Vitamin in animal and human nutrition

McDowell. L.R. Vitamins in Animal and Human Nutrition. 2nd Edition. Iowa State University Press, Antes, 1A. 2000. 

McDowell LR., 2000. Vitamins in animal and human nutrition. 2nd ed. Iowa State University Press, Ames, Iowa, USA. 

Note Calcium is an essential component of bones, teeth, shells, and plant structures. It occurs in milk in trace amounts and is necessary in animal and human nutrition. Vitamin D aids in the deposition of calcium in bones. 

It is unusual for single-nutrient deficiencies to occur under natural conditions, apart from those conditions associated with inborn errors in metabolism or those with unusual ecological circumstances. The latter, for example, may occur when soils are selectively nutrient-deficient, such as for iodine or some other trace minerals, and when access to an external food supply is limited. Consideration of vitamin A in animal and human nutrition, therefore, must be viewed in relation to the balance in diets of other nutrients with which it interacts directly or indirectly. 

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