IPCS INCHEM Home

WHO FOOD ADDITIVES SERIES: 48

SAFETY EVALUATION OF CERTAIN
FOOD ADDITIVES AND CONTAMINANTS

QUILLAIA EXTRACTS

First draft prepared by Jennifer Eastwood1, Elizabeth Vavasour1 and Janis Baines2
1
Bureau of Chemical Safety, Food Directorate, Health Products and Food Branch, Health Canada, Ottawa, Ontario, Canada
2Australian New Zealand Food Authority, Canberra, Australia

Explanation

Biological data

Biochemical aspects: Effects on enzymes and other biochemical parameters

Toxicological studies

Acute toxicity

Short-term studies of toxicity

Long-term studies of toxicity

Intake

Screening for additives by the budget method

Poundage data

Individual dietary records

Evaluation of intake estimates

Comments

Evaluation

References

1. EXPLANATION

Quillaia extracts (synonyms, soapbark extracts, Quillay bark extracts, bois de Panama, Panama bark extracts, quillai extracts) are obtained by aqueous extraction of the milled inner bark or of the wood of pruned stems and branches of Quillaja saponaria Molina (family Rosaceae). The term ‘quillaia’ refers to the dried inner bark of the tree, which is a large evergreen with shiny, leathery leaves and a thick bark, native to China and several South American countries, principally Bolivia, Chile, and Peru.

Unpurified extracts contain over 60 triterpenoid saponins, consisting predomi-nantly of glycosides of quillaic acid. Polyphenols and tannins are major components. Some simple sugars and calcium oxalate are also present. The saponin concentration of freshly prepared, unpurified extracts is 190–200 g/kg of solids (about 20%). The extracts are treated with ‘stabilizing agents’ such as egg albumin and polyvinyl-pyrrolidone and then filtered through diatomaceous earth. The stabilizing agents remove substances that would probably precipitate during storage, such as protein–polyphenol complexes. After filtration, the liquid is concentrated, and the concentrate may be sold as such (solids constituting about 550 g/L) or be spray-dried and sold as a powder containing carriers such as lactose and maltodextrin. The unpurified extracts are used in food applications, primarily for their foaming properties.

Semi-purified powdered extracts are produced by subjecting unpurified extracts to ultra-filtration or affinity chromatography to remove most non-saponin solids, such as polyphenols. These semi-purified extracts have higher saponin concentrations (750–800 g/kg of solids; about 80%) and better emulsifying properties than unpurified extracts.

Highly purified extracts are produced for use as adjuvants in the production of animal and human vaccines and not for food use. These products generally contain more than 90% saponins.

In previous evaluations, the Committee considered data that related to unpurified quillaia extracts. Quillaia extract was reviewed toxicologically by the Committee at its twenty-sixth meeting (Annex 1, reference 59). The available toxicological data included adequate lifetime studies in mice and rats, from which a NOEL was identified. However, in the absence of data, no specifications were prepared, and, hence, no ADI could be allocated. At its twenty-ninth meeting (Annex 1, reference 70), the Committee prepared new tentative specifications and established an ADI of 0–5 mg/kg bw. The Codex Committee on Food Additives and Contaminants (CCFAC) (2000) at its thirty-second session requested the Expert Committee to re-evaluate all relevant information on the toxicity and, in particular, the intake of quillaia extracts. No new data were submitted to the Committee. Published reports on quillaia extracts or specific saponins that provided information relevant to a toxicological assessment of quillaia extracts were evaluated at the present meeting.

Quillaia extracts are mixtures of biologically active compounds, including saponins, tannins, polyphenols, and calcium oxalate. The saponins present in quillaia extract have a variety of biological activities: haemolytic, cytotoxic, immune-enhancing (adjuvant), mucosal irritation and inflammation, and anti-hypercholesterolaemic. The biological activities and the potency of individual saponins vary widely and depend in vivo primarily on the route of administration.

2. BIOLOGICAL DATA

2.1 Biochemical aspects: Effects on enzymes and other biochemical parameters

Saponins extracted with ethanol from soapbark trees and administered orally to rabbits with experimental atherosclerosis resulted in an increased ratio of plasma lecithin to cholesterol, normalized blood cholesterol levels, and decreased elevated blood pressure. Subcutaneous injection of the saponin extract did not affect the atherosclerotic symptoms (Efimova et al., 1966).

Groups of 12 Swiss mice (strain and sex unstated) were injected into the footpad with aliquots of seven different 5% extracts of Q. saponica bark. Animals that lived longer than 24 h and controls were killed. The degree of oedema in the mice, haemolysis of rabbit erythrocytes, and the adjuvant strength of the various extracts in stimulating immunity to staphylococcal toxin were measured with the same quillaia extracts. No relationship was found between these parameters (Richou et al., 1965).

