332 ANIMAL BIOCHEMISTRY 



Thiamine is lost in varying amounts when vegetables are cooked. 

 These losses vary according to cooking temperatures, types of food, and 

 the amount of cooking water thrown away before the food is served. 

 Ordinarily the loss of thiamine during cooking should not exceed 

 25 per cent if foods are cooked properly in a minimum of water. 

 Canning processes are not particularly destructive. 



In many cases thiamine losses in vegetables may be greater during 

 harvesting, handling, and storage than during actual processing in 

 the cannery. Under normal conditions, however, blanching, a short 

 heat treatment, seems to be the most important single factor affecting 

 vitamin losses in canned foods. Even canned goods must be stored at 

 relatively cool temperatures (80°F, or less) to prevent thiamine losses 

 during storage. Freezing per se has little or no effect on thiamine. 

 The greatest losses of thiamine in frozen foods occur before the 

 freezing process or during the subsequent thawing and cooking. Rapid 

 dehydration of foodstuffs at relatively low temperatures may preserve 

 over 75 per cent of the original thiamine content, whereas prolonged 

 exposure at elevated temperatures destroys much of the vitamin. 



Deficiency 



Since diets deficient in thiamine are often low in other essential 

 factors as well, uncomplicated cases of thiamine deficiency are seldom 

 encountered. Moreover, the symptoms are quite general, thus making 

 diagnosis difficult. Very complex pathologies may develop, differing 

 considerably from one individual to another. The general effect, 

 however, is development of abnormal muscle and nerve responses in 

 various parts of the body. 



As expected, the severity of symptoms corresponds to the extent 

 and duration of the deficiency. Loss of appetite and weight, weakness, 

 shortness of breath, palpitation of the heart, and muscle soreness, 

 especially of the lower parts of the legs, are early indications. Progress 

 of the disease leads to mild anesthesia, mental confusion, muscle 

 weakness and partial paralysis, loss of reflex activity, peripheral neu- 

 ritis, brain lesions, and cardiac malfunction. Ultimately, the victim 

 becomes helpless or insane and succumbs, often to heart failure. 

 Severe edema sometimes accompanies the other manifestations. Defi- 

 cient birds lose control of their neck muscles, and their heads tip 

 characteristically over on their backs. 



These various symptoms presumably result from the metabolic 

 disturbances accompanying the lack or deficiency of thiamine pyro- 

 phosphate. Oxidative metabolism is greatly impaired without the 

 coenzyme, and both pyruvic and lactic acids accumulate in large 

 amounts since utilization of pyruvate is thus blocked. Nerve cells seem 



