Toxicological evaluation of some food colours, thickening
    agents, and certain other substancse


    The evaluations contained in this publication were prepared
    by the Joint FAO/WHO Expert Committee on Food Additives which
    met in Geneva, 14-23 April 19751

    World Health Organization, Geneva 1975

    1 Nineteenth Report of the Joint FAO/WHO Expert Committee on Food
    Additives, Wld Hlth Org. techn. Rep. Ser., 1975, No. 576;
    FAO Nutrition Meetings Report Series, 1975, No. 55.

    The monographs contained in the present volume are
    also issued by the Food and Agriculture Organization
    of the United Nations, Rome, as
    FAO Nutrition Meetings Report Series, No. 55A

    ISBN 92 4 166008 2

    (C) FAO and WHO 1975




         This substance was evaluated for acceptable daily intake for man
    by the Joint FAO/WHO Expert Committee on Food Additives (see Annex 1,
    Refs No. 20 and No. 33) in 1969 and 1973.

         Since the previous evaluation, additional data have become
    available and are summarized and discussed in the following monograph.
    The previously published monographs have been expanded and are
    reproduced in their entirety below.



         The principal component of this gum is a galactomannan with
    a linear chain of (1 -> 4) linked ß-D-mannopyranose units with
    alpha-D-galactopyranose units attached by (1 -> 6) linkages to every
    fourth or fifth mannose. In a bioavailable calorie assay groups of
    10 male weanling rats (Sprague-Dawley) were given 5 g basal diet or
    plus 0.5, 1, 2 g sucrose or 0.5, 1, 2 g gum for 10 days. Comparison of
    the carcass weight gain showed that carob bean gum was not a source of
    bioavailable calories (Robaislek, 1974). Fifteen controls and 18 male
    test rats, after three days on normal diet followed by a 12 hour fast,
    received two-and-one-half days in their diet either 67% cocoa butter
    with wheat flour or 67% cocoa butter with 33% carob bean gum. Glycogen
    accumulated in the liver but far less efficiently than with wheat
    flour (Krantz et al., 1948). A digestibility study in groups of five
    male and five female rats (Purdue strain) on a mannose-free diet
    showed that 85-100% of mannose fed as 1% carob bean gum in the diet
    for 18 hours were excreted in the faeces over a total of 30 hours.
    Some decrease in chain length of galactomannan may have occurred
    probably through the action of the microflora as mammals are not known
    to possess mannosidase. Liberation of galactose units was not
    determined (Tsai & Whistler, 1975). Incubation of solutions or
    suspensions with human gastric juice, duodenal juice + bile,
    pancreatic juice and succus entericus with or without added rabbit
    small gut membrane enzymes produced no evidence of hydrolysis
    (Semenza, 1975). Rat large gut microflora partially hydrolyzed carob
    bean gum in vitro (Towle & Schranz, 1975) after conditioning to
    1% carob bean gum in the diet for three weeks. Groups each of eight
    male Holtzman rats were maintained on a purified synthetic diet, or
    the diet plus 1% cholesterol, or the diet + 1% cholesterol + 10% carob
    bean gum for 28 days. The increased liver cholesterol and liver total
    lipid induced by cholesterol feeding was largely counteracted by
    concurrent feeding of carob bean gum (Ershoff & Wells, 1962).


    Special studies on teratogenicity

         Teratological experiments with four species of animals (rats,
    mice, hamsters and rabbits) did not indicate that the test material
    was a teratogen to mice at 280 mg/kg body weight and 1300 mg/kg
    although 5/21 dams died at the latter dose. Up to 1300 mg/kg in rats,
    up to 1000 mg/kg in hamsters and at 196 mg/kg in rabbits no
    teratological effects were seen. At 910 mg/kg in rabbits most of the
    pregnant dams died (Morgareidge, 1972).

    Special studies on mutagenicity

         Mutagenic tests on rats and mice using three different methods
    gave negative results. There was no measurable mutagenic response in
    recombination frequency for Sacch. cerev. in host-mediated assay at
    5 g/kg or in vitro. No adverse effects were seen on chromosomes in
    rat bone marrow or human lung cell cultures. The dominant lethal test
    in rats was negative (Maxwell & Newell, 1972).

    Acute toxicity

                              LD50              Reference
    Species     Route    mg/kg body weight

    Rat         Oral         >5 000             Maxwell & Newell, 1972

    Short-term studies


         Groups of 10 males and 10 females were fed in their diet carob
    bean gum at levels of 0%, 1%, 2% or 5% for 90 days. General condition,
    behaviour, survival, growth, food intake, haematology, blood
    biochemistry and urinalysis showed no treatment-related differences
    between test and control groups at any dietary level except that the
    blood glucose level was slightly increased in the 5% group. Gross and
    microscopic examination did not reveal any pathological changes
    attributable to ingestion of the gum. The increase in the relative
    weight of the caecum at the 2% and 5% levels is not considered to be
    of toxicological importance (Til et al., 1974).


         Groups of 20-day-old chicks were fed diets containing 0.25%,
    0.5%, 1% and 2% carob bean grain for three weeks. Growth depression
    was dose related and marked at the 2% level of intake (Kratzer et al.,
    1967; Vohra & Kratzer, 1964).