The effect of a range of saponins, including crude quillaia saponin on gut permeability was assessed by monitoring the steady-state glucose transfer potential in vitro in sections of jejunal mucosa from male Wistar rats. The individual saponins elicited widely different responses in the small gut and these were significantly affected by pH, concentration, chemical formula, and the presence of other materials in the solution. Quillaia extract caused a reduction in transmural potential difference comparable to that observed with the basic glycoalkaloids in potato and tomato and the complex bisdesmosides from Gypsophilia and alfalfa. These saponins were all more potent than the saponins from soya, which showed only weak activity. The reduction in transmural potential difference has been associated with increased uptake of both passively permeable sugars and large compounds and with a loss of the ability of the mucosa to accumulate actively transported organic species(Gee et al., 1989).

When ‘pure’ saponin from Q. saponaria was administered subcutaneously to mice that had been immunized with bovine serum albumin or Crotalus durissus (South American rattlesnake) venom, a significantly higher antibody titre against the antigens was found in the sera of immunized mice than in animals receiving the antigens alone. Tumour necrosis factor activity was increased in mice immunized with bovine serum albumin and/or saponin, but interferon-gamma was produced only in mice immunized with both bovine serum albumin and saponin (Gebara et al., 1995).

The effect of the Quillaia saponin fractions QH-A, QH-B, and QH-C and a crude Quillaia saponin extract (Spikoside) on haemolytic activity, cytotoxicity, and macromolecular synthesis was studied in vitro. A concentration of 5 µg/ml of QH-B or QH-C caused haemolysis of chicken erythrocytes after 1 h of incubation at 37 oC. QH-A was haemolytic at an approximately 10-fold higher concentration, 50 µg/ml. The crude extract caused haemolysis at a concentration of 20 µg/ml. No haemolytic activity was observed at concentrations <100 µg/ml when these preparations were incorporated into an immunostimulating complex matrix. Cytotoxicity was assessed by measuring intracellular dehydrogenase activity by a colorimetric method. Seeded WEHI 164 cells clone 139 were incubated with various concentrations of the extracts for 2 h before analysis. QH-B and QH-C inhibited enzyme activity at a concentration of approximately 10 µg/ml and the crude extract at a concentration of approximately 20 µg/ml. QH-A was tolerated at concentrations <100 µg/ml. When QH-A, QH-B, QH-C, and the crude extract were incorporated into the immunostimulating complex matrix, the cells tolerated approximately 10-fold higher concentrations. Macromolecular synthesis was assessed by measuring incorporation of [3H]leucine and [3H]uridine into protein and RNA, respectively, in WEHI 164 cultured cells. Treatment with QH-B or QH-C at concentrations <10 µg/ml for 30 min had no affect on protein or RNA synthesis (Rönnberg et al., 1995).

2.2 Toxicological studies

Saponins vary widely in the kind and intensity of their biological activity. Some of the more important effects included haemolysis (strong in vitro, much weaker in vivo), local irritation, inflammation (intestine), anti-inflammatory and antimicrobial activity, cytotoxicity, and anti-hypercholesterolaemic in laboratory animals. Severe toxic effects reported after large oral doses were liver damage, respiratory failure, gastric pain, diarrhoea, haemolysis of erythrocytes, convulsions, and coma (Leung, 1980).

2.2.1 Acute toxicity

In mice, saponins extracted from the soapbark tree were less acutely toxic when administered orally (LD50, 1600 mg/kg bw) than when administered subcutaneously (650 mg/kg bw), intraperitoneally (280 mg/kg bw), or intravenously (280 mg/kg bw) (Efimova et al., 1966).

The acute toxicity of a Q. saponaria extract and of QS-7, QS-18, and QS-21 saponins isolated from the extract was investigated in groups of five CD-1 mice (sex not stated), 8–10 weeks of age given an intradermal concentration of 125, 250, or 500 µg of each saponin or the quillaia extract and monitored for 72 h. QS-18 was the most lethal of the substances tested, with 4/5, 5/5, and 5/5 deaths at the three doses, respectively. The authors stated that deaths occurred at a dose of QS-18 as low as 25 µg. QS-7 was not lethal at doses up to 500 µg, and QS-21 was lethal only at 500 µg, at which 1/5 mice died. The quillaia extract resulted in the deaths of 1/5, 2/5, and 4/5 mice at the three doses, respectively (Kensil et al., 1991).

The acute toxicity of subcutaneously administered QH-A, QH-B, QH-C, and crude Quillaia saponin (Spikoside) was tested in groups of 10 female ICR mice at doses of 50–400 µg. All mice survived after the highest dose of QH-A and QH-C, with no visible signs of toxicity. All mice given 400 µg QH-B died within 12 h, while seven mice survived injection with 200 µg. When the crude extract was administered, doses of 200 and 400 µg resulted in 6 and 10 deaths, respectively. All mice survived the lower doses of QH-B or the crude extract (Rönnberg et al., 1995).

A purified, toxic Quillaia triterpenoid fraction with strong adjuvant activity, designated QH-B, was used to study whether modification of the carbohydrate moiety with sodium periodate would alter the toxicity without harming the adjuvant activity and the cholesterol-binding capacity. Groups of 10 ICR female mice received single increasing subcutaneous doses of modified QH-B and were observed for 3 weeks. Unmodified QH-B and QH-B modified by treatment with 2.5–10 mmol/L sodium periodate had similar LD50 values, ranging from 29 to 70 µg per mouse. Treatment of the fraction with 25 or 50 mmol/L sodium periodate increased the LD50 of QH-B to 197 and 132 µg, respectively. The difference in the toxicity of the periodate-modified QH-B may have been due to alterations in the structure of the sugars galactose and xylose (Rönnberg et al., 1997).

2.2.2 Short-term studies of toxicity

Rats

Groups of 15 male and 15 female weanling CFE rats were housed five per cage and fed diets containing 0 (control), 0.6, 2, or 4% quillaia extract for 13 weeks. Groups of five male and five female rats from the same lot of animals were fed diets containing 0 (control), 2.0%, or 4.0% quillaia extracts for 2 or 6 weeks. Body weights and food intake were measured at the beginning and weekly throughout the study. Urine was analysed during the final week of the study. At sacrifice, the absolute and relative organ weights were determined, and tissues and organs from the group given 4% were analysed histologically. Haematological and serum chemical parameters were tested in all groups.

No abnormalities of behaviour or condition were seen in the rats receiving quillaia extract. The body weights of those at the highest concentration (4%) were significantly lower than those of controls up to day 78 in males, but only for the first 2 weeks in females. Food and water consumption were reduced in animals of each sex at all dietary levels, but by the end of the study the weights of the treated rats did not differ significantly from those of the controls. Feeding quillaia saponin did not affect the results of haematological examinations, serum or urine analyses, renal concentrating ability, or urinary cell excretion. The relative liver weight was reduced in males given 2 or 4% quillaia extract, and the relative stomach weight was increased in animals of each sex at the same concentrations. No histopathological effects attributable to treatment were found. The NOEL was 0.6% in the diet, equivalent to 400 mg/kg bw per day (Gaunt et al., 1974).

In a 90-day study to assess the safety of a saponin extract from Thea sinensis L., quillaia saponin (approximately 8.5% sapogenin; not clear whether this product meets current specifications) was used for comparison. Although the Committee examined this study, it was considered irrelevant to the toxicological assessment of quillaia extracts as sufficient data were not available on the specifications of the test material and because the animals were given the compound by gavage (Kawaguchi et al., 1994).

2.2.3 Long-term studies of toxicity

Mice

Groups of 48 male and 48 female TO strain mice were fed diets containing 0, 0.1, 0.5, or 1.5% quillaia extract for 84 weeks. The mice were observed regularly for abnormal condition or behaviour, and some males were weighed at intervals. Haematological parameters were measured at weeks 24, 56, and 84. No compound-related effects were reported. At the highest dose, male mice showed decreased weight gain. Quillaia at these concentrations had no adverse effect on condition, behaviour, or death rate. A detailed autopsy and histopathological examination of tissues and organs at the end of the study showed no compound-related effects. No carcinogenic effects were seen. The slightly lower body-weight gain of mice at the highest dietary concentration and some changes in organ weights, albeit of doubtful significance, resulted in a NOEL of 0.5%, equivalent to 700 mg/kg bw per day (Phillips et al., 1979).

Rats

Groups of 48 male and 48 female Wistar-derived rats from a specific pathogen-free breeding colony were housed in groups of four and fed diets containing 0 (control), 0.3, 1, or 3% quillaia extract for 108 weeks. Haematological examinations were made at weeks 15, 25, 52, and 108, and urine was analysed at weeks 13, 24, and 78. At the end of the study, a complete autopsy was carried out, including histological examination of tissues and organs.

Male rats at the highest dietary concentration had lower body weights than controls throughout the experiment, the differences being statistically significant between 10 and 22 months. Females at the lowest dietary concentration had significantly higher body weights than controls during the first 6 months of the study. The lower body weights and reduced incidence of glomerulonephrosis in male rats fed 3% quillaia were considered to be due to reduced food consumption. Preference tests run before the start of the 2-year study showed that rats avoided the diet containing quillaia extract. Haematological and urinary parameters were within the normal ranges.

In general, the incidence of histopathological lesions was similar in treated and control animals, only those of fibrosis of the heart and dilatation of the glands of the gastric mucosa in females at the lowest dietary concentration being greater than those of controls. These effects were considered to be fortuitous, as there was no dose–response relationship and no similar occurrence in males. A variety of benign and malignant tumours was found. The incidences of haemangiomas and haemangio-sarcomas in the lymph nodes were similar in control and treated animals. The only tumour for which the incidence was statistically significantly different from that in controls was thyroid adenoma, which occurred more frequently in females fed 1% quillaia in the diet. This finding was not considered to be related to treatment, as the incidence did not increase with the dietary concentration of quillaia extract, and the total incidence in rats fed 1% quillaia extract was not statistically significantly different from the total control incidence (Drake et al., 1982).

3. INTAKE

Quillaia extracts may be used as a foaming agent in soft drinks, such as ginger beer, root beer, and cream soda, in cocktail mixes, and as an emulsifier in other foods, such as baked goods, candies, frozen dairy products, gelatine, and puddings. The major food use is in soft drinks. Quillaia extracts are currently proposed for use in the Codex draft General Standard for Food additives (GSFA) at 500 mg/kg in food group 14.1.4 ‘Water-based flavoured drinks’, including ‘sport’ or ‘electrolyte’ drinks and particulated drinks.

Data on intake of quillaia extracts were submitted to the Committee by Australia and New Zealand, the United Kingdom, and the USA.

3.1 Screening for additives by the budget method

The budget method was used to decide whether the intake of quillaia extracts should be assessed further. The calculations indicated that the theoretical maximum level of use of quillaia extracts is 100 mg/kg, assuming that it is used in only half the beverages in a food supply and that the ADI is 0–5 mg/kg bw. As this theoretical level is lower than the proposed level of 500 mg/kg in the draft GSFA, further assessment of intake is needed. The draft GSFA proposes use of quillaia extract in one food group only, 14.1.4 ‘Water-based flavoured drinks’.

As quillaia extracts are proposed for use in a single food group, a reverse budget method was used to indicate the maximum amount of the food group that can be consumed before the ADI is exceeded. In this case, up to 600 g/day of water-based flavoured drinks could be consumed if quillaia extracts were used at a concentration of 500 mg/kg, assuming an ADI of 0–5 mg/kg bw and an average body weight of 60 kg, while a child of 15 kg can drink only 150 g/day before exceeding the ADI.

If quillaia extracts were used at 100 mg/kg (the maximum manufacturers’ use levels are 95 mg/kg in the United Kingdom and 100 mg/kg in the USA), up to 3000 g/day of water-based flavoured drinks could be consumed before the ADI was exceeded, assuming an ADI of 0–5 mg/kg bw, an average body weight of 60 kg, and up to 750 g/day for a 15-kg child.

3.2 Poundage data

Poundage (disappearance) data were available from the USA, based on information reported to the National Academy of Sciences (1989): 38 600 pounds (17 500 kg) of quillaia extracts were reported to have been used in food applications in 1987. The intake of quillaia extracts per capita was calculated to be 0.0055 mg/kg bw per day (0.1% ADI), assuming a body weight of 60 kg and 60% response to the survey (raw poundage data divided by 0.6 to account for underreporting). The per capita intake at the 90th percentile was calculated by multiplying by a factor of 2, to give 0.011 mg/kg bw per day or 0.2% ADI (use of factor discussed in WHO, 1987).

3.3 Individual dietary records

Estimates of the intake of quillaia extracts based on individual dietary records from national surveys in Australia and New Zealand, the United Kingdom, and the USA were based on consumption of the whole water-based flavoured drinks category or those soft drinks likely to contain the additive. The estimates and the assumptions made in deriving the estimates are summarized in Table 1.

Table 1. Estimated intakes of quillaia extracts from individual dietary records

Country and reference

Population group

Soft drink consumption (g/day)

Quillaia extract intake(mg/kg bw per day)

% ADIa

Assumptions

Survey

Date of survey

Australia
(Australia–New Zealand Food Authority, 2001a)

All respondents
Consumers only
Consumers only




All respondents
Consumers only
Consumers only

Mean, 240
Mean, 590
Median, 410
95th percentile, 1600



Mean, 9
Mean, 380
Median, 310
95th percentile, 800

Mean, 2.3
Mean, 5.5
Median, 3.7
95th percentile, 16



Mean, 0.07
Mean, 3.0
Median, 2.2
95th percentile, 7.2

47
110
74
320



1.4
59
45
140

Extract in all water-based drinks; GSFA level, 500 mg/kg; consumers, 41% of population

Extract in limited number of soft drinks only; GSFA level, 500 mg/kgb; consumers, 2% of population

National survey, single 24-h recall, 13 858 sample; > 2 years; mean body weight, 67 kg; individual body weights used in calculations

1995

New Zealand
(Australia–New Zealand Food Authority, 2001b)

All respondents
Consumers only
Consumers only

Mean, 180
Mean, 510
Median, 370
95th percentile, 1600

Mean, 1.1
Mean, 3.4
Median, 2.5
95th percentile, 9.8

23
69
49
200

Extract in all water-based drinks; GSFA level, 500 mg/kg; consumers 35% of population

National survey, 4636 sample; single 24-h recall; > 15 years; mean body weight, 71 kg, individual body weights used

1997

United Kingdom
(Food Standards Agency, 2001)

Adult respondents
Adult consumers




Adult respondents
Adult consumers




Child respondents
Child consumers




Child respondents
Child consumers

Mean, 120
97th percentile, 640




Mean, 120
97th percentile, 640




Mean, 260
97th percentile, 800




Mean, 260
97th percentile, 800

Mean, 1.0
97th percentile, 5.3




Mean, 0.2
97th percentile, 0.1




Mean, 8.8
97th percentile, 28




Mean, 1.7
97th percentile, 5.2

19
110




4
20




180
550




34
100

GSFA, 500 mg/kg; extract in all water-based drinksc; consumers 22%

Maximum manufacturers’ use level, 95 mg/kg; extract in all water-based drinks

GSFA, 500 mg/kg; extract in all water-based drinksc; consumers 87%

Maximum manufacturers’ use level, 95 mg/kg; extract in all water-based drinks

National survey; 7-day records; adults 16–64 years; sample, 2197; assumed body weight, 60 kg





National survey; 7-day records; children 1.5–4.5 years; sample, 1675; assumed body weight, 14.5 kg

1986–87











1992

USA (Food & Drug Administration, 2001)

Consumers only
Consumers only





All respondents
Consumers only
Consumers only

Mean, 180
90th percentile, 330





Mean, 7
Mean, 180
90th percentile, 330

Mean, 1.5
90th percentile, 2.7





Mean, 0.01
Mean, 0.3
90th percentile, 0.5

30
54





0.2
6
11

Extract in brewed soft drinks only; GSFA level, 500 mg/kg; consumers 3.8% of population

Extract in limited number of soft drinks only, maximum level of use, 100 mg/kgb; consumers 3.8% of population

National survey; 3-day intake (one 24-h record plus self-reported daily intake, weighted data); sample, 11 912; assumed body weight, 60 kg

1989–92
(combined surveys)

a JECFA ADI, 0–5 mg/kg bw

b Soft drinks likely to contain the additive are, e.g. ginger beer, root beer and cream soda.

c Calculated from data given in submission from the United Kingdom

If use of quillaia extracts is assumed to be at the GSFA level (500 mg/kg) in all water-based drinks, the intake would exceed the ADI for consumers in Australia at the mean level (5.5 mg/kg bw per day or 109% of the ADI) and at the high level (16 mg/kg bw per day or 316% of the ADI) and for consumers at the high level in New Zealand (9.8 mg/kg bw per day or 196% of the ADI), for child respondents in the study in the United Kingdom (8.8 mg/kg bw per day or 177% of the ADI), and for consumers at the high level among both child (28 mg/kg bw per day or 550% of the ADI) and adult consumers (5.3 mg/kg bw per day or 106% of the ADI) in the United Kingdom.

Estimates of intake based only on soft drinks likely to contain quillaia extracts and the level of use stated in the draft GSFA were submitted by Australia and the USA. The mean intake of quillaia extracts by consumers in Australia was below the ADI (3 mg/kg bw per day, 59% of the ADI), but that of consumers of large amounts of soft drinks likely to contain the additive exceeded the ADI (7.2 mg/kg bw per day, 145% of the ADI). The estimated intakes of quillaia extracts in the USA were 1.5 mg/kg bw per day (30% of the ADI) for consumers at the mean level and 2.7 mg/kg bw per day (54% of the ADI) for those at the 90th percentile of consumption.

Estimates of intake based only on consumption of water-based drinks and national levels of use were submitted by the United Kingdom, where the maximum level of use of quillaia extracts is 95 mg/kg, although 200 mg/kg is permitted in the European Union. The estimated mean intakes of quillaia extracts were 0.18 mg/kg bw per day, or 4% of the ADI, by adult respondents and 1.7 mg/kg bw per day, or 34% of the ADI, by child respondents. The estimated intake of quillaia extracts by adult consumers of large amounts was below the ADI, but that for children who were high consumers exceeded the ADI (5.2 mg/kg bw per day or 105% of the ADI).

Estimates of intake based only on soft drinks likely to contain the additive and national levels of use were submitted by the USA, where the maximum manufacturers’ level of use of quillaia extracts is 100 mg/kg. The estimated intakes were 0.3 mg/kg bw per day, or 6% of the ADI, for consumers at the mean level and 0.54 mg/kg bw per day, or 11% of the ADI, for consumners at the 90th percentile of consumption.

3.4 Evaluation of intake estimates

Screening by application of the budget method showed that further assessment of the intake of quillaia extracts was required. The reverse budget method indicated that up to 600 g of water-based flavoured soft drinks could be consumed by a 60-kg person, or 150 g by a 15-kg child, before the ADI of 5 mg/kg bw was exceeded, if quillaia extracts were used at a concentration of 500 mg/kg, as proposed in the draft GSFA. Intake estimates based on poundage data from the USA indicated low per capita intakes of quillaia extracts (< 1% ADI), although this type of estimate tends to result in underestimates of the intake by high consumers.

Intake estimates based on individual records in national surveys tend to provide more accurate estimates of the actual intake of food additives. The issue of the poor absorption of quillaia extracts was not considered in this evaluation. Data on food consumption submitted to the Committee indicated that consumers of large volumes of soft drinks likely to contain the additive (95th percentile) in Australia and children aged 1.5–4 years in the United Kingdom who are drink large volumes of all soft drinks (97.5th percentile) may exceed these amounts, although these may be overestimates of long-term consumption because they are derived from short-term surveys. Estimated intakes at the 95th percentile of consumption in Australia and New Zealand, based on a single 24-h recall, tend to overestimate the habitual intake of quillaia extracts by these consumers, as evidenced by the much higher reported levels of consumption at that level in those countries. In the surveys in the United Kingdom and the USA, the amounts of food consumed were averaged over a number of days (3 and 7, respectively), which would tend to decrease the reported daily consumption of all foods but in particular foods consumed occasionally (Gibney, 1999; Lambe et al., 2000).

The use of food consumption data for all water-based drinks, as in the submissions from New Zealand and the United Kingdom, would result in overestimates of the actual intake of quillaia extracts, which are used in a limited number of drinks as a foaming agent. Nevertheless, the estimated intakes based on these data and national levels of use did not exceed the ADI for the population of the United Kingdom, as quillaia extracts are permitted for use at lower maximum levels (95 mg/kg). Young children are an exception, as their relatively heavy consumption of water-based drinks and low body weight resulted in an estimated intake of quillaia extract that exceeded the ADI for consumers at the high level. This estimate is still conservative in that it was assumed that all water-based drinks contained quillaia extracts at the maximum manufacturers’ level of use. In addition, data from short-term nutritional surveys do not permit estimation of the frequency or duration of exceedence over the ADI.

The most accurate estimates of intake were those from the USA, where information on consumption of soft drinks likely to contain the additive and national levels of use were available. The estimated intakes of quillaia extracts were well below the ADI for consumers at both mean and high levels. Quillaia extracts are not currently permitted for use in Australia or New Zealand; however, were the additive to be permitted at levels of use similar to those in the USA and used in only a limited number of soft drinks (such as ginger beer, root beer, and cream soda), the estimated intake would also be below the ADI.

4. COMMENTS

Toxicological data

Studies of acute toxicity showed that quillaia extracts are less toxic when administered orally than when administered systemically. Fractions isolated from Q. saponaria differed widely in acute toxicity as well as in adjuvant activity and cholesterol-binding capacity. QS-18, the major saponin of quillaia extracts, was more acutely toxic to mice than two other saponins that were isolated and was more toxic than the extract itself when administered intradermally.

In a 90-day study, rats fed diets containing 4% quillaia extract (equivalent to 2000 mg/kg bw per day; specifications conformed to the Emulsifiers and Stabilisers in Food Regulations 1975 of the United Kingdom, but information on the actual composition of the material tested was not available) showed decreased body-weight gain, decreased relative liver weight, and increased stomach weight, with no treatment-related histological changes. The NOEL was a dietary concentration of 0.6%, equivalent to 400 mg/kg bw per day.

In a more recent 90-day study, rats were given quillaia saponins in deionized water by gavage at a dose of 1200 mg/kg bw. Severe and lethal toxic effects were observed during the study. In the surviving animals, the weights of several organs were increased, and several haematological and clinical parameters were changed. Histopathological examination showed inflammatory changes in the forestomach, larynx, trachea, and lungs.

Minor changes in body-weight gain and the relative weights of some organs were reported in lifetime studies in mice and rats given quillaia extract (with specifications conforming to the Emulsifiers and Stabilisers in Food Regulations 1975 of the United Kingdom), at dietary concentrations up to 1.5% in rats and 3% in mice. No compound-related histopathological changes were reported. The NOELs for quillaia extract in the diet were 0.5% (700 mg/kg bw per day) for mice and 1% (500 mg/kg bw per day) for rats.

The Committee noted that the differences in toxicity observed in the 90-day studies in rats treated orally, outlined above, may have been due to differences in the test material, i.e., the concentrations and types of saponins present, and/or in the method of administration, i.e., in the diet and by gavage in water.

The existing specifications for quillaia extracts were revised in order to clarify further the differences between unpurified and semi-purified extracts. As additional information on composition was determined to be necessary, the specifications were designated as tentative. Once the requested information has been received, the Committee will consider whether separate specifications for unpurified and semi-purified extracts are required.

Intake

Quillaia extracts can be used as foaming agents in soft drinks and in cocktail mixes and as emulsifiers in foods such as baked goods, candies, frozen dairy products, gelatine, and puddings. Their major food use is in soft drinks such as ginger beer, root beer, and cream soda.

A reverse budget method based on the temporary ADI of 0–5 mg/kg bw and use of quillaia extracts in soft drinks at a level of 500 mg/kg indicated that a person weighing 60 kg could consume up to 600 g of drink per day before exceeding the ADI, while a child weighing 15 kg could consume only 150 g of drink per day before exceeding the ADI. Data on food consumption submitted to the Committee indicated that consumers of soft drinks likely to contain the additive at the 95th percentile in Australia and children aged 1.5–4 years in the United Kingdom who consume soft drinks at the 97.5th percentile could exceed these amounts, although the data may overestimate long-term consumption because they are derived from short-term surveys.

Estimates of intake based on consumption of soft drinks likely to contain this food additive and the levels of use of quillaia extract in the draft GSFA were submitted by Australia and the USA. Estimates of the mean intakes of quillaia extracts by respondents in the United Kingdom were available which were based on consumption of all water-based flavoured drinks and are therefore more conservative. For Australia, the mean intakes were 3 mg/kg bw per day (60% of the ADI) for consumers on the basis of the draft GSFA level (500 mg/kg) and 7.2 mg/kg bw per day (145% of the ADI) for high consumers. For the USA, the estimated mean intakes of quillaia extracts were 1.5 mg/kg bw per day (30% of the ADI) for consumers on the basis of the draft GSFA level and 2.7 mg/kg bw per day (54% of the ADI) for consumers at the 90th percentile.

Estimates of intake based only on consumption of soft drinks likely to contain the food additive and national levels of use were submitted by the USA. The maximum level of use of quillaia extracts by manufacturers in the USA is 100 mg/kg. The estimated mean intake of quillaia extracts by consumers was 0.3 mg/kg bw per day (6% of the ADI), and that for consumers at the 90th percentile was 0.54 mg/kg bw per day (11% of the ADI). Data from the United Kingdom based on a use level by manufacturers of 95 mg/kg indicated that children who consumed soft drinks at the 97.5th percentile level had an intake of quillaia extracts of 5.2 mg/kg bw per day (105% of the ADI), but this value may be an overestimate of intake as it is based on consumption of all water-based flavoured drinks.

Use at the maximum level of 95–100 mg/day reported by the manufacturers, as in the United Kingdom and the USA, appeared to be adequate for the technological function of quillaia extracts as foaming agents in soft drinks and did not appear to result in intakes that exceed the ADI. Young children are a possible exception, but as the results of a short-term nutritional survey were used the frequency or duration of their potential exceedence of the ADI was unknown.

The Committee recommended that the Codex Committee on Food Additives and Contaminants review the use of quillaia extracts at 500 mg/kg proposed in the draft GSFA in the category 14.1.4 ‘Water based flavoured drinks’ (Annex 1, Annex 4 of reference 137).

5. EVALUATION

The Committee made the previously established ADI of 0–5 mg/kg bw for unpurified extract temporary and extended it until 2003, pending clarification of the specifications for quillaia extracts. The Committee emphasized that the temporary ADI is not applicable to the semi-purified or any other product derived from Q. saponaria or from other species of Quillaia.

The Committee will reconsider the subject when the specifications for quillaia extracts have been clarified; further studies of toxicity with specified quillaia products that reflect the nature of the product consumed by humans may be required.

6. REFERENCES

Australia–New Zealand Food Authority (2001a) Submission on estimated quillaia extract intakes to WHO on behalf of the Australian Government.

Australia–New Zealand Food Authority (2001b) Submission on estimated quillaia extract intakes to WHO on behalf of the New Zealand Government.

