Roasted Barley Extract (Mugicha) Containing Cyclo(D-Phe-L-Pro) Prevents a Decrease in Skin Temperature in Cold...

Area of Science:

• Human Physiology
• Nutritional Science
• Thermophysiology

Background:

• Roasted barley extract (RBE) is a traditional Japanese beverage with potential physiological effects.
• Previous research indicated RBE containing cyclo(d-Phe-l-Pro) influences blood flow and skin temperature recovery in women.
• The efficacy of RBE on skin temperature regulation in men was previously unclear.

Purpose of the Study:

• To investigate the effects of RBE containing cyclo(d-Phe-l-Pro) on skin temperature in men and women under controlled cold air exposure.
• To determine if RBE can prevent decreases in skin temperature in excessively air-cooled environments.

Main Methods:

• A randomized, double-blind, placebo-controlled study was conducted.
• Participants ingested either RBE or a placebo beverage and remained in a cooled room (25.5±0.5ºC) for 100 minutes.
• Infrared thermography was used to measure left foot skin temperature every 5 minutes; paired t-tests analyzed the data.

Main Results:

• The RBE group maintained significantly higher skin temperatures compared to the placebo group.
• Overall, skin temperature changes after 100 minutes were -3.67±1.14ºC for RBE versus -4.59±0.89ºC for placebo.
• RBE demonstrated efficacy in both male and female participants, with skin temperature changes of -3.65±0.64ºC (RBE) and -4.55±0.32ºC (placebo) in men.

Conclusions:

• Roasted barley extract containing cyclo(d-Phe-l-Pro) effectively prevents skin temperature decrease in excessively air-cooled conditions.
• The thermoregulatory benefits of RBE were confirmed in both male and female participants.
• RBE represents a potential dietary intervention for maintaining body temperature in cold environments.