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.
ISOASCORBIC ACID AND ITS SODIUM SALT
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. 6) in 1961.
The previously published monograph has been revised and is
reproduced in its entirety below.
BIOLOGICAL DATA
BIOCHEMICAL ASPECTS
Isoascorbic acid is readily absorbed and metabolized. Following
an oral dose of 500 mg of isoascorbic acid to human subjects the blood
level curves for ascorbic acid and isoascorbic acid showed a similar
rise. In five human subjects, an oral dose of 300 mg was shown to have
no effect on the urinary excretion of ascorbic acid (Kadin & Osadca,
1959). Isoascorbic acid was found to have no antagonistic effect on
the action of ascorbic acid (Gould, 1948).
TOXICOLOGICAL STUDIES
Acute toxicity
No information available.
Short-term studies
Rat
Groups of 10 male rats were fed for 36 weeks on diets containing
1% of isoascorbic acid, and on diets without isoascorbic acid. There
was no difference between the treated rats and the controls with
respect to rate of growth and mortality. Gross post mortem examination
and microscopic studies of various organs revealed no lesion
attributable to isoascorbic acid (Fitzhugh & Nelson, 1946).
Long-term studies
Rat
Groups of rats were fed on diets containing 1% of isoascorbic
acid and diets without isoascorbic acid for two years. The growth
rate, mortality, and histopathology were not affected by the treatment
(Lehman et al., 1951).
Comments:
There are adequate short and long-term studies in the rat. The
biochemical studies indicate that isoascorbic acid is readily
metabolized and does not affect the urinary excretion of ascorbic
acid.
EVALUATION
Level causing no toxicological effect
Rat: 10 000 ppm (1%) in the diet equivalent to 500 mg/kg bw.
Estimate of acceptable daily intake for man
0-5 mg/kg bw.
REFERENCES
Fitzhugh, O. G. & Nelson, A. A. (1946) Proc. Soc. exp. Biol., 61, 195
Gould, D. S. (1948) Arch. Biochem., 19, 1
Kadin, H. & Osadca, M. (1959) J. Agric. Food Chem., 7, 358
Lehman, A. J. et al. (1951) Advanc. Food Res., 3, 197