Effect of ascorbic acid on rate of heat acclimatization

There is some indication in the literature that ascorbic acid (vitamin C) may reduce the physiological responses to heat stress. Consequently, the effect of ascorbic acid ingestion on heat-strain indicators has been studied on a group of 60 mining recruits undergoing climatic room acclimatization. Of the 60 men, 19 received a daily dose of 250 mg ascorbic acid; 21 a daily dose of 500 mg ascorbic acid; and 20 received a placebo daily. Measurements of rectal temperature, heart rate, and hourly sweat rate were made on all subjects during the 4 h of heat exposure per day for 10 days. The wet bulb temperature was 32.2 degrees C, the dry bulb 33.9 degrees C, the air movement 0.4 m/s, and the work rate 35 W. The results indicate that the rate and degree of acclimatization, as assessed by 4th-h rectal temperature, is enhanced by ascorbic acid supplementation and that no differences in response could be shown between daily dosages of 250 and 500 mg of vitamin C.