Immature male rats were fed a purified, low-fiber diet to which were added supplements of 2% sodium cyclamate, 2% FD&C Red No. 2 and 4% polyoxyethylene (20) sorbitan monostearate individually or in combination. Whereas supplements of any one of the three food additives indicated above had little if any deleterious effect, combined supplements of sodium cyclamate and FDK Red No. 2 resulted in a marked retardation in weight increment, an unthrifty appearance of the fur, alopecia and extensive diarrhea with watery and mushy stools Concurrent administration of all three food additives indicated above resulted in a further retardation in weight increment and death of all test animals within an experimental period of 14 days. The deleterious effects obtained on the latter diet could be largely counteracted by the concurrent administration of various dietary fiber-containing materials. Blond psyllium seed powder was particularly potent in this regard. The protective factor or factors therein was distinct from any of the known nutrients and from cellulose per se.