INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY
WORLD HEALTH ORGANIZATION
TOXICOLOGICAL EVALUATION OF SOME
FOOD COLOURS, ENZYMES, FLAVOUR
ENHANCERS, THICKENING AGENTS, AND
CERTAIN FOOD ADDITIVES
WHO FOOD ADDITIVES SERIES 6
The evaluations contained in this publication were prepared by the
Joint FAO/WHO Expert Committee on Food Additives which met in Rome,
4-13 June 19741
World Health Organization Geneva 1975
1 Eighteenth Report of the Joint FAO/WHO Expert Committee on
Food Additives, Wld Hlth Org. techn. Rep. Ser., 1974, No. 557.
FAO Nutrition Meetings Report Series, 1974, No. 54.
BETA-CAROTENE
Explanation
This compound has been evaluated for acceptable daily intake by
the Joint FAO/WHO Expert Committee on Food Additives (see Annex 1,
Ref. No. 10) in 1966.
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
In man 30-90% of ingested beta-carotene is excreted in the faeces
and concomitant intake of fat does not improve absorption. Excessive
doses depress the Vitamin A activity of the absorbed fraction. Only
small amounts appear in the serum. Beta-carotene dissolved in oil is
much better absorbed, 10-41% for adults, 50-80% for children (Fraps &
Meinke, 1945).
Vitamin E is necessary to prevent enzymatic destruction and bile
acids are necessary for absorption (Wagner, 1962).
Other workers quote 11% absorption by adults and 2.6% by babies
of a dose of 20 mg carotene (Kübler, 1963).
The major fraction of absorbed beta-carotene passes unchanged
through the gut wall and reaches the liver via the portal system and
to a small extent via the lymphatics. Some beta-carotene is stored in
the liver but is never released as such, and some is converted to
Vitamin A in jejunum, liver, lung, muscle and serum and stored in the
liver as Vitamin A. Large doses lead to a rise in serum carotene and
subsequent deposition in organs and the horny layer of the skin
without necessarily raising the Vitamin A serum level (Zbinden &
Studer, 1958).
Gastrointestinal and liver and renal disease, diabetes mellitus
and phosphor poisoning reduce the conversion to Vitamin A and
myxoedema blocks conversion. Infants and small children have a smaller
capacity for this conversion (Wagner, 1962).
Beta-carotene is transmitted in milk. In infants a single
administration of 20 mg of beta-carotene in milk produces a rise in
the beta-carotene blood level, peaking in 24 hours and a rise in the
Vitamin A ester blood level but practically no change in the Vitamin A
alcohol blood level (Auckland, 1952).
TOXICOLOGICAL STUDIES
Special studies
Special studies on hypercarotenemia
Hypercarotenemia per se is harmless and causes no symptoms nor
is there normally any evidence of hypervitaminosis A. It disappears if
excess intake of beta-carotene is discontinued (Abrahamson et al.,
1962; Nieman et al., 1954). No hypervitaminosis A was noted in
volunteers given beta-carotene over extended periods (Bagdon et al.,
1960).
The possibility of producing hypervitaminosis A in animals by
hypercarotenemia has never been completely proven because of the poor
absorption and slow conversion. No effects have been shown in rats
given the equivalent of 40 000-70 000 IU Vitamin A esters/day either
i.v., i.p. or orally. However, oral or s.c. doses equivalent to
1500 IU Vitamin A/day caused accelerated epithelial growth in adult
rats and changes in oestrus (Nieman et al., 1954). In another
experiment, 20 mg/kg bw of beta-carotene was fed to 30 young rats on a
Vitamin A-deficient diet for 6 to 11 months without any deleterious
effects, particularly without evidence of hypervitaminosis A or liver
damage.
High doses of beta-carotene reduce liver storage of labelled
dl-gamma-tocopherol acetate to 70% (Brubacher et al., 1965).
Acute toxicity
LD50
Animal Route mg/kg bw Reference
Rat i.m. (oil) > 1 000 Zbinden & Studer, (1958)
Dog Oral > 8 000 Nieman et al., (1954)
Short-term studies
Several short-term studies in rat and dog showed the same results
as the human studies reported (Anonymous, 1960).
Long-term studies
Rat
A four-generation study at dietary levels of 0 ppm and 1000 ppm
of beta-carotene for 110 weeks showed no adverse effects in any of the
generations (Bagdon et al., 1960).
OBSERVATIONS IN MAN
Fifteen subjects received 60 mg beta-carotene daily for three
months. Serum carotene levels rose from 128 µg to a maximum of
308 µg/100 ml after one month while Vitamin A levels remained
unchanged. No clinical signs of hypervitaminosis A were seen.
(Greenberg et al., 1959). Other subjects ate several pounds of raw
carrots daily, resulting in some skin discoloration. Beta-carotene
appeared in the milk (Zbinden & Studer, 1958).
Comments:
Beta-carotene is a normal constituent of the human diet and is
commonly ingested over the entire lifespan of man. Its biological
importance rests on the provitamin A function. Concerning the known
clinical syndrome of hypervitaminosis A in man, evidence from human
experience indicates that in very exceptional circumstances excessive
dietary intakes can occur. Such cases have been reported in the
literature but do not relate to food additive use of this colour.
Despite poor absorption from the gastrointestinal tract cases of human
hypervitaminosis have occurred. The results of short-term toxicity
studies in rats and dogs have shown that over a wide range of doses
toxic effects have not been produced. Similarly, multigeneration tests
in rats using levels up to 1000 ppm have not revealed any adverse
effects.
In the light of the above comments it appears justifiable to
apply a smaller safety factor to the no-effect level established in
long-term studies.
EVALUATION
Level causing no toxicological effect
Rat: 0.1% (= 1000 ppm) in the diet equivalent to 50 mg/kg bw.
Estimate of acceptable daily intake for man
0-5 mg/kg bw*
REFERENCES
Abrahamson, I. A. sr & Abrahamson, I. A. jr (1962) Arch. Ophth., 68, 4
Auckland, G. (1952) Brit. Med. J., 2, 267
Bagdon, R. E., Zbinden, G. & Studer, A. (1960) Toxic. Appl. Pharm., 2,
223
Bernhard, K. (1963) Wiss. Veröff. Dtsch. Gesellsch. Ernährung, 9, 169
Brubacher, G. et al. (1965) Z. Ernährw., 5, 190
Fraps, G. S. & Meinke, W. W. (1945) Arch. Biochem., 6, 323
Greenberg, R., Cornbleet, T. & Joffay, A. I. (1959) J. Invest.
Dermatol., 32, 599
Hoffmann-La Roche (1960) Unpublished report submitted to WHO
Kübler, W. (1963) Wiss. Veröff. Dtsch. Gesellsch. Ernährung., 9, 222
Nieman, C. & Klein, Obbink, H. J. (1954) Vit. Horm., 12, 60
Wagner, K. (1962) Wien, Kl. Wschr., 74, 909
Zbinden, J. & Studer, A. (1958) Z. Lebensm. Unters. Forsch., 108, 114
* As sum of the carotenoids; Beta-carotene
Beta-apo-8'-carotenal
Beta-carotenoic acid methyl ester
Beta-carotenoic acid ethyl ester
See Also:
Toxicological Abbreviations