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.

    SALTS OF MYRISTIC, PALMITIC, AND STEARIC ACIDS

    Explanation

         These compounds have been evaluated for acceptable daily intake
    by the Joint FAO/WHO Expert Committee on Food Additives (see Annex 1,
    Ref. No. 20) 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

         Myristic, palmitic and stearic acid are the naturally occurring
    fatty acid component of tallow and other animal fats and oils as well
    as some vegetable oils. Most of the commercial and pharmaceutical
    preparations also contain mixed acids. Myristic acid has been shown to
    decrease the incorporation of acetyl Co-A into fatty acids by liver
    homogenates (Korchak & Masoro, 1964). Giving 1-C14 labelled stearic
    acid to two groups of four male rats resulted in the formation of
    labelled cholesterol which was widely distributed within 24 hours
    after administration (De Leo & Foti, 1961). Diets containing 20 to 40%
    glycerylmonostearate depress the growth and cause high mortality in
    young and adult mice. This is preventable by 4% oleate or linoleate.
    Depot fat levels of stearate do not increase. The mechanism of
    toxicity is unknown (Tove, 1964). Stearic acid is only 24% digestible
    as measured by fat ingested and excreted in male rats fed seven to
    eight days 10% of stearic acid in their diet (Carroll & Richards,
    1958). Stearic acid decreases the incorporation of acetyl Co-A into
    fatty acids by liver homogenate fractions (Korchak & Masoro, 1964).

         Using 14C-labelled palmitic acid i.v. in rats it was shown that
    30% entered the liver within five minutes where it was present almost
    wholly in the esterified form. More 14C appeared in the hepatic
    neutral fats than in the phospholipid fraction and it disappeared more
    rapidly from neutral fat. Similar relations were found for plasma
    fats. After 80 minutes the levels of 14C in plasma and liver lipids
    were similar, however the carcass lipids were not equilibrated even
    after 24 hours (Olivecrona, 1962). The in vitro uptake of tritium-
    labelled palmitic acid by the lipid fraction of rat pancreas was not
    affected by non-opmoc detergents, but was increased by cationic and
    anionic detergents. Only anionic lauryl sulfate stimulated the
    incorporation into neutral lipids of palmitic acid but not into the
    phospholipid fraction (Oett, 1965).

    Comments:

         Myristic, palmitic and stearic acid and their salts are normal
    products of the metabolism of fats and their metabolic fate is well
    established. Provided the contribution of the cations does not add
    excessively to the normal body load there is no need to consider the
    use of these substances in any different light to that of dietary
    fatty acids.

    EVALUATION

    Estimate of acceptable daily intake for man

         Not limited.*

    REFERENCES

    Carroll, K. K. & Richards, J. F. (1958) J. Nutr., 64, 411

    De Leo, T. & Foti, L. (1961) Drugs affecting lipid metabolism Proc.
         Symp., Milan, pp. 83-88

    Korchak, H. M. & Masoro, E. J. (1964) Biochim. biophy. Acta., 84, 750

    Oett, K. (1965) Experientia, 21, 253

    Olivecrona, T. (1962) Acta physiol, scand., 54, 295

    Tove, S. B. (1964) J. Nutr., 84, 237

              

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

    See Also:
       Toxicological Abbreviations