Antitoxic effects of plant fiber.

An extensive series of studies have been conducted during the past 20 years indicating the beneficial effects of alfalfa and other plant fiber-containing materials in counteracting the toxic effects of a number of drugs, chemicals, and food additives when administered at high doses to animals fed highly purified, low-fiber diets (1-9). The protective factor or factors in these fiber-containing materials is distinct from any of the known nutrients. Supplements of purified cellulose in the case of a number of the above toxic agents had a moderate protective effect, but in all cases studied the protective effect of the plant fiber-containing materials was greater than could be accounted for on the basis of their cellulose content per se. These studies were initiated by the observation of Woolley and Krampitz (1) that immature mice fed a purified ration containing 5-10% glucoascorbic acid developed a severe condition characterized by failure of growth, diarrhea, subcutaneous hemorrhages, an unthrifty appearance, alopecia and death. These effects did not occur in mice fed similar doses of glucoascorbic acid in conjunction with a natural food stock ration nor in mice fed the purified diet supplemented with dried grass. Subsequent studies demonstrated that alfalfa meal when incorporated at a 10% level in the diet was similarly effective in counteracting the toxic effects of glucoascorbic acid in the mouse and that the protective effects of alfalfa meal were not due to its content of any known nutrient (2). Similar findings were also obtained in the rat (3). The protective factor or factors in alfalfa was retained in the alfalfa residue fraction (the water-washed pulp remaining after extraction of the juice). Dried alfalfa juice was devoid of activity. Dehydrated rye grass, orchard grass, wheat grass, fescue grass, and oat grass were also potent sources of the active factor or factors. Cellulose per se when incorporated in the purified, glucoascorbic acid-containing diets had a moderate protective effect in both the mouse (2) and rat (3), but its protective effect was considerably less marked than that obtained with the plant fiber-containing materials indicated above. In 1953 Chow et al. (4) reported that the nonionic surface-active agent polyoxyethylene (20) sorbitan monostearate (Tween 60) when incorporated at levels of 5% or higher in a purified, low-fiber diet induced growth retardation, diarrhea, and other toxic effects when fed to weanling rats but that such adverse effects were counteracted by the concurrent administration of bulk-forming substances. These investigators suggested that the toxic effects of Tween 60 when fed with the purified, low-fiber diet were due to the lack of sufficient residues in the ration to absorb the surface-active agent, which was irritating to the intestinal tract by virtue of its physical properties; and they cited as evidence for this hypothesis their finding that the addition of bulk-forming substances such as celluflour or agar to the diet prevented the occurrence of such toxic effects. Subsequent studies (5) indicated, however, that marked differences exist in the activity of different bulk-forming substances in counteracting the toxic effects of Tween 60 when fed with a purified, low-fiber diet. Immature mice fed a highly purified, low-fiber diet containing 7.5% Tween 60 were found to exhibit a marked