Urinary 3-(3,5-Dihydroxyphenyl)-1-Propanoic Acid, an Alkylresorcinol Metabolite, Is a Potential Biomarker of Whole-Grain

n-Alkylresorcinols (AR) are a major group of phenolic compounds in whole-grain wheat, rye, and barley. As such, they may serve as potential biomarkers of whole-grain intake, because they are quantifiable intact in plasma and as metabolites in urine. We examined relationships between 12-h urinary excretion of AR metabolite 3-(3,5-dihydroxyphenyl)-1-propanoic acid (DHPPA) and self-reported habitual intake of whole-grain foods measured by 3-d food record (3DFR) and FFQ. Urine samples from 100 men and women were analyzed for DHPPA using HPLC with coularray detection. DHPPA excretion ranged from 1.3 to 99.4 (mean 6 SE, 14.0 6 1.5) mmol/12 h. Whole-grain food intake, as determined by 3DFR and FFQ and adjusted for BMI and energy and fiber intake, was significantly associated with 12-h urinary DHPPA excretion. Based on 3DFR, whole-grain wheat 1 rye consumers had a 44% higher DHPPA excretion than nonconsumers (ratio of excretion (95% CI) ¼ 1.44 (1.04, 1.97); P ¼ 0.029). Using whole-grain intake estimated by FFQ, a serving increase in whole-grain wheat 1 rye intake increased DHPPA excretion by 94% (ratio of excretion (95% CI) ¼ 1.94 (1.35, 2.78); P ¼ 0.001) and a serving increase in whole grains as defined more broadly in epidemiologic studies of whole-grain intake and disease risk (whole-grain wheat, rye, oats, and corn) increased DHPPA by 67% (ratio of excretion (95% CI) ¼ 1.67 (1.28, 2.17); P , 0.0001). This study supports the potential utility of urinary DHPPA as a biomarker of whole-grain intake in a U.S. population. J. Nutr. 138: 1957-1962, 2008.