Relation between plasma enterodiol and enterolactone and dietary intake of lignans in a Dutch endoscopy-based population

Enterolignans are phytoestrogenic compounds derived from the conversion of dietary lignans by the intestinal microflora that may be protective against cardiovascular diseases and cancer. To evaluate the use of enterolignans as biomarkers of dietary lignan intake, we studied the relation between plasma and dietary lignans. We determined the dietary intake of 4 lignans (secoisolariciresinol (SECO), matairesinol (MAT), pinoresinol, and lariciresinol) using the European Prospective Investigation into Cancer and Nutrition FFQ, and plasma enterodiol (END) and enterolactone (ENL) concentrations were determined by liquid chromatography-tandem mass spectrometry. The population consisted of 637 men and women, aged 19-75 y, participating in a case-control study on colorectal adenomas. Participants did not use antibiotics in the preceding calendar year. We found a modest association between lignan intake and plasma END (Spearman r = 0.09, P = 0.03) and ENL (Spearman r = 0.18, P < 0.001). The correlation of total lignan intake with plasma enterolignans was slightly stronger than that of only SECO plus MAT. The plasma concentrations of both END and ENL were associated with intake of dietary fiber and vegetable protein but not with intake of other macronutrients. The relation between lignan intake and plasma END was modulated by age and previous use of antibiotics, whereas for ENL, it was modulated by weight, current smoking, and frequency of defecation. However, even when we included these nