ACETYLATED DISTARCH ADIPATE Explanation This substance was evaluated for acceptable daily intake for man (ADI) by the Joint FAO/WHO Expert Committee on Food Additives in 1969 and 1971 (see Annex I, Refs. 20 and 27). A toxicological monograph was issued in 1974 (see Annex I, Ref. 33). 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. Introduction Modification is carried out by the use of 8% acetic anhydride and a maximum of 0.12% adipic acid, the latter acting as cross-linking agent. The maximum number of acetyl groups introduced is 2.5%. The number of adipic cross-links does not exceed more than 1 in about 1000 glucopyranose units, or not more than 0.09% adipyl groups introduced in the starch. BIOLOGICAL DATA BIOCHEMICAL ASPECTS In vitro studies with pancreatin have shown that only the acetate ester bond splits easily while the adipic acid ester linkages are not attacked. No free adipic acid could be demonstrated in the hydrolysate (Morgareidge, 1959a). In vitro digestion with amyloglucosidase of acetylated distarch adipate showed a digestibility of 98.3% (Kruger, 1970). The metabolic fate of adipate-modified starches was investigated in male rats in vivo using adipic acid labelled at Cl and C6 with C14. The rate of appearance of 14CO2 was compared between labelled adipic acid and starch modified with 1,6- C14 adipic acid. Starch adipate is absorbed and/or metabolized more slowly than adipic acid, as evidenced by the delayed appearance of 14CO2 in the respired air. 99.3% of the C14 activity of the free adipic acid was recovered in the respired air; 5.8% appeared in the urine while none was detected in the faeces in the gastrointestinal tract or in the carcass. 70.5% of the C14 activity of the esterified adipic acid appeared in the respired air and 7.2% in the urine; 24.5% was found in the faeces. No activity appeared in the carcass (Morgareidge, 1959b). The caloric equivalent of the modified starch was determined in groups of 10 male rats fed for 28 days on a basal diet containing either 1.5 or 3.0 g of starch supplements. The modified starch had been treated with 0.2% adipic anhydride and 5.5% acetic anhydride. Native starch was used as control. Caloric values were determined from a dose/response curve obtained by the use of 0, 0.75, 1.5, 3.0 and 4.5 g of sucrose supplements equivalent to 0, 3, 6, 12 and 18 calories per day. There was no difference in caloric value between the modified and unmodified starches (Oser, 1961). TOXICOLOGICAL STUDIES Special studies on kidney lesions associated with dietary modified starch Hamster Groups of 10 male and 10 female Syrian golden hamsters, weighing 30-40 g, were fed a diet containing either 30% acetylated distarch adipate or 30% untreated starch for 30 days. Hamsters fed the test diet exhibited a reduction in average daily weight gain, compared to control animals, but the average daily test diet intake was also reduced. Comparison of feed consumption to corresponding weight gain did not indicate a significant difference in efficiency of utilization of the test and control diets. No treatment-related differences were noted in haematology, clinical chemistry or urinalysis data. No treatment-related lesions were evident in histological sections from liver and kidney (Newberne & Buttolph, 1977). Groups of 8 male and 12 female Syrian golden hamsters (weanlings) were fed a diet containing either 30% acetylated distarch adipate or 30% untreated starch for periods of either 30 or 60 days. The diets contained Ca, 0.51%, P, 0.4% and Mg levels ranging from 0.017% to 0.210% (0.6% is the normal requirement). Ten animals/group (6 female, 4 male) were sacrificed at day 30 and the remaining animals at day 60. At autopsy, animals on test diet showed increased caecal weight. No weight difference was observed for liver and kidney. Haematological studies showed no compound-related effects. Histological sections from kidney demonstrated an increased incidence of lesions (cortical scarring and tubular dilatation) associated with consumption of the test diet for 30 or 60 days. These kidney lesions did not appear if the test diet was supplemented with magnesium. Kidneys from hamsters fed acetylated distarch adipate were analysed for calcium and magnesium content by neutron activation analysis. No correlation was evident between kidney magnesium levels and either dietary magnesium levels or severity of renal lesions. However, a suggestive correlation existed between kidney calcium levels and severity of lesions (Newberne & Buttolph, 1979a). Rat Weanling Sprague-Dawley rats were distributed into groups of 6 or 12 males or females and fed a test diet containing 30% acetylated distarch