SUBCHRONIC ORAL TOXICITY STUDY WITH REGULAR AND ENZYMATICALLY DEPOLYMERIZED SODIUM CARBOXYMETHYLCELLULOSE IN RATS

Enzymatically depolymerized sodium carboxymethylcellulose (CMC-ENZ) is a new functional food ingredient which has a lower molecular weight a nd viscosity than regular sodium carboxymethylcellulose (CMC). Both co mpounds are known not to be absorbed to a significant extent, and the human safety of CMC as a thickening agent and stabilizer in food is we ll established. In the present study, the subchronic oral toxicity of CMC-ENZ was examined and compared with that of CMC in Wistar rats. Sev en groups of 20 rats/sex were fed diets with 0 (controls), 2.5, 5 and 10% CMC and 2.5, 5 and 10% CMC-ENZ for a 3-month period. There was onl y one death that was unrelated to the treatment. Water intake, urine p roduction and urinary sodium excretion increased with increasing doses of CMC and CMC-ENZ due to their sodium content of about 7-8%. The tre atment-related occurrence of diarrhoea and caecal enlargement in the m id- and high-dose groups, a slight increase of plasma alkaline phospha tase, and increased urinary calcium and citrate excretions were consid ered to be generic effects that typically are observed in rodent studi es with low digestible carbohydrates. The increased occurrence of neph rocalcinosis and hyperplasia of the urothelial epithelium in some of t he treated groups was interpreted as an indirect consequence of a more alkaline urine coupled with an increased calcium excretion. As the fr equency and severity of all these changes did not differ between corre sponding CMC and CMC-ENZ dose groups, it is concluded that the two pro ducts have a similar toxicological profile.