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.
ACETIC AND FATTY ACID ESTERS OF GLYCEROL
Explanation
These emulsifiers have been evaluated for acceptable daily intake
by the Joint FAO/WHO Expert Committee on Food Additives (see Annex 1,
Ref. No. 13) in 1966.
The previously published monograph has been revised and is
reproduced in its entirety below.
BIOLOGICAL DATA
BIOCHEMICAL ASPECTS
The long-chain fatty acids in triglycerides may be replaced with
one or more acetic acid groups to produce mono- or diacetins
(acetoglycerides) which are resistant to changes in consistency, heat
damage and oxidative rancidity (Alfin-Slater et al., 1958; Ambrose &
Robbins, 1956b). Lipolytic studies in rats showed the presence of
large amounts of free fatty acids but only traces of free acetic acid
in the lipids isolated from the stomach after feeding acetoglycerides.
Ligation of the pylorus indicated a more rapid absorption of the
acetic acid moiety by the stomach wall than of glycerol and monoacetin
(Hertnig et al., 1956). Absorption of acetoolein or acetostearin,
given as 20% of the diet, was studied in groups of 10 adult male rats.
Acetooleins were better absorbed than acetostearins. Faecal lipid
estimations showed much greater absorption (i.e. lowest excretion) in
rats of unsaturated acetoglycerides (acetooleins) than of saturated
acetoglycerides (acetostearins) (Ambrose & Robbins, 1956b).
The digestibility coefficients of acetoglycerides fed as 20%
of the diet to rats varied between 94 and 99% depending on the
composition of the mixture administered (Ambrose & Robbins, 1956b).
In another study, groups of 10 male weanling rats were fed diets
containing 0 or 30% of two different acetostearins for 20 weeks.
Tissue cholesterol levels (plasma, liver, adrenal) for the 30% level
were similar to those in rats on a fat-free calorie-restricted diet
(Coleman et al., 1963).
TOXICOLOGICAL STUDIES
Acute toxicity
Animal Route LD50 mg/kg bw Reference
Rat oral 4 000 Ambrose & Robbins, 1956a
No toxic symptoms were seen in rats after single doses of
4000 mg/kg bw of acetostearin or acetoolein. Daily i.v. injection of
80-100 mg acetostearin into rabbits for 15 days caused no apparent ill
effects and viscera showed no pathological changes. Acetostearin
cleared completely from the blood plasma within 15 to 30 minutes
(Ambrose & Robbins, 1956a; Alfin-Slater et al., 1958).
Short-term studies
Rat
Groups of 10 male weanling rats received diets containing 25% of
either stearin, olein, diacetostearin or diacetoolein, and additional
groups received 50% olein or diacetoolein for eight weeks or 15%
acetoolein for 12 weeks. There was no difference between test and
control groups with regard to body weight gain, food consumption or
food efficiency, except for the groups receiving stearins. Only in the
groups receiving diacetostearin was the coefficient of utilization
markedly higher. Results of examination of blood and urine were normal
(Mattson et al., 1956). Studies for seven months on groups of five
male and 10 female rats using 10% acetostearin in the diet with
additional supplements of Vitamin E showed improved reproduction
performance (as measured by litter numbers and pups per litter in four
successive matings) compared with controls or animals on acetostearin
alone (Ambrose et al., 1958b).
Long-term studies
Rat
Six groups of five weanling male rats each were fed diets
containing 0, 0.25, 0.5, 1, 2 and 4% acetostearin and another four
groups of rats were fed diets containing 0, 0.25, 0.5 and 1.0%
acetoolein for 57 weeks. Body weight gain, food intake and mortality
did not differ from those of the controls. Measurement of relative
weights of major organs revealed decreased testicular weights at all
levels of acetoolein and with the 0.25% and 0.5% levels of
acetostearin. Microscopic examination showed no difference from
controls except for testicular hypoplasia and suppression of
spermatogenesis of a variable degrees in all test groups (Ambrose &
Robbins, 1956a).
In another experiment, three acetostearins and two acetooleins
were fed to groups of 10 male and 10 female rats each at 0, 5, 10 and
20% of their diet. Parental generation animals on 20% acetoglyceride
were sacrificed after 57 weeks, 86 weeks and 101 weeks. Mortality rate
was not increased at any dose level up to 57 weeks, but some increase
occurred in all test groups compared with controls after 86 weeks.
Body weight gain was slightly depressed at the 20% level. Examination
of major organs showed consistently reduced testicular weight at the
20% level of all three acetostearins and at the 5% and 10% levels of
two acetostearins. Significant liver enlargement was also observed at
the 20% level of acetostearins but liver glycogen was unaffected. Food
utilization was decreased by acetostearin more than by acetoolein
depending on dose. A variety of pathological changes were observed
with individual acetoglycerides at varying dietary levels, but these
changes were attributed to imbalance of the test diet with respect to
vitamin E and essential fatty acids. Fatty tissue changes reminiscent
of sclerema adiposum neonatorum (foci of foreign body reactions)
especially near the gut were seen with all acetostearins at 20% level
but none in the other groups (Ambrose et al., 1958a).
Comments:
Acetoglycerides are readily hydrolyzed in the gastrointestinal
tract and dealt with in the body in a manner similar to other
glycerides. The digestibility studies are only of limited value since
the inclusion of materials of this sort in an adequate quantity of
lipid fat, occurring naturally in the diet, ensures satisfactory
absorption. Dietary loads of a food additive in excess of 10% are of
little value in the assessment of safety-in-use as many irrelevant
effects may occur, such as observed with high dose levels of
acetostearins. (For example, testicular atrophy due to an increased
requirement for vitamin E, and foreign body reaction in adipose tissue
due to overloading with saturated fatty acids.) Evaluation is based on
the biochemical and metabolic studies because the breakdown products
are normal dietary constituents.
EVALUATION
Estimate of acceptable daily intake for man
Not limited.*1,2
*1 See relevant paragraph in the 17th Report, pp. 10-11.
*2 As sum of glycerol esters of fatty acids and acetic, citric,
lactic and tartaric acids, provided that the total food additive
intake of tartaric acid does not exceed 30 mg/kg.
REFERENCES
Alfin-Slater, R. B. et al. (1958) J. Amer. Oil Chem. Soc., 35, 122
Ambrose, A. M. & Robbins, D. J. (1956a) J. Amer. Pharm. Ass. Sci.
Ed., 45, 482
Ambrose, A. M. & Robbins, D. J. (1956b) J. Nutr., 58, 113
Ambrose, A. M., Robbins, D. J. & Cox, A. J., jr (1958a) Food Res., 23,
536
Ambrose, A. M., Robbins, D. J. & De Eds, F. (1958b) Food Res., 23, 550
Coleman, R. D., Gayle, L. A. & Alfin-Slater, R. B. (1963) J. Amer. Oil
Chem. Soc., 40, 737
Hertnig, D. C. et al. (1956) Fed. Proc., 15, 556
Mattson, F. H. et al. (1956) J. Nutr., 59, 277