PROBLEM I . How to Choosc Foods Wisely 



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Fig. 197 This rat was fed a diet lackmg vitamin B.,. During six weeks of a diet rich in 

 vitamiji B.,, its weight increased from 6^ grains to 16^ grams. Why should several rats 

 be used in such an experime^it? Explain, (u. s. department of agriculture) 



deficiency causes drying up of the tear 

 glands and damage to the eyes. And in- 

 sufficient amounts of vitamin A in the 

 body result in the inability of the eyes 

 to produce a substance called visual pur- 

 ple; this is needed for vision in dim light. 

 Furthermore vitamin A keeps the mu- 

 cous membranes of the body normal and 

 healthy. 



The vitamin B complex. What was 

 formerly called vitamin B is really a group 

 of vitamins. The one in the group asso- 

 ciated with beriberi is now called vitamin 

 Bi or thiamin. People getting an insuf- 

 ficient amount of thiamin are easily fa- 

 tigued and have a poor appetite; this may 

 be followed by loss of weight, irrita- 

 bility, and mental depression, A defi- 

 ciency of thiamin in the diet is common. 

 The best concentrated sources of thia- 

 min are liver, wheat germ, and yeast. It 

 occurs quite abundantly in wheat, rice, 



barley, peanuts, dried beans, peas, and 

 soybeans. Unfortunately, the grains are 

 often refined before they are used. In 

 the refining process the vitamins, which 

 are in the covering of the seed and in the 

 germ, are removed. 



Niacin (formerly called nicotinic acid) 

 is another vitamin of this group. Defi- 

 ciency of niacin causes the disease known 

 as pellagra. In the United States alone 

 about 100,000 people suffer from this 

 disease. There have often been outbreaks 

 of pellagra in institutions where too strict 

 economy was practised and no fresh 

 vegetables, milk, or fruits were included 

 in the diet. A less marked deficiency 

 causes loss of appetite and a general 

 breakdown of morale. As in the case of 

 thiamin its best source is liver and yeast. 

 Other good sources are kidneys, sweet- 

 breads, milk, and cheese, as well as the 

 unrefined grains which contain thiamin. 



