Roasted Barley Extract (Mugi-cha) Containing Cyclo(d‑Phe‑l‑Pro) Prevents Lowering of the Cutaneous Blood Flow and Skin Temperature under Air Conditioning: A Randomized, Double-Blind, Placebo-Controlled, Crossover Study

• Published in: Journal of agricultural and food chemistry Vol. 66; no. 23; pp. 5901 - 5906
• Main Authors: Ashigai, Hiroshi, Mizutani, Mai, Taniguchi, Yoshimasa, Matsukura, Yasuko, Nakashima, Keiko, Ikeshima, Emiko, Yajima, Hiroaki
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 13.06.2018
• Subjects: Adult; Air Conditioning; analysis of variance; barley; beverages; blood flow; Blood Flow Velocity - drug effects; Cross-Over Studies; Dipeptides - analysis; Dipeptides - pharmacology; Double-Blind Method; Female; Food Handling - methods; Hordeum - chemistry; Hot Temperature; Humans; Male; Peptides, Cyclic - analysis; Peptides, Cyclic - pharmacology; Placebos; Plant Extracts - chemistry; Plant Extracts - pharmacology; sensation; Skin - blood supply; skin temperature; Skin Temperature - drug effects; water; cutaneous blood flow; roasted barley extract; cyclo(d-Phe-l-Pro); skin temperature; air conditioning
• ISSN: 0021-8561; 1520-5118; 1520-5118
• DOI: 10.1021/acs.jafc.8b02485

Roasted barley extract (RBE), also known as mugi-cha, is a well-known healthy non-caffeinated beverage, and its health functionality has been widely reported. Our previous clinical study showed that RBE affects the cutaneous blood flow and skin temperature after cold-water immersion and that cyclo­(d-Phe-l-Pro) is responsible for its effect. In this study, we investigated whether cyclo­(d-Phe-l-Pro)-containing RBE prevents the decrease in the cutaneous blood flow and skin temperature. Subjects remained in the air-conditioned room while ingesting RBE or a placebo. We measured the cutaneous blood flow and skin temperature. We evaluated the effect of RBE administration by two-way repeated measures analysis of variance. A total of 15 subjects were enrolled. The change in cutaneous blood flow in the RBE and placebo groups was −0.79 ± 0.38 and −2.03 ± 0.35 mL min–1 100 g–1, respectively (p value of 0.041). The change in the skin temperature in the RBE and placebo groups was −1.85 ± 0.35 and −3.02 ± 0.30 °C, respectively (p value of <0.001). We also did subclass analysis with cold-feeling subjects. For the seven subjects who had cold sensation, the change in the cutaneous blood flow in the RBE and placebo groups was −0.48 ± 0.58 and −2.56 ± 0.48 mL min–1 100 g–1, respectively (p value of 0.008). The change in the skin temperature in the RBE and placebo groups was −1.46 ± 0.74 and −2.89 ± 0.39 °C, respectively (p value of 0.009). Thus, RBE containing cyclo­(d-Phe-l-Pro) prevents the decrease in the cutaneous blood flow and skin temperature under air conditioning.