NUTRITIONAL EFFECTS 



667 



Our understanding of the means by which 

 hormones exert their effects is relatively 

 slight, as is our knowledge of the biochemi- 

 cal mechanisms by w^hich supplements and 

 deficiencies of vitamins and amino acids 

 influence hormone action. Nevertheless, 

 support for the statement that modifications 

 of nutrition influence endocrine gland se- 

 cretions or hormone action on distant tar- 

 get organs or tissues is provided by an 

 enumeration of a few basic cell components 

 requiring proteins, lipids, and vitamins. 

 (1) Proteins combine with lipids to form 

 lipoproteins which are essential features 

 of the internal and external cellular mem- 

 branes and interfaces. Hormones, as well as 

 nutrition, influence cell membranes and 

 therefore cell transport is affected. It is well 

 known that hormones influence electrolyte 

 and carbohydrate transfer and recently an 

 endocrine control of amino acid transport 

 was demonstrated (Noall, Riggs, Walker 

 and Christensen, 1957). The effect of modi- 

 fications of nutrition on the capacity of hor- 

 mones to influence cell transport must await 

 study. (2) Enzymes are proteins with chem- 

 ically active surfaces and often include non- 

 protein groups such as vitamins. Nutritional 

 and hormonal changes cause alterations in 

 enzyme concentrations (Knox, Auerbach 

 and Lin, 1956). Vitamin, mineral, and fat 

 deficiencies favor a decrease in enzymes, 

 whereas protein deficiencies have varied ef- 

 fects (Van Pilsum, Speyer and Samuels, 

 1957). Enzyme changes caused by hormones 

 appear to be a consequence of metabolic 

 adaptations. The importance of a nutri- 

 tional base on which a hormone can express 

 an effect on the enzymes of the reproductive 

 organs can only be determined after further 

 data have been obtained. (3) Proteins com- 

 bined with nucleic acids become nucleo- 

 proteins, some of which are organized in the 

 cytoplasm and may be templates for cellu- 

 lar protein synthesis. Other nucleoproteins 

 are contained in the nucleus. Nutrition and 

 hormones influence tissue nucleoproteins 

 but studies involving the reproductive or- 

 gans are few. How^ever, one possible cause 

 of human infertility is low desoxyribose 

 nucleic acid in the sperm ("Weir and Leuch- 

 tenberger, 1957). 



Proteins are characteristic components of 



tissues and hypophyseal hormones are pro- 

 tein in nature; also the major portion of 

 gonadal dry weight is protein. Such being 

 the case, it is important to appreciate that 

 the protein composition of the body is in 

 a dynamic state and that proteins from the 

 tissues and from the diet contribute to a 

 common metabolic pool of nitrogen. This 

 metabolic pool contains amino acids which 

 may be withdrawn for rebuilding tissue 

 protein and for the formation of new protein 

 for growth. Obviously, the character of the 

 metabolic pool of nitrogen reflects dietary 

 protein level and quality. A food protein 

 which is deficient in one or more amino 

 acids will restrict tissue protein synthesis. 

 Hormones also influence the metabolic pool 

 by affecting appetite as well as absorption, 

 utilization, and excretion of foods, and thus 

 hormones could accentuate the effect of a 

 poor diet, or create demands beyond those 

 normally met by an adequate diet. In ad- 

 dition a study of the tissues and organs of 

 the body reveals that contributions to the 

 metabolic pool are not uniform, thus one 

 tissue or organ may be maintained at the 

 expense of another. In protein deprivation 

 in adults the liver quickly contributes in- 

 creased amounts of nitrogen to the metabolic 

 pool whereas the testis does not. On the 

 other hand, protein contributions to the 

 nitrogen pool by the hypophysis, and the 

 amino acid withdrawals needed for hormone 

 synthesis, are unknown. Data suggesting 

 that the addition of specific nutrients to 

 diets improves hypophyseal hormone syn- 

 thesis have been presented (Leathem, 

 1958a). 



In 1939 jNIason rightfully emphasized the 

 need for vitamins in reproduction. Since 

 then, much additional knowledge has been 

 obtained. Vitamins of the B complex have 

 been more clearly identified and a better 

 understanding of their function has been 

 gained. Thiamine is important for carbo- 

 hydrate metabolism, pyridoxine for fat me- 

 tabolism, and the conversion of tryptophan 

 to nicotinic acid, and vitamin B12 may be 

 involved in protein synthesis. In addition, 

 vitamins have been found to serve as co- 

 enzymes, and folic acid to be important for 

 estrogen action on the uterus. Tliosr. and 



