Paralysis, Chastek

A peculiarity of thiamine is that the vitamin can easily become inactivated. An early instance was seen in 1941 when commercially reared mink became paralyzed (Chastek paralysis), a disorder which could be cured by giving the animals thiamine. The problem was traced to their having been fed fish that had partially decomposed. Later work showed that in decayed fish a microbial enzyme had been released, thiaminase, which destroyed the thiamine normally present in the food. A rather different process occurs when horses or cows are allowed to graze on bracken. This contains a protein which binds to thiamine, so reducing its availability. Once again the condition can be treated by administering the vitamin. 

In people whose thiamin intake is marginal, colonization of the gastrointestinal tract with thiaminolytic microorganisms may be a factor in the development of beriberi. The thiaminases present in raw fish can result in so-called Chastek paralysis of foxes and mink, as a result of destruction of thiamin, and may be important in parts of the world where much of the apparent thiamin intake is from fish that is eaten raw or fermented. The polyphenols and thiami-nase in bracken fern can cause thiamin deficiency (blind staggers) in horses, and tannic acid in tea and betel nut have been associated with human thiamin deficiency. 

Haff disease appeared to be the human equivalent of Chastek paralysis, which affects mink and fox. Hence, it was concluded that it was caused by eating large quantities of inadequately cooked thiamineise-containing fish with the enzyme thiaminase inactivating the thiamin molecule, resulting in a thiamin deficiency. 

ANTITHIAMIN FACTORS IN FOOD. Certain raw fish and seafood—particularly carp, herring, clams, and shrimp— contain the enzyme thiaminase, which inactivates the thiamin molecule by splitting it into two parts. This effect has been seen in mink and fox fed 10 to 25% levels of certain raw fish, giving rise to a thiamin deficiency disease known as Chastek paralysis. This action can be prevented by cooking the fish prior to feeding, thereby destroying the thiaminase. Of course, humans seldom eat sufficient thiaminase-contain-ing raw fish or seafood to produce a thiamin deficiency. 

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