adipate + 10% unmodified starch or a control diet, consisting of 40% unmodified starch, for 30 days. The mineral mix in the diet was held constant, but Ca, P and Mg were varied according to design, which permitted manipulating the Ca/P content and ratios from 1.5/1.36-0.5/0.56 to 0.1/0.76-1.6/0.26. The level of magnesium was 0.06% (the required intake), but in 1 group with Ca/P Ca/P ratio of 1.5/1.36 was lowered to 0.02% and in another group raised to 0.2%. One control group of Ca/P ratio of 0.5/0.56 had a magnesium level of 0.04%. A total of 9 different groups were used in the study. Serum biochemistry and urinalysis were carried out on the test animals. At low dietary calcium/phosphate ratios, females on test diet experienced slightly elevated serum calcium. Serum magnesium tended to be depressed by low dietary calcium/phosphate ratios and by low dietary magnesium levels (0.02%), but was not affected by the test diet. Urinary magnesium levels tended to be increased in animals on the test diet. Fluctuations in other urinary electrolytes were affected by dietary calcium/phosphate ratios and magnesium content, but not by the test diet. Significant fluctuations occurred in urinary creatinine levels, but these fluctuations did not appear to be treatment related. At autopsy, organ weights showed no treatment-related effects except for the caecum, which was enlarged. Histopathological evaluation of kidney sections from control and test animals revealed a characteristic lesion consisting of mineral deposits in tubules at the corticomedullary junction. This lesion was not considered to be morphologically comparable to the "pelvic nephrocalcinosis" lesions previously reported in other laboratories. It was more common in females than in males. A high calcium/phosphorus ratio (5.8/1) and low phosphorus level (0.26%) in the diet prevented mineralization in kidneys of animals on test diet and significantly reduced this lesion in controls. There were no other compound-related effects. Histological examination of bone tissue and parathyroid glands showed no effect even with relatively severely imbalanced Ca/P ratios (Newberne & Buttloph, 1980). Groups of 25 female Sprague-Dawley rats were fed diets containing either 30% acetylated distarch phosphate or 30% unmodified starch (control) in a 1-year study with weanling rats (Experiment I) and a separate 9-month study utilizing 9-month-old rats (Experiment II). The calcium concentration in the diet was ca. 1%, phosphorus ca. 0.8% and magnesium ca. 0.15%. Urinary calcium concentration and total daily output were significantly increased in animals on the test diet (Experiments I and II), but only minor differences were seen in phosphorus, oxalate, magnesium and creatinine excretion. No significant effects were observed on body weight, food consumption, urine volume, urine pH and crystal content or faecal mineral content in animals on the test diet. At autopsy, caecal enlargement was present in treated animals, but no other treatment-related effects on relative organ weights were observed. No treatment-related histopathological effects were observed in the uterus or lower urinary tract, liver, parathyroid, caecum or ovaries in either experiment. Histological examination of kidney sections demonstrated the presence of treatment-related pelvic nephrocalcinosis. An apparent correlation was observed between the increased incidence of pelvic nephrocalcinosis, increased accumulation of calcium in the kidney, and increased urinary excretion of calcium. Residues of calcium in kidney tissue were significantly higher in test groups than in controls (Hodgkinson et al., 1981). Roe (1979) has conducted an extensive review of mineral deposition in the renal pelvis of rats and concluded that pelvic nephrocalcinosis, corticomedullary nephrocalcinosis, acute tubular nephropathy, and calculus formation are manifestations of mineral imbalance and are of relatively common occurrence in untreated laboratory rats (particularly older animals). Special studies on reproduction Rat Groups of 10 male and 10 female rats, Sprague-Dawley-derived, were selected at random from a concurrent 2-year chronic toxicity study and, 6 weeks after weaning, mated to produce F1a and F1b litters. Test animals were maintained on a diet of 62% acetylated distarch adipate, while controls received 62% unmodified starch in their diet. After breeding was complete, parents were returned to the chronic study while 10 male and 10 female rats from the F1b litter were bred to produce F2a and F2b litters. A similar process was used to obtain F3a and F3b litters. In each generation, litters from the first mating were sacrificed at