Physiological Availability of the Vitamins

Abstract

In vitro tests have indicated that various fish products intended for direct human consumption contain a thiaminase which destroys thiamine in a static test system. Rapid and complete destruction of the vitamin occurred in vitro during incubation of food mixtures containing added thiaminase, as present in raw clams. More than eight times the minimal daily requirement of thiamine was destroyed simply in preparing a homogeneous mash of a daily ration to which both clams and thiamine had been added. The results of the human availability study indicate that an appreciable destruction of thiamine (about 50%) occurs in the gastrointestinal tract following the concomitant ingestion of raw clams. Because other fish products are also consumed in a raw or partially cooked state by man, this finding warrants consideration of the anti-thiamine principle in fish products as a possible conditioning factor in malnutrition. The application of the thiaminase in clams to vitamin B₁ methodology, both biological and chemical, has been discussed.