INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY
WORLD HEALTH ORGANIZATION
TOXICOLOGICAL EVALUATION OF SOME
FOOD COLOURS, EMULSIFIERS, STABILIZERS,
ANTI-CAKING AGENTS AND CERTAIN
OTHER SUBSTANCES
FAO Nutrition Meetings Report Series
No. 46A WHO/FOOD ADD/70.36
The content of this document is the result of the deliberations of the
Joint FAO/WHO Expert Committee on Food Additives which met in Rome,
27 May - 4 June 19691
Food and Agriculture Organization of the United Nations
World Health Organization
1 Thirteenth report of the Joint FAO/WHO Expert Committee on Food
Additives, FAO Nutrition Meetings Report Series, in press;
Wld Hlth Org. techn. Rep. Ser., in press.
KARAYA GUM
Biological Data
Biochemical aspects
Karaya gum does not disintegrate appreciably in the alimentary tract.
In a study of 10 dogs 95 per cent. of the orally administered gum was
recovered in the faeces. It absorbs a large quantity of water and
therefore acts as a mechanical laxative. It tends to increase faecal
nitrogen excretion, does not affect starch digestion in the dog and
does not inhibit the utilization of vitamin A in rats (Ivy & Isaacs,
1938). The caloric value was determined in groups of 10 rats fed for
one week 5 g basal diet with either 1 g and 3 g corn starch or 1 g and
3 g Karaya gum supplements. At the 1 g level Karaya gum only had 30
per cent. of the caloric value of corn starch. At the 2 g level growth
was very depressed. The intestines were enlarged in all rats on gum
(Warf, 1964).
Acute toxicity
No data available.
Short-term studios
Rat. Examination of the intestines of rats fed 1 g of karaya gum per
day for 91 days showed no gross abnormalities. There was no
interference with normal growth (Ivy & Isaacs, 1938).
Dog. Three dogs were fed 5 g unprocessed karaya daily for 30 days.
Defaecations were more frequent, faecal bulk and moisture were
increased but there was no obvious gastro-intestinal irritation (Ivy &
Isaacs, 1938).
Man. Fifty subjects ate 4-6 g Karaya gum in ice-cream. No allergic
reactions were noted (Herzberg, 1963). Forty-six female and 43 male
subjects took karaya gum granules for one week at levels equivalent to
7 g per day. Seven subjects had abdominal discomfort (Ivy & Isaacs,
1938). Ingestion or inhalation was reported to have caused allergy
(Figley, 1950).
Sixteen cases of allergic sensitivity to inhalation of the gum used as
a wave set, and to oral ingestion as a laxative were reported.
Symptoms included hay fever, asthma, dermatitis and gastro-intestinal
distress (Figley, 1940).
In a comparison with carob bean gum as a laxative in 10 human subjects
karaya gum was found to be transformed to a gelatinous state at a
higher level in the intestine and to be transported more rapidly
through the intestinal tract (Holbrook, 1951).
Long-term studies
Rat. Five rats were fed 20 per cent. karaya gum in the diet for two
years. Three developed enlarged colon and ulceration (Hoelzel et al.,
1941). In another experiment groups of three rats were fed karaya gum
at first at 10 per cent., gradually increasing to 25 per cent. in the
diet over their life span. Controls of five and seven animals received
low residue diets. No caecal ulceration was found in this experiment
(Carlson & Hoelzel, 1948).
Comments
Karaya gum has a long history of human use as a laxative agent. There
is evidence in a few species that the gum might irritate the bowel. In
a few cases allergic responses in man have been recorded. The
long-term tests reveal only enlargement of the colon but are
inadequate. Metabolic studies in several species, preferably including
man, and adequate 90-day studies in several species are required.
Special attention might be paid to determining the frequency of
allergic reactions when a product is used that conforms to these
specifications.
EVALUATION
Not possible on the data available.
REFERENCES
Carlson, A. J. & Hoelzel, F. (1948) J. Nutr., 36, 27
Figley, K. D. (1950) J. Amer. med. Ass., 114, 747
Hoelzel, F., Costel, E. & Carlson, A. J. (1941) Amer. J. dig. Dis.,
8, 266
Holbrook, A. A. (1951) Amer. J. dig. Dis., 18, 24
Ivy, A. C. & Isaaas, B. L. (1938) Amer. J. dig. Dis., 5, 315
Wisconsin Alumni Research Foundation Lab. (1964) Unpublished report
No. 3110860/1 to Stein, Hall and Co.