Comparison of plasma alkylresorcinols (AR) and urinary AR metabolites as biomarkers of compliance in a short-term, whole-grain intervention study

Authors: MCKEOWN, NICOLA - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; MARKLUND, MATTI - Uppsala University; MA, JIANTAO - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; ROSS, ALASTAIR - Chalmers University Of Technology; LICHTENSTEIN, ALICE - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; LIVINGSTON, KARA - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; JACQUES, PAUL - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; RASMUSSEN, HELEN - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; BLUMBERG, JEFFREY - Jean Mayer Human Nutrition Research Center On Aging At Tufts University; CHEN, CHUNG-YEN - Jean Mayer Human Nutrition Research Center On Aging At Tufts University

Submitted to: European Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/20/2015
Publication Date: 6/5/2015
Citation: McKeown, N.M., Marklund, M., Ma, J., Ross, A.B., Lichtenstein, A.H., Livingston, K.A., Jacques, P.F., Rasmussen, H.B., Blumberg, J.B., Chen, C. 2015. Comparison of plasma alkylresorcinols (AR) and urinary AR metabolites as biomarkers of compliance in a short-term, whole-grain intervention study. European Journal of Clinical Nutrition. 55(3):1235-1244. https://doi.org/10.1007/s00394-015-0936-8.
DOI: https://doi.org/10.1007/s00394-015-0936-8

Interpretive Summary: Several epidemiological studies have linked higher whole grain intake with improved cardiometabolic risk factors and reduced risk of chronic disease using a variety of dietary assessment methods to record intake. However, there are many factors that may bias self reports of whole grain intake in observational and intervention studies and confound research examining the health effects of whole grains. As such, there is a need for reliable, independent biochemical markers of whole grain intake in research studies. In this study, we examined plasma alkylresorcinols, a class of lipids present in wheat and rye bran, as well as urinary metabolites of alkylresorcinols to see if either would be suitable biomarkers of whole grain wheat or rye consumption. In a randomized crossover study, urinary total alkylresorcinol metabolites and plasma total alkylresorcinols were assessed in 19 subjects after they consumed either 3 or 6 servings of whole grains daily for 1 week. Urinary total alkylresorcinol metabolites were significantly higher after 6 compared to 3 servings of whole grains. Plasma total alkylresorcinols tended to be higher after 6 compared to 3 servings of whole grains, but the difference was not statistically significant. Thus, urinary alkylresorcinol metabolites from 24-hour urine collections may be useful as biomarkers of whole grain consumption.

Technical Abstract: PURPOSE: Alkylresorcinols (AR) are phenolic lipids present in the bran of wheat and rye. Plasma AR and their urinary metabolites may be suitable biomarkers of whole-grain (WG) wheat and rye consumption. The objective of this study was to examine plasma AR and urinary AR metabolites in response to WG wheat consumption. METHODS: In a randomized crossover study, 19 subjects (10 males, 9 females; BMI 22.0 kg/m^2; age 26 years) incorporated either 3 servings (48 g) or 6 servings (96 g) of WG wheat daily into their regular diet for 1 week. Subjects completed a 2-week washout period, abstaining from all WG consumption, before each intervention. Fasting blood and 24-h urine were collected before and after each intervention. Plasma AR homologues (C19:0, C21:0, C23:0) were quantified by GC-MS after diethyl ether and solid phase extraction and derivatization. Urinary AR metabolites [3,5-dihydroxybenzoic acid and 3-(3,5-dihydroxyphenyl)-propanoic acid] were determined using HPLC with electrochemical detection after enzymatic deconjugation and ethyl acetate extraction. RESULTS: Urinary total AR metabolites were significantly higher after 6 compared with 3 servings of WG wheat (56 vs. 32 micromol/day, P < 0.001). This dose-response relationship was independent of age, sex, energy intake, and baseline urinary AR metabolite concentration. Plasma total AR tended to be higher after 6 compared with 3 servings of WG wheat (103.0 vs. 86.9 nmol/L), but this difference was not significant (P = 0.42). CONCLUSION: The results suggest that urinary AR metabolites from 24-h urine collections may be useful as biomarkers of compliance in intervention studies of WG wheat.