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.

    GUAR 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 expanded and is reproduced
    in its entirety below.

    BIOLOGICAL DATA

    BIOCHEMICAL ASPECTS

         The digestibility of guar gum in rats fed 0.4 g/day was estimated
    to be 76% (Booths et al., 1963). The rat can use guar gum as precursor
    for liver glycogen but at a much reduced efficiency (Krantz et al.,
    1948). Feeding chicks for four weeks on a diet containing 3%
    cholesterol, 3% guar gum and 3% cholesterol plus 3% 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 (Wisconsin Alumni Research Foundation
    Laboratory, 1964).

    TOXICOLOGICAL STUDIES

    Acute toxicity

         No data available.

    Short-term studies

    Rat

         Five male rats were fed 0 and 5% 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% 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 5% 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 were carried to termination at 104 weeks. There were no
    adverse effects on growth, and gross and microscopic pathology
    (Krantz, 1947).

         A 90-day feeding study with groups of 10 male and 10 female rats
    at levels of 0, 1, 2 and 5% is in progress (Til & Spanjers, 1973).

    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).

    Chicken

         Groups of 20 chicks, one-day-old, maintained on diets containing
    2% guar gum for 21 days showed depressed growth, reduced nitrogen
    retention, fat absorption. Pancreatic weight was significantly
    increased when diets contained guar gum in a high protein (30%) diet
    (Kratzer et al., 1967).

    Long-term studies

         None available.

    OBSERVATIONS IN MAN

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

    Comments:

         Guar gum is consumed in some parts of the world as a component of
    guar flour. When it comprises less than 15% of the diet it is
    calorically equivalent to corn starch. A short-term and a long-term
    study in rats, though both not adequate by present standards, revealed
    no adverse effects at the 5% level. A new adequate short-term study is
    under way to check the reliability of the older studies. Further work
    would be desirable on the potential effects of macromolecules storage
    in the body.

    EVALUATION

    Estimate of acceptable daily intake for man

         Not limited.*

    FURTHER WORK OR INFORMATION

    Desirable

         Results on the short-term study which is in progress to check the
    reliability of the older studies.

    REFERENCES

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

    Couch, J. 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

    Kratzer, F. H., Rajaguru, R. W. A. S. B. & Vohra, P. (1967) Poultry
         Sci., 46(6), 1489-1493

    Til, H. P. & Spanjer, M. T. H. (1973) Report No. 4093, TNO

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

              

    *    See relevant paragraph in the seventeenth report, pages 10-11.

    See Also:
       Toxicological Abbreviations
       Guar gum (FAO Nutrition Meetings Report Series 46a)
       GUAR GUM (JECFA Evaluation)