO/FOOD ADD/70.36




    The content of this document is the result of the deliberations of the
    Joint FAO/WHO Expert Committee on Food Additives which met in Rome,
    27 May - 4 June 19691





    Food and Agriculture Organization of the United Nations

    World Health Organization



                   
    1 Thirteenth report of the Joint FAO/WHO Expert Committee on Food
    Additives, FAO Nutrition Meetings Report Series, in press;
    Wld Hlth Org. techn.  Rep. Ser., in press.


    KARAYA GUM

    Biological Data

    Biochemical aspects

    Karaya gum does not disintegrate appreciably in the alimentary tract.
    In a study of 10 dogs 95 per cent. 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
    per cent. 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
    (Warf, 1964).

    Acute toxicity

    No data available.

    Short-term studios

    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 gastro-intestinal irritation (Ivy &
    Isaacs, 1938).

    Man. Fifty subjects ate 4-6 g Karaya gum in ice-cream. No allergic
    reactions were noted (Herzberg, 1963). 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 gastro-intestinal
    distress (Figley, 1940).

    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).

    Long-term studies

    Rat. Five rats were fed 20 per cent. 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 per cent., gradually increasing to 25 per cent. 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).

    Comments

    Karaya gum has a long history of human use as a laxative agent. 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.
    Special attention might be paid to determining the frequency of
    allergic reactions when a product is used that conforms to these
    specifications.

    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. & Isaaas, B. L. (1938) Amer. J. dig. Dis., 5, 315

    Wisconsin Alumni Research Foundation Lab. (1964) Unpublished report
    No. 3110860/1 to Stein, Hall and Co.
    

    See Also:
       Toxicological Abbreviations
       Karaya gum (WHO Food Additives Series 5)
       Karaya gum (WHO Food Additives Series 18)
       Karaya gum (WHO Food Additives Series 24)
       KARAYA GUM (JECFA Evaluation)