We examined the effect of intake of a catechin-enriched ion beverage (Cat-I) on the thermoregulatory response in a hot environment. Eight healthy men were exposed to a hot environment for 90 min at an ambient temperature of 35 °C (relative humidity: 75%) combined with lower leg water immersion at 40 °C. At that time, either Cat-I, an ion beverage (Ion), or mineral water (Placebo) was consumed at three points: (1) at the start of lower leg immersion, (2) at 30 min after immersion, and (3) at 60 min after immersion. In all conditions, tympanic temperature (Tty) increased gradually during lower leg water immersion. However, the rate of increase of Tty tended to be suppressed after 30 min. The effect of drinking Cat-I had a limited detection period of approximately 60-70 min, and the rate of sweating was clearly increased with Cat-I compared with Ion and Placebo. Cat-I also tended to decrease the body temperature threshold at which sweating was induced compared with Ion or Placebo. These findings suggest that Cat-I efficiently suppressed the increase of body temperature in a hot environment.
Keywords: Catechin-enriched ion beverage; Hypotonic beverage; Skin blood flow; Sweat rate; Thermoregulatory function.