The detenmnation of optimal nutritional status has traditionally been based upon generalized parameters such as weight gain and body fat levels. Vitamin and mineral requirements were often related to the intakes needed to prevent overt signs of deficiency diseases such as beriberi or scurvy. However, in the past decade or so, there have been intensive investigations to determine the subtle changes in physiological functions associated with marginal micronutrient intakes. There is a growing consensus that immune system activities are very sensitive indicators of micronutrient status. During...

Intuitively, we realize that animals that are well fed and well cared for are healthier than animals that are not well fed or well cared for. Although nutritionists have long been concerned with minimum nutrient requirements for maximal growth rate and maintenance, it has been only recently that investiagators have begun to look at the nutritional requirements that provide optimal health. The increasingly sophisticated methods of immunology have allowed investigators to define indicators of resistance to disease such as cell mediated immunity, lymphocyte functions, and macrophage functions....