COPING WITH ACUTE STRESS REACTIONS BY PLE NTIFUL ORAL MAGNESIUM SUPPLY

''Plentiful'' oral magnesium (Mg) supply is defined as amounts that cl early exceed the Recommended Dietary Allowances (RDA), respectively an imals' requirement. The standard laboratory chow of rats usually conta ins already plentiful Mg (4 to 5 times the requirement) whereas human diets scarcely meet the RDA. Hence plentiful Mg supply is achieved in man only when Mg supplements are given additionally. Plentiful Mg incr eases plasma-Mg levels to upper normal levels or above, with saturated bone Mg pools and increased urinary Mg excretion. Recent experimental data show that increased serum-Mg penetrates blood-brain and blood-li quor barriers to a small, but biologically significant extent. This ex plains central-nervous, probably tranquillizing effects which could be partly mediated through a block of the voltage-dependent NMDA-channel s by Mg2+. Stress reactions, mediated by increased levels of exogeneou s or endogeneous levels of excitatory amino acids like glutamate or as partate, might thus be attenuated by plentiful Mg supply. In addition plentiful Mg supply has been shown to exert beneficial systemic periph eral effects. Glycogen depletion of the liver and also of skeletal mus cles during catecholamine-mediated stress reactions is of central path ophysiological importance triggering adverse and exhausting chain reac tions. Plentiful oral Mg supply protects glycogen stores and hence att enuates the release of stress hormones and their adverse effects on ho rmonal and metabolic parameters. Plentiful anti Mg supply is generally safe and therefore recommended before undergoing stressful events. Ho wever, supplementation has to be started long enough before such event s.