weaning and, from the second mating, 6 weeks after weaning, except for the 10 males and 10 females selected for breeding. Pre-weaning deaths were significantly elevated in offspring from F2b litters for both control and test animals compared to the previous generation, but were within normal limits for the strain. The remaining test parameters (litter size, incidence of stillbirths, sex ratio at weaning and pre-weaning growth) were similar in treated and control animals. Histological sections taken from principal organs of F3b rats reportedly did not reveal evidence of anomalies. No detailed information from the histopathological examinations was provided (Truhaut et al., 1979). Short-term studies Rat A 90-day feeding study was carried out in groups of 15 male and 10 female rats at a dietary level of 50% modified or unmodified starch. The growth rate of males was significantly lower in the test group and the full and empty caecal weights of both sexes were significantly greater in rats fed the treated starch. All rats survived the test period and no differences were observed between the groups with respect to liver and kidney weights, haematology, blood chemistry, urinalysis, gross and histopathology. The modified starch used had been treated with 0.12% adipic acid and 10.5% acetic anhydride resulting in 3.1% of acetyl groups being present (Oser, 1964). Groups of 15 male and 15 female weanling albino rats, FDRL strain, were fed diets containing either 50% acetylated distarch adipate or, for control diet, 50% thin-boiling starch for 90 days. Treated males suffered a significantly reduced growth rate, which was paralleled by reductions in food intake and efficiency of utilization. Relative weights of caeca, empty or full, were higher in both sexes of the test group compared to control weights. No treatment-related changes were observed in relative weights of liver and kidneys, or in haematology or blood chemistry analyses. However, female rats on the test diet experienced alkaline urine relative to control at week 6 of the study. Histological sections of liver, spleen, stomach, small and large intestine, caecum, pancreas, kidneys, bladder, adrenals, gonads, thyroid, thymus, salivary gland, lymph nodes, heart, lungs, bone marrow and muscle were taken from 5 female and 5 male animals of control and test groups, and liver and kidney sections from all animals. No treatment-related adverse effects were observed, but 6 control females and 3 test females had calcification at the corticomedullary junction (Oser, 1964). Long-term studies Rat Rats, Sprague-Dawley derived, 4-5 weeks old, were distributed in groups of 30 males and 30 females and fed a cooked test diet containing 62% acetylated distarch adipate and a control diet of 62% unmodified starch for 2 years. Significant reductions in growth occurred in treated animals, particularly in females. These differences could not be attributed to reduced food intake, because consumption of modified starch and control diets was comparable. The 2-year survival rate in treated animals (60%) was slightly higher than in control animals (52%). Haematology and serum clinical chemistry tests from treated and control animals were within normal range, with the exception of SGOT which was elevated in test animals. At autopsy, adipose deposits were much less extensive in treated rats than in controls, which could account for the reduced weights of the test animals. Skeletal growth, as demonstrated by femur measurements, was similar in test and control animals. Statistically significant treatment-related variations occurred in absolute organ weights relative to controls. However, relative to body weight, significant treatment-related differences in organ weights were rare. Because no treatment-related changes could be detected microscopically, the variations in organ weight were considered to be incidental. Histological examination of tissues from test and control animals showed no significant differences between the groups for either non- tumorous lesions or tumours. In the case of the kidney, hyperplasia of the kidney urothelium, sometimes accompanied by calcification, was observed in both control and test groups, but neither the incidence nor severity of these effects were considered by the authors to be treatment related. However, independent reviewers of the data concluded that in female rats, the incidence of epithelial hyperplasia was greater in the rats fed modified starch (Truhaut et al., 1979). Comments A study of 14C-labelled starch adipate in the rat showed that the adipic acid moiety entered the metabolic pool more slowly but followed the normal pathways for free