A review of the studies of the safety of polydextrose in food

Polydextrose (CAS no. 68424-04-4) is a water-soluble polymer of glucose tha t provides to foods the bulk and texture of sucrose. There are two main for ms of polydextrose, an acidic form (PD-A) and a neutralized potassium salt (PD-N). Polydextrose is resistant to mammalian metabolic and microbial dege neration, rendering it both low in caloric value and non-cariogenic. Little polydextrose is absorbed intact although some is metabolized by caecal/col onic bacteria. At high enough levels of ingestion, this bacterial metabolis m results in flatus, bloating, loose stools and ultimately a frank diarrhoe a. Microbial metabolism also produces some volatile fa;tp acids that are ab sorbed by the animal and have calorigenic value. The species and dose thres hold for persistent loose stools/watery diarrhoea determines the degree of electrolyte loss by the animal. In the dog, an obligate carnivore, sodium-s paring activity by the kidney and concomitant and obligatory calcium reupta ke result in a well-defined aetiology of hypercalcaemia and subsequent neph rocalcinosis, particularly for PD-N. Of the species tested, the dog was the most sensitive to this carbohydrate with a no-effect level of 2000 mg/kg b ody weight/day. Omnivores, including the rat, mouse and monkey, have a no-e ffect level ranging from 2500 to 10,000 mg/kg body weight/day. No toxicity has been demonstrated in man, although the dose for laxation (to be disting uished from diarrhoea) is approximately 90 g/day (v. sorbitol at 70 g/day). Polydextrose did not show any reproductive toxicity, teratology, carcinoge nesis, mutagenicity or genotoxicity. Polydextrose has been approved for foo d additive use (21 CFR 172.841) in the US, and an "ADI not specified" by th e Joint WHO/FAO Expert Committee on Food Additives (JECFA, 1987). It has be en approved in over 50 countries around the world and has been used extensi vely in the diet for over 15 years. Specification monographs are published in the Food Chemicals Codex (FCC) (NAS, 1996) and the FAO Compendium (JECFA , 1995). This review provides an overview of the studies and salient data, not previously reported in the scientific literature. which had been submit ted to regulatory agencies in support of these approvals. (C) 1999 Elsevier Science Ltd. All rights reserved.