Effect of Dietary-Salt Restriction and Heat Acclimation on Circulatory Responsesto Upright Posture

摘要

Americans reportedly consume between 4.6 to l2.7g of salt (NaC1) per day (15). Incomparison, dietary-salt intake in Army garrison dining facilities ranges from 12 to 13g NaC1 per day (20), and consumption of three meals-ready to-eat (MRE) supplies 13.6g NaC1 per day. To promote better nutrition and health in the U.S. population, the National Research Council recommended restriction of dietary-salt intake to about 6.1g NaC1 per day (15). Numerous studies have identified several healthy populations who reside in both tropical and desert climates, but consume just 1.9 to 7g NaC1 per day (12,14,19). Additional rationale for restricting salt consumption even in hot climates is obtained from studies demonstrating the absence of either heat injury or circulatory dysfunction in individuals acclimated to heat and consuming low-salt diets (5-6g NaC1/day) (12,14,19). In contrast, daily salt requirements as high as 15 to 20g have been recommended for men working under hot conditions with profuse sweating (7,21,22). A recent review by Hubbard et al. (12) stated that lack of agreement between these earlier studies probably is due to uncontrolled fluid replacement, exercise level, heat acclimation (HA), and dietary-salt stabilization.