VITAMINS AND THEIR USES 333 



ganic nutrients are (8), (9) or (10), and 



(11). Proteins contain (12) (13), the 



" building stones " of the body. If a protein contains the 



(14) (15) essential for (16), it is said to be a 



(17) protein (18) are essential to a diet because 



they act as (19) of various bodily (20). 



PROBLEM n. WHAT DO VITAMINS DO FOR US? 



Laboratory Exercise. Make a list of all foods which you have eaten 

 within the last 24 hours. Compare j r our list with the table on pages 336- 

 337 to see if you are eating foods that give you the best sources of vitamins 



A, B, C, and D. 



Vitamins and their uses. Most wonderful of all our foods are 

 the regulating substances, vitamins. While little is known of their 

 chemical composition, a good deal has been learned of what 

 they do, or, rather, of what effect their absence will cause. These 

 health-regulating substances are known as Vitamins A, B, C, D, 

 E, and G. A glance at the diagram (pag3 334) shows that vitamin A, 

 soluble in fats, is found abundantly in milk, egg yolk, cod-liver oil, 

 and butter, and in lesser amounts in certain vegetables. Vitamin 



B, soluble in water, is found in the outer layers of many cereals 

 and fruit, in milk, and in fresh yeast. Vitamin C is found in fresh 

 vegetables and in citrus fruits. Vitamin D is found in cod-liver 

 oil, milk, and coconuts. Vitamin E is found in meat, lettuce, 

 yellow corn, whole wheat, and milk fat. Vitamin G is found in 

 milk, yeast, and some meats. Vitamins appear to be largely of 

 plant origin and in many cases are destroyed or their value is 

 lessened by heat, although some stand high temperatures, as in 

 canned tomatoes or boiled potatoes. 



So much for what they are. Now what do they do ? Rats fed 

 on a diet lacking vitamin A are stunted in growth and develop an 

 eye disease called xerophthalmia, which may result in permanent 

 blindness. It has been known for a great many years that if 

 explorers or sailors were deprived of fresh food, they suffered from 

 the disease called scurvy. During the World War more than 

 one war vessel was interned in a neutral port, not because of 

 the guns of enemy ships, but because the crew suffered from this 