         Four groups of five male and five female beagles were fed 0%,
    1%, 5% or 10% of a precooked mixture of carob bean and guar gum
    (proportions unknown) for 30 weeks. Only at the 10% level were
    hypermotility and soft, bulky stools observed, probably of no
    toxicological significance. Also at the 10% level digestibility
    was reduced. No adverse haematological, urinary, gross and
    histopathological and ophthalmological findings were noted (Cox
    et al., 1974).


         A clinical study of a commercial preparation of carob bean grain
    as a laxative in doses of "two heaping teaspoonfuls" in 56 patients,
    some of whom took the preparation regularly for two years, resulted in
    no untoward effects related to the gastro-intestinal tract, and no
    allergenic reaction (Holbrook, 1951).

         Eight infants between the ages of 2.5-5 months were fed meals of
    sugared milk or sugared milk plus a 1% powder extracted from carob
    bean. Addition of the carob supplement did not alter the duration of
    the gastro-intestinal transit time of the meal. Physiological
    aerophagy was markedly suppressed by the supplement (Rivier, 1952).


         In vitro tests with human enzyme preparations show little
    utilization by the gut. The available short-term studies in the rat
    and dog showed no evidence of adverse effects at the 5% level. Carob
    bean gum is used in pharmaceutical preparations. No long-term or
    reproduction studies are available but no teratogenic or mutagenic
    potential has been found.


    Estimate of acceptable daily intake for man

         Acceptable daily intake not specified.1*


    Required by 1980.

    (1)  An adequate long-term study in a rodent species.

    (2)  Reproduction studies.


    Cox, G. E., Baily, D. E. & Morgareidge, K. (1974) Subacute feeding in
         dogs with a pre-cooked gum blend. Unpublished report from the
         Food and Drugs Labs, Inc. submitted to the World Health
         Organization by Hercules BV

    Ershoff, B. H. & Wells, A. F. (1962) Effects of Gum Guar, Locust Bean
         Gum and Carrageenan on Liver Cholesterol of Cholesterol-Fed Rats,
         Proc. Soc. exp. biol. med., 110, (3), 580-582

    Holbrook, A. A. (1951) The behaviour of carob bean in the
         gastrointestinal tract of man, A. J. Dig. Dis., 18, 24-28

    Krantz, J. C., jr, Carr, C. J. and de Farson, C. B. (1948) Guar poly
         saccharide as a precursor of glycogen, J. Amer. diet Ass.,
         24, 212

    Kretzev, F. H., Rajaguru, R. W. A. S. B. & Vohra, P. (1967) The effect
         of polysaccharides on energy utilization, nitrogen retention and
         fat absorption in chickens, Poultry Sci., 48, 1489-1493


    1    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, in the opinion of the Committee,
    represent a hazard to health. For this reason, and for the reasons
    stated in individual evaluations, the establishment of an acceptable
    daily intake (ADI) in mg/kg bw is not deemed necessary.

    *      Temporary.

    Maxwell, W. A. & Newell, G. W. (1972) Study of the mutagenic effects
         of FDA-71-14 (Locust bean gum). Unpublished report from the
         Stanford Research Institute submitted to the World Health
         Organization by Hercules BV

    Morgareidge, K. (1972) Teratological evaluation of FDA-71-14 (Carob
         bean gum). Unpublished report from the Food and Drug Research
         Labs, Inc. submitted to the World Health Organization by Hercules

    Rivier, C. (1952) Recherches sur le mode d'action du Nestargel,
         Schweiz. Mediz. Wchsch., 82, 256

    Robaislek, E. (1974) Bioavailable calorie assay of Guar gum.
         Unpublished report from WARF Institute, Inc. submitted to the
         World Health Organization by Institut Européen des Industries de
         la Gomme de Caroube

    Semenza, G. (1975) Report on the possible digestion of locust bean gum
         in the stomach and/or in the small intestine in an in vitro
         study. Unpublished report from the Eidgenössische Technische
         Hochschule Zürich submitted to the World Health Organization by
         the Institut Européen des Industries de la Gomme de Caroube

    Til, H. P., Spanjers, M. Th. & de Groot, A. P. (1974) Sub-chronic
         toxicity study with locust bean gum in rats. Unpublished report
         from Centraal Instituut voor Voedingsonderzoek TNO submitted to
         the World Health Organization by Hercules BV and Institut
         Européen des Industries de la Gomme de Caroube

    Towle, G. A. & Schranz, R. E. (1975) The action of rat microflora on
         carob bean gum solutions in vitro. Unpublished report from
         Hercules Research Center submitted to the World Health
         Organization by Hercules Incorporated

    Tsay, L. B. & Whistler, R. L. (1975) Digestibility of galactomannans.
         Unpublished report submitted to the World Health Organization by
         Professor H. Neukom, Chairman of the Technical Committee of Inst.
         Europ. des Industries de la Gomme de Caroube

    Vohra, P. & Kratzer, F. H. (1964) Growth inhibitory effect of certain
         polysaccharides for chickens, Poultry Sci., 43, 1164-1170

    See Also:
       Toxicological Abbreviations