Fig. 2

Representative four plasma metabolite markers identified in the priests. Dots represent subjects (circle, priests; square, controls), and line represents median. a Methionine in plasma of priests vs. the controls (P = 0.0002, r = − 0.761). b 3-Aminoisobutyric acid (BAIBA) in plasma of priests vs. the controls (P = 0.0015, r = − 0.676). c Phenylalanine in plasma of priests vs. the controls (P = 0.0029, r = − 0.642). d Choline in plasma of priests vs. the controls (P = 0.0052, r = − 0.608). Plasma level of each metabolite was shown as the relative area value calculated for metabolomics analysis by the Human Metabolome Technologies, Inc. The relative area value was defined as the relative concentration of each metabolite. Differences of each plasma metabolites were compared using a Mann–Whitney U test, indicating P value and the effect size r. Statistical significance was defined as P < 0.05. Cohen’s guidelines for the effect sizes (r) for Mann–Whitney U test are that a large effect is 0.5, a medium effect is 0.3, and small effect is 0.1 [28]