GUM ARABIC

    1.  EXPLANATION

         Gum arabic, also known as gum acacia, is the dried gummy exudate
    from tropical and subtropical  Acacia senegal trees.  The exudate is
    a proteinaceous polysaccharide, the protein content ranging from
    ca.1.5% to 3% for samples from different producing areas.  The
    proteinaceous components of eight bulk commercial gum arabic samples,
    and for eleven gum specimens secured from  Acacia senegal trees show
    that their amino acid compositions vary considerably, particularly
    with respect to the three major components (hydroxyproline, serine and
    proline), although the proportions of other amino acids (e.g.,
    alanine, cysteine, isoleucine, methionine, threonine, tyrosine and
    valine) are remarkably constant (Anderson  et al.,1985).  Gum arabic
    consists of several high-molecular-weight polysaccharides and their
    salts, which on hydrolysis yield arabinose, galactose, rhamnose and
    glucoronic acid (Anderson  et al., 1983).

         This substance was last evaluated for acceptable daily intake for
    humans by the Joint FAO/WHO Expert Committee on Food Additives in 1982
    (Annex 1, reference 59) when a toxicological monograph was prepared
    and an ADI "not specified" was allocated.

         Additional data have become available and are summarized and
    discussed in the following monograph addendum.

    2.  BIOLOGICAL DATA

    2.1  Biochemical aspects

         Groups of three male rats (140-160 g) were given diets containing
    0, (control), 1, 4 and 8% (w/w) of gum arabic for 28 days.  At autopsy
    (following macroscopical examination of all organs), materials for
    electron microscopy and for microsomal P-450 assays were secured from
    all animals. There were no detectable abnormalities in any of the
    organelles in the heart and liver specimens from any of the test
    animals and no inclusions nor other pathological changes were
    observed.  In addition, the data indicated that gum arabic did not
    induce cytochrome P-450 or microsomal protein (Anderson  et al.,
    1984).

    2.2  TOXICOLOGICAL STUDIES

    2.2.1  Special studies on teratogenicity

    2.2.2.1   Rats

         Twenty male and female Osborne-Mendel (FDA strain) rats,
    approximately 4 weeks old, were fed gum arabic  ad libitum in their
    diet at 0, 1, 2, 4, 7.5 or 15% for 13 weeks before mating.  The
    animals continued to eat the control or test diet throughout mating
    and gestation.  After mating was confirmed, the females were placed in
    groups of 41-47 animals.  During gestation, the treated females
    consumed from 683 mg gum/kg bw/day in the 1% group to 10,647 mg gum/kg
    bw/day in the 15% group.  There were no treatment-related changes in
    maternal findings, number of fetuses, fetal viability or external,
    visceral or skeletal variations and no terata were seen (Collins
     et al., 1987).

    3.  COMMENTS AND EVALUATION

         Further findings from teratology and biochemical studies were
    reviewed.  It was concluded that the results of these studies did not
    modify the previous evaluation.  The Committee confirmed the ADI "not
    specified".

    Estimate of acceptable daily intake

         ADI "not specified".  This term is applicable to a food substance
    of very low toxicity which, on the basis of the available data
    (chemical, biochemical, toxicological, and other), the total dietary
    intake of the substance arising from its use at the levels necessary
    to achieve the desired effect and from its acceptable background in
    food does not, in the opinion of JECFA, represent a hazard to health. 
    For that reason, and for reasons stated in individual evaluations, the
    establishment of an acceptable daily intake expressed in numerical
    form is not deemed necessary.  An additive meeting this criterion must
    be used within the bounds of good manufacturing practice, i.e., it
    should be technologically efficacious and should be used at the lowest
    level necessary to achieve this effect, it should not conceal inferior
    food quality or adulteration, and it should not create a nutritional
    imbalance.

    4.  REFERENCES

    ANDERSON, D.M.W., BRIDGEMAN, M.M.E., FARQUHAR, J.G.K. & McNAB, C.G.A.
    (1983).  The chemical characterization of the test article used in
    toxicological studies of gum arabic (Acacia senegal (L.) Willd). 
     Int. Tree Crops J. 21, 145-254.

    ANDERSON, D.M.W., ASHBY, P., BUSUTTIL, B., KEMPSON, S.A. & LAWSON,
    M.E. (1984).  Transmission electron microscopy of heart and liver
    tissues from rats fed with gum arabic and tragacanth.  Toxicology
     Letters, 21, 83-89.

    ANDERSON, D.M.W., HOWLETT, J.F. & McNAB, C.G.A. (1985).  The aminoacid
    composition proteinaceous component of gum arabic (Acacia senegal
    (L.) Willd).  Food Additives and Contaminants, 2, 159-164.

    COLLINS, T.F.X., WELSH, J.J., BLACK, T.N., GRAHAM, S.L. & BROWN, L.H.
    (1987). Study of the teratogenic potential of gum arabic.
     Fd.Chem.Toxic. 25, 815-821.

    See Also:
       Toxicological Abbreviations
       GUM ARABIC (JECFA Evaluation)