Plasma and adipose tissue alkylresorcinols in women and men as biomarkers of whole grain wheat and rye intake

Abstract: Epidemiological studies have demonstrated several health benefits associated with whole grain intake, including prevention of cardiovascular disease, type II diabetes, colorectal cancer, obesity and mortality. Whole grain products are therefore recommended by national agencies. However, a nationwide investigation performed in 2010 revealed that the Swedish population only consumed about half of the recommended daily intake. There are various challenges associated with the estimation of whole grain intake. Common methods used for measuring consumption may differ in how comprehensive and detailed the provided information is, which may affect accuracy. Participants may also influence accuracy due to limited memory capacity, which is central in some methods. Moreover, different definitions of whole grain and whole grain products has been used in different studies. Alkylresorcinols (AR), is a group of phenolic lipids that has been suggested as biomarkers of whole grain wheat and rye intake. AR may therefore serve as an objective tool to estimate whole grain intake and to avoid problems inherent to self-reported intake. Alkylresorcinols are derivates of 1,3-dihydroxybenzene and are only found in the outer layers of wheat, rye and barley and can therefore mirror the intake of whole grain products made from these cereals. AR in plasma has been evaluated and used as biomarkers in several studies but the relative short half-life, limits their use to populations with a stable and frequent intake. Moreover, some studies have suggested differences in AR concentrations between men and women. Recently, AR were found in adipose tissue samples from humans and the adipose tissue concentrations were correlated with whole grain product intake in a pilot study. The aim of this study was to quantify alkylresorcinols in human plasma and to compare the concentration between women and men. The aim was further to correlate AR concentrations in adipose tissue, with the concentrations in plasma of Swedish women and men. The result showed no significant difference of plasma alkylresorcinols between women and men (P=0.142-0.966) which contradicted to other studies in which men had higher values. However, the adipose tissue alkylresorcinols showed a significant difference between men and women (P=0.003-0.047). A strong correlation between the plasma alkylresorcinols and adipose tissue alkylresorcinols was observed (r=0,466-0,823, P=<0.0001). The correlation for the shortest alkylresorcinol homologue (C17:0) was significantly strongest for both men, women and the sexes together (r=0.801- 0.823, p<0.0001).