Codex Alimentarius Commission (2000) Report of the Thirty-second Session of the Codex Committee on Food Additives and Contaminants, Beijing, 20–24 March 2000. Rome, Food and Agriculture Organization of the United Nations, FAO document ALINORM 01/12; available from FAO or WHO.

Drake, J.J., Butterworth, K.R., Gaunt, I.F., Hooson, G., Evans, J.G. & Gangolli, S.D. (1982) Long-term toxicity study of quillaia extract in rats. Food Cosmet. Toxicol., 20, 15–23.

Efimova, T.G., Pivnenko, G.P., Koutsevich, V.A. & Sikova, N.Ya. (1966) [The action of soapbark tree Quillaia saponaria saponins on blood pressure and cholesterol content in animals.] Farm. Zh. (Kiev), 21, 45–49 (in Russian).

Food and Drug Administration (2001) Submission on estimated quillaia extract intakes to WHO on behalf of the Government of the USA.

Food Standards Agency (2001) Submission on estimated quillaia extract intakes to WHO on behalf of the Government of the United Kingdom.

Gaunt, I.F., Grasso, P. & Gangolli, S.D. (1974) Short-term toxicity of quillaia extract in rats. Food Cosmet. Toxicol., 12, 641–650.

Gebara, V.C., Petricevich, V.L., Raw, I. & da Silva, W.D. (1995) Effect of saponin from Quillaja saponaria (Molina) on antibody, tumour necrosis factor and interferon-gamma production Biotechnol. Appl. Biochem., 21, 31–37.

Gee, J.M., Price, K.R., Ridout, C.L., Johnson, I.T. & Fenwick, G.R. (1989) Effects of some purified saponins on transmural potential difference in mammalian small intestine. Toxicol. in Vitro, 3, 85–90.

Gibney, M.J. (1999) Dietary intake methods for estimating food additive intake. Regul. Toxicol. Pharmacol., 30, S31–S33.

Guo, S., Kenne, L., Lundren, L.N. Rönnberg, B. & Sundquist, B.G. (1998) Triterpenoid saponins from Quillaja saponaria. Phytochemistry, 48, 175–180.

Kawaguchi, M., Kato, T., Kamada, S. & Yahata, A. (1994) Three-month oral repeated administration toxicity study of seed saponins of Thea sinensis L. (Ryokucha saponin) in rats. Food Chem. Toxicol., 32, 431–442.

Kensil, C.R., Patel, U., Lennick, M. & Marciani, D. (1991) Separation and characterization of saponins with adjuvant activity from Quillaja saponaria molina cortex. J. Immunol., 146, 431–437.

Lambe, J., Kearney, J., Leclercq, C., Berardi, D., Zunft, H.F.J., De Henauw, S., De Volder, M., Lamberg-Allardt ,CJ.E.,. Karkkainen, M.U.M., Dunne, A. & Gibney, N.J. (2000) Enhancing the capacity of food consumption surveys of short duration to estimate long term consumer-only intakes by combination with a qualitative food frequency questionnaire. Food Addit. Contam., 17, 177–187.

Leung, A.Y. (1980) Encyclopedia of Common Natural Ingredients Used in Foods, Drugs, and Cosmetics, New York: John Wiley & Sons.

National Academy of Sciences (1989) 1987 Poundage and Technical Effects Update of Substances Added to Food, Committee on Food Additives Survey Data, Food and Nutrition Board, Washington DC.

Philips, J.E. Butterworth, K.R., Gaunt, I.F., Evans, J.C. & Grasso, P. (1979) Long-term toxicity study of quillaia extract in mice. Food Cosmet. Toxicol., 17, 23–27.

Richou, R., Lallouette, P., Jensen, R. & Belin, Cl. (1965) [Research on saponin, an adjuvant and immune stimulant] Rev. Immunol., 29, 205–219 (in French).

Rönnberg, B., Fekadu, M. & Morein, B. (1995) Adjuvant activity of non-toxic Quillaja saponaria Molina components for use in ISCOM matrix. Vaccine, 13, 1375–1382.

Rönnberg, B., Fekadu, M, Behboudi, S., Kenne, L. & Morein, B. (1997) Effects of carbohydrate modification of Quillaja saponaria Molina QH-B fraction on adjuvant activity, cholesterol-binding capacity and toxicity. Vaccine, 15, 1820–1826.

WHO (1987) Guidelines for the Study of Dietary Intakes of Chemical Contaminants (WHO Publication No. 87), Geneva, p. 54.



    See Also:
       Toxicological Abbreviations
       Quillaia extracts (WHO Food Additives Series 17)
       QUILLAIA EXTRACTS (JECFA Evaluation)