Requirements of sodium chloride during summer in the tropics

¹ Defence Science Laboratory, Ministry of Defence, New Delhi, India

Data are presented on salt requirements in the tropics, based on observations on 24 acclimatized Indian subjects given diets containing 16.2, 11.2, 8.7, 6.2 and 3.1 gm of salt per day. Adequacy of salt diet was tested from the chloride excretion in urine and from the changes observed in thiocyanate space and plasma chloride concentration at the start and after the subjects had been on the restricted salt diet for a week. Sweat and chloride losses at different environmental temperatures were studied. The salt requirement of subjects walking for 2 hours in the sun at a speed of about 3.5 mph was found to be about 6.2 gm/day when the mean maximum environmental temperature was 100.7°F D.B. The requirement was found to increase by 0.063 gm/°F rise in D.B. temperature for 2 hours' exercise.