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.
PECTIN
Explanation
This substance has been evaluated for acceptable daily intake by
the Joint FAO/WHO Expert Committee on Food Additives (see Annex 1,
Ref. No. 19) 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
These partially methoxylated polygalacturonic acids occur
naturally and widely in fruits especially citrus fruits and apples and
are part of the cell walls. They are therefore part of the normal
diet. For the past 30 years some newer pectins have been in use, in
which the de-esterified carboxyl groups have been partially amidated.
At one time pectins have been used as plasma extenders as 1%
solution but large intravenous doses have led to pectin deposition in
the kidney, liver and lungs with consequential degenerative changes
(Merck Index, 1968). Pectin has been shown to lower blood cholesterol
in man (Keys et al., 1961) and in the rat (Wells & Ershoff, 1961).
Four groups of three male and three female pigs were given diets for
four weeks supplemented with either 5% pectin or 5% cellulose with or
without dietary cholesterol. Pectin had no effect on body weight or
plasma cholesterol level unless cholesterol was given in the diet.
Pectin lowered significantly alimentary hypercholesterolaemia (Fischer
et al., 1966; Fisher & Kannitz, 1964). Chicken fed cholesterol in the
diet excrete more cholesterol if pectin is also added. Pectin has no
effect on endogenous plasma cholesterol or may raise the level
(Fisher et al., 1964). On the otherhand swine fed pectin developed
significantly higher blood cholesterol levels in other experiments
(Fausch & Anderson, 1965).
The digestibility of pectin was determined in groups of six rats
fed 17.4% or 34.8% pectin in their diet for three weeks. At the lower
dietary level there was no adverse effect on the utilization of other
nutrients but at the higher level utilization of other nutrients was
reduced. Pectin produced diarrhoea and growth was retarded at both
dietary levels. Faecal recovery showed only 20% of orally ingested
pectin to be digestible (Carey, 1958).
Rats were fed diets containing 0.04 ppm (0.000004%) Pb210 and
either 5% pectin or 5% starch. The control group retained 15.8% of the
radioactive lead and excreted 10.9% in the urine and 71.7% in the
faeces. The pectin fed animals retained an average of 24% less lead
than controls, significantly less being excreted in the urine and more
in the faeces (Murer & Crandall, 1942).
Four normal dogs and two dogs with ileotomies were fed 140 g of
pectin in a mixed diet over a seven-day period. An average of 90% of
the pectin was broken down. When fed during fasting periods an average
of only 50% was broken down. In the case of studies with humans, more
pectin was broken down than in the dog study. A study involving two
human patients with ileotomies, showed that the breakdown of pectin
occurred in the colon rather than in the upper intestine, and that
bacterial enzymes were involved rather than enzymes of the animal
organism (Werch & Ivy, 1941).
TOXICOLOGICAL STUDIES
Acute toxicity
None available.
Short-term studies
Rat
Rats were fed 2.5-10% pectin without any deleterious effects - no
details are available (Ershoff & McWilliams, 1945).
In another experiment four groups of 10 male and 10 female rats
were fed diets containing 0, 5%, 10% or 15% pectin (non-amidated) for
90 days. No adverse effects were noted on general condition, behaviour
and survival. Growth was slightly decreased at the 15% level, an
observation previously noted in a range-finding test using 20% pectin.
At 20% also reduced food consumption and food efficiency had been
noted. Total serum protein and albumin were decreased at the 15% level
but the haematological indices showed no treatment related
differences. Blood chemistry showed no significant findings. The
relative caecal weight was increased at the 15% level, a phenomenon
also seen with modified starches and other high food intake of complex
carbohydrates. Gross and histopathology were essentially normal
(Til et al., 1972).
In another experiment four groups of 10 male and 10 female rats
were fed on diets containing 0%, 5%, 10% or 15% pectin (21% amidated)
for 90 days. No adverse effects were noted on general condition,
behaviour and survival. Growth was slightly decreased at the 15% level
and this finding was also noted in a range finding test using 20%
pectin, in the diet. Some decrease in growth occurred inconsistently
also at the 10% dietary level. Food intake and food efficiency were
not affected at any level. Haematological parameters showed no
significant treatment related changes. Total serum protein and albumin
were reduced at the 15% level but the other clinical biochemical
parameters and urinalysis were essentially normal. Caecal weights
were increased at all levels but in a dose-related manner. These
findings are reminiscent of what is seen when high amounts of starch,
modified starch or certain other carbohydrates are fed. Gross and
histopathology were normal but a slight degree of hyperkeratosis of
the fore-stomach in some males was seen at the 10% and 15% level but
is probably not of toxicological significance (Til et al., 1972).
Long-term studies
None available.
Comments:
Non-amidated pectins and their salts as specified are normal
constituents of the human diet and have also been administered
intravenously at high levels to man without acute toxic effects. The
available short-term tests show that even at 15% dietary levels no
adverse effects are seen. The caecal enlargement without any
accompanying histological changes is considered to be related to the
presence of large amounts of a polysaccharide in the diet. Little
formal testing has been carried out and does not appear necessary for
the natural non-amidated product. On the other hand amidated pectins
appear to be somewhat more toxic and only the 5% level produces no
adverse effects apart from the expected caecal enlargement.
EVALUATION
1. Non-amidated pectin
Not limited.*
2. Amidated pectin
Level causing no significant toxicological effect
Rat: 50 000 ppm (5%) in the diet equivalent to 2500 mg/kg bw.
Estimate of acceptable daily intake for man
0-25 mg/kg.**
* See relevant paragraph in the seventeenth report, pp. 10-11.
** Temporary.
FURTHER WORK OR INFORMATION
Required by 1974. Provision of full specification.
REFERENCES
Carey, P. L. (1958) Thesis submitted to Purdue University
Ershoff, B. H. & McWilliams, H. B. (1945) Amer. J. dig. Dis., 12, 21
Fausch, H. D. & Anderson, T. A. (1965) J. Nutr., 85, 145
Fisher, H. et al. (1966) J. Atheroscler. Res., 6, 190
Fisher, H., Griminger, P. & Weiss, H. S. (1964) Science, 145, 1063
Fisher, H. & Kannitz, H. (1964) Proc. Soc. Exp/l Biol. Med., 116, 278
Keys, A., Grande, F. & Anderson, J. T. (1961) Proc. Soc. Exp/l Biol.
Med. (N.Y.) 106, 555
Merck Index (1968)
Murer, H. K. & Crandall, L. A. jr (1942) J. Nutr., 23, 249
Til, H. P., Seinen, W. & de Groot, A. P. (1972) CIVO Report No. 3843
dated August 1972
Wells, A. F. & Ershoff, B. J. (1961) J. Nutr., 86, 113
Werch, S. C. & Ivy, A. C. (1941) J. Digest. Dis., 8, 101