adipic acid. No retention of label was found in the carcass. The previous short-term feeding studies with rats at a high dietary level showed no significant pathological changes with the exception of measured caecal weight. The available evidence for modified starches as a group suggests that caecal enlargement without associated histopathological changes is without toxicological significance. The observed decrease in growth rate with a high dietary level was considered to be due to nutritional imbalance. However, recent studies with the rat and hamster have shown that high dietary levels (30%) of acetylated distarch adipate result in an increased incidence of renal lesions under various dietary conditions. The occurrence of renal mineralization has been the subject of special studies on the rate of mineral imbalance in the development of this lesion. These lesions were associated with the Ca/P ratio in the diet, as well as the presence of adequate magnesium. Changing the Ca/P ratio (particularly lowering the phosphate level), and raising the level of Mg in the diet resulted in a marked decrease or elimination of the lesion. A multigeneration reproduction study in the rat did not show any significant effect on reproductive performance. In the lifetime study in the rat, in which the diet contained 62% cooked acetylated distarch adipate, the only significant compound-related effects were a decrease in body weight and the occurrence of renal lesions (epithelial hyperplasia). EVALUATION Estimate of acceptable daily intake for man Not specified.* * The statement "ADI not specified" means that, on the basis of the available data (toxicological, biochemical, and other), the total daily intake of the substance, arising from its use or uses at the levels necessary to achieve the desired effect and from its acceptable background in food, does not, in the opinion of the Committee, represent a hazard to health. For this reason, and for the reasons stated in individual evaluations, the establishment of an acceptable daily intake (ADI) in mg/kg bw is not deemed necessary. REFERENCES Hodgkinson, A. et al. (1981) A comparison of the effects on mineral metabolism of diets containing waxy maize starch, either of two chemically-modified waxy maize starches, or lactose. Unpublished report from the General Infirmary, Leeds, and from the Medical School, University of Leeds Kruger, L. (1970) Unpublished reports Nos. 405 & 406, submitted by National Starch and Chemical Corporation Morgareidge, K. (1959a) Unpublished report No. 78522 of Food and Drug Research Laboratories, Inc., submitted by National Starch and Chemical Corporation Morgareidge, K. (1959b) Unpublished report No. 79408 of Food and Drug Research Laboratories, Inc., submitted by National Starch and Chemical Corporation Newberne, P. M. & Buttolph, M. L. (1977) A preliminary report of a thirty-day study in hamsters fed modified starch. Unpublished report from Massachusetts Institute of Technology, submitted to the World Health Organization by the US Food and Drug Administration, 1982 Newberne, P. M. & Buttolph, M. L. (1979a) Final report. Review and conclusions of hamster studies with modified food starch. Study No. 78-4. Unpublished report from Massachusetts Institute of Technology, submitted to the World Health Organization by the US Food and Drug Administration, 1982 Newberne, P. M. & Buttolph, M. L. (1979b, rev. 1980) Final report on study No. 79-2. Metabolism studies in rats fed modified food starch. Unpublished report from Massachusetts Institute of Technology, submitted to the World Health Organization by the US Food and Drug Administration, 1982 Oser, M. (1961) Report No. 81776 of Food and Drug Research Laboratories, Inc., submitted by National Starch and Chemical Corporation Oser, B. L. (1964) Subacute (90-day) feeding studies with Amioca treated with adipic acid and acetic anhydride. Report No. 85555. Food & Drug Research Laboratories, Inc., Maspeth, NY, submitted to the World Health Organization by the US Food and Drug Administration, 1982 Roe, F. J. C. (1979) Mineral deposition in the renal pelvis of rats: A brief review. Unpublished report submitted to the World Health Organization Truhaut, R., Coquet, B., Fouillet, X., Galland, D., Guyot, D. & Long, D. (1979) Two-year oral toxicity and multigeneration studies in rats on two chemically modified maize starches, Fd. Cosmet. Toxicol., 17, 11-17
See Also: Toxicological Abbreviations Acetylated distarch adipate (FAO Nutrition Meetings Report Series 46a) Acetylated distarch adipate (WHO Food Additives Series 1) Acetylated distarch adipate (WHO Food Additives Series 5) ACETYLATED DISTARCH ADIPATE (JECFA Evaluation)