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.


    GUAR GUM

    This polysaccharide consists mainly of galacto mannans.

    Biological Data

    Biochemical aspects

    The digestibility of guar gum in rats fed 0.4 g/day was estimated to
    be 76 per cent. (Booths et al., 1963). The rat can use guar gum as a
    precursor for liver glycogen but at a much reduced efficiency (Krantz
    et. al., 1948). Feeding chicks for four weeks on a diet containing
    three per cent. cholesterol, three per cent. guar gum and three per
    cent. cholesterol plus three per cent. guar gum reduced the serum
    cholesterol levels, especially if both cholesterol and guar gum were
    ingested. Liver cholesterol was only depressed if cholesterol and guar
    gum were fed (Couch et al., 1966). The caloric value was determined in
    groups of 10 rats fed for one week a 5 g basal diet supplemented with
    either 1 g or 3 g corn starch or 1 g and 3 g guar gum. At 1 g level
    guar gum was equivalent to corn starch but at the 3 g level there was
    a lower equivalence. All animals had large intestines but normal
    faeces (Warf, 1964).

    Acute toxicity

    No data available.

    Short-term studies

    Rat. Five male rats were fed 0 and five per cent. guar gum for 91
    days in their diet. No differences were observed between the two
    groups in weight gain and food efficiency (Booths et al., 1963). Five
    rats were fed a diet containing 0.5 per cent. guar gum and varying
    amounts of water. Weight gain and protein efficiency increased with
    higher water content (Keane et al., 1962).

    Fifteen male and 15 female rats were fed a diet containing five per
    cent,of guar flour. Thirty rats served as control. Animals were
    sacrificed for autopsy studies at two to three month intervals. Seven
    male and eight female animals remained at 50 weeks. The experiment was
    continued, but the final report is not available to WHO. Up to 50
    weeks, growth histopathology of liver and kidney were similar in the
    treated and the control groups (Krantz, 1947).

    Monkey. Two monkeys (no duration animals) received 1 g of guar flour
    in their diet per day. Wellbeing, growth and haematology (RBC, WBC, HP
    and urea N2) remained normal (Krantz, 1947).

    Man.  Five volunteers ingested 1 g of guar flour in a capsule per
    day for 10 days without any apparent effect (Krantz, 1947).

    Long-term studies

    None available.

    Comments

    Guar gum is consumed in some parts of the world as a component of guar
    flour. When it comprises less than 15 per cent. of the diet it is
    calorically equivalent to corn starch. The metabolic fate in animals
    and man is not known.  Only inadequate animal tests are available but
    a long-term study in rats is in progress.

    EVALUATION

    Level causing no toxicological effects in the rat

    Five per cent. (= 50 000 ppm) in the diet equivalent to 2500 mg/kg
    body weight/day.

    Estimate of acceptable daily intake for man

                                            mg/kg body weight

    Temporary acceptance                         0-125

    Further work required by June 1972

    Metabolic studies in several species and an adequate 90-day study in a
    non-rodent mammalian species.

    REFERENCES

    Booths, A. N., Hendrickson, A. P. & De Eds, F. (1963) Toxic appl.
    Pharmacd., 5, 478

    Couch, L R., Bakski, Y. K. & Farr, F. M. (1966) VII International
    Congress of Nutrition, Abstracts, p. 195

    Keane, K. W. et al. (1962) J. Nutr., 77, 18

    Krantz, J. C. (1947) Unpublished report by General Mills, Inc.

    Krantz, J. C., Carr, C. J. & Farson, C. B. (1948) J. Amer. diet.
    Ass., 24, 212

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

    See Also:
       Toxicological Abbreviations
       Guar gum (WHO Food Additives Series 5)
       GUAR GUM (JECFA Evaluation)