Nutrients and Disease Management
Nutrients are required to drive the basic physiological activities that sustain life. All innate cellular functions, defenses, and repair systems require a continuous supply of nutrients provided by nutrient reserves to make up the shortfall as dietary intakes fluctuate due to disease and other external causes. Among the critical nutrient-dependent cellular defenses are free radical and cellular antioxidant enzymes, acute inflammatory responses, phagocytic and bactericidal activity, lymphocyte activation and proliferation, humoral and cell-mediated immunity, and the initiation and promotion of the coagulation cascade. Additional defensive roles supported by nutrients involve protein synthesis, reversal and repair of DNA and chromosomal damage, integrity of immune cell structure and function, and a whole host of other activities at the molecular level.
If nutrient intakes are not sufficient to adequately support these basic physiological activities, adaptive mechanisms are triggered to conserve the available nutrient supply. Among these mechanisms are increased efficiency of intestinal absorption, enhanced renal re-absorption, adjustment of metabolic rate, and a compensatory shift to ancillary pathways that minimize nutrient demand. Although effective as temporary corrective measures, these adaptive responses will begin to lose effectiveness over time if inadequate intakes are not corrected.
Nutrient deficiencies may be classified as absolute or relative. Absolute deficiencies are caused by chronic inadequate consumption of nutrients that eventually results in depletion of reserves. Depleted nutrient reserves leave cells vulnerable to daily fluctuations in nutrient intakes or to sudden increases in demand that occur with unintended exposure to environmental stressors such as pathogens, chemical irritants, and oxygen free radicals, or to cellular injury from infection or trauma. Relative deficiencies can occur even if nutrients are consumed in adequate amounts to meet basic physiological requirements and maintain reserves, when these intakes are not sufficient to satisfy increases in metabolic demand.
Nutrient requirements in the presence of disease are considerably higher than those that have been established to prevent the symptoms of the classic deficiency diseases. These requirements can increase incrementally by as much as 10 to more than 100 times the usual amounts. At these levels of intake, the roles for most nutrients are expanded to include functions that are not typically observed at physiological intakes. The higher requirements for nutrients in disease are needed to support the accelerated rate of metabolic activity that cellular systems demand in order to reduce the potential for permanent damage from the pathophysiological processes associated with the disease.