BIOLOGICAL SIGNIFICANCE OF VITAMINS 



of the enzyme molecule and we need to know more about the rest of 

 the molecule. Perhaps proper exercise with limited amounts of vita- 

 mins may be more conducive to rigorous enzyme systems than the 

 consumption of vitamin cocktails while reclining in an easy chair. 

 Studies on the enzyme systems will help to relate nutrition to such 

 important problems as resistance to infection, prevention of cancer, and 

 resistance to the process of aging. Biochemists have learned how to 

 disorganize cells into parts, but greater integration of the parts into a 

 whole must be attained. 



More attention also must be paid to the bacteria in the intes- 

 tinal tract. Bacteriologists have studied the bacteria in soils, in milk, 

 in foods, and in disease, but have largely disregarded the bacteria of our 

 intestines. There are still nutritional disturbances which must be re- 

 lated indirectly to the changes in the digestive tract.- Very recently, 

 a most interesting report was presented on the nutritional status of 

 about 800 individuals living in Newfoundland: certain symptoms 

 observed were ascribed to riboflavin and niacin deficiencies, and yet a 

 rough estimate indicated that the intake of these vitamins was not 

 seriously inadequate. I believe some of the changes, at least, are due to 

 a lack of as yet unknown vitamins which were not synthesized in suffi- 

 cient amounts because of the type of dietary regime. Pellagra has 

 always been associated with a large consumption of corn. Preliminary 

 evidence in our laboratory indicates that an extensive corn intake 

 may adversely affect the synthesis of vitamins in the intestinal tract, an 

 effect which is overcome by high levels of nicotinic acid. High levels 

 of protein also have a counteracting effect, which may explain why 

 milk has been found to have antipellagra activity although it is known 

 to contain little nicotinic acid. 



Intestinal synthesis is not limited to the production of the vita- 

 mins which are the last to be discovered. Obviously, the degree of 

 synthesis in the intestine must be less in the case of the older vitamins, 

 or we would have had more difficulty in producing the deficiency state 

 of these vitamins. Some time ago, we showed that the fat content of 

 the diet had a marked effect on the riboflavin requirement of the rat. 

 Diets which contained dextrin and low levels of ribofla\'in produced a 

 much more severe riboflavin deficiency when a large jjortion of the 

 dextrin was isocalorically replaced by fat. Later work has shown that 

 this effect is direcdy dependent upon a decreased synthesis of riboflavin 



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