Plasma alkylresorcinols as a biomarker of whole-grain food consumption in a large population: results from the WHOLEheart Intervention Study

Abstract

Background: Small-scale, short-term intervention studies have suggested that plasma alkylresorcinol (AR) concentrations may be biomarkers of whole grain (WG) wheat and rye intakes. Objective: The objective was to determine whether plasma AR concentrations reflect self-reported WG food intake in a 16-wk WG intervention study and to establish which phenotypic characteristics influence plasma AR concentrations. Design: In a randomized parallel-group dietary intervention study, 316 overweight and obese participants with a WG intake of ,30 g/d were recruited and randomly assigned to 1 of 3 groups: control (no dietary change), intervention 1 (60 g WG/d for 16 wk), or intervention 2 (60 g WG/d for 8 wk followed by 120 g WG/d for 8 wk). Fasting blood samples were collected at baseline, 8 wk, and 16 wk for the measurement of plasma lipids and ARs. Results: Plasma samples from 266 study completers were analyzed. Total plasma AR concentrations increased with the WG intervention and could be used to distinguish between control subjects and those who consumed 60 or 120 g WG, but not between those who consumed 60 and 120 g WG. Plasma AR concentrations were higher in men, were positively associated with plasma triglyceride concentrations, and were negatively associated with nonesterified fatty acids. Conclusions: Plasma AR concentrations were correlated with WG intake and could be used to distinguish between low-and high-WG consumers. Sex and plasma lipid concentrations independently influenced plasma AR concentrations, although plasma triglycerides may explain higher concentrations in men. This trial is registered as ISRCT no. 83078872.Am J Clin Nutr 2012;95:204-11.

Plasma Alkylresorcinols, Biomarkers of Whole-Grain Intake, Are Related to Lower BMI in Older Adults

“…In a large cohort of overweight participants undergoing a whole-grain-based intervention in the United Kingdom, the correlation between plasma AR and estimates of whole-grain intake derived from a general diet FFQ was 0.36. This correlation increased to 0.45 for plasma AR and whole-grain wheat intake after adjustment for sex, study center, and plasma lipid concentration (7). Observed correlations between whole-grain intake and plasma AR were lower in the present study, possibly due to the narrow and low range of intake; most participants consumed <1 daily serving (16 g) of whole grains.…”

“…The discrepancy from previous studies may be due to the fact that all female participants had been postmenopausal for $5 y. In those studies in which sex was found to be a significant determinant of plasma AR (7,13), female participants were largely premenopausal. As in several previous studies (5,7), adjustment for fasting TG did not alter the correlation coefficients, suggesting that although AR are transported in lipoproteins (26), this is not an important determinant of fasting plasma AR concentration.…”

“…First, its cross-sectional nature limits our ability to infer causality between biomarkers of dietary exposures and BMI. Second, only a single measure of plasma AR was available in this study and, thus, we were unable to examine the long-term reproducibility of plasma AR, although past studies have found repeated measures in free-living participants to be reproducible (7,12,13). Third, the percentage of trunk fat reflects the percentage of adipose tissue in the whole trunk region and this may not represent true intraabdominal adipose tissue, particularly in women.…”

“…Recent intervention studies have shown that plasma concentrations of alkylresorcinols (AR; 1, 3-dihydroxy-5-alkylbenzene homologs) and their metabolites are biomarkers of whole-grain wheat and rye intake (5)(6)(7). AR are found primarily in the bran fraction of certain whole grains (wheat, rye, and barley) (8), and once consumed, they are rapidly absorbed (9) and metabolized (10).…”

“…It is estimated that the half-life of plasma AR is ;5 h (11), and thus plasma concentrations reflect the short-term intake of certain whole-grain foods. Intervention studies have shown that plasma AR is responsive to whole-grain wheat and rye intake (5,7), and recent evidence suggests that plasma AR concentration is moderately reproducible over 3-4-mo periods (7,12,13). Because major sources of AR, such as ready-to-eat cereal and whole-grain wheat bread, are usually consumed on a daily basis, plasma AR may be a useful marker of habitual consumption in populations with a stable intake of whole-grain foods.…”