Protein ingestion study

Since the early 1970 s, research has been directed at identifying the mechanism by which the calciuria is induced. Attention was given first to the question of whether the elevated urinary calcium excretion was caused by an increase in the intestinal absorption of calcium. Results of calcium balance studies in human subjects showed that protein ingestion either had no effect on calcium absorption (4) or that the effect was insufficient to account for the calciuria (5j. Consequently, negative calcium balance is a frequent observation in human studies when high protein diets are fed, and this situation is not improved by high calcium intakes (4 ). 

Shibayama Y, Ikeda R, Motoya T, et al. St John s wort (Hypericum perforatum) induces overexpression of multidrug resistance protein 2 (MRP2) in rats a 30-day ingestion study. Food Chem Toxicol 2004 42 995-1002. 

Oral exposure to cyanide usually results from accidental, homicidal, or suicidal ingestion of cyanide salts. Sodium cyanide and potassium cyanide are the most frequently studied cyanide compounds. Copper cyanide, potassium silver cyanide, silver cyanide, and calcium cyanide are other compounds that humans could encounter through oral or dermal exposure. Cassava roots and certain fruit pits contain compounds that can be broken down to form cyanide. Cassava roots form the staple diet of some populations in Africa, Central and South America, and Asia. However, it must be noted that cassava roots are notoriously deficient in protein and other nutrients and contain many other compounds, in addition to cyanide, that could be responsible for some of the observed toxic effects. Thiocyanate is a metabolite of cyanide that is formed in the body after exposure to cyanide compounds. When possible, all oral exposures are expressed as mg CN/kg/day. 

Mechanistic studies carried out in the course of recent years indicated that sodium saccharin may be involved in the formation of specific proteins occurring in rat urine which may contribute to the formation of bladder tumours. Most scientists and regulatory authorities now share the view that the incidence of bladder tumours in male rats after saccharin ingestion is species-specific and therefore probably without any significance for humans. Accordingly, the former temporaiy ADI of 0-2.5 mg/kg of body weight has been raised to 0-5 mg/kg by JECFA21 and the SCF.22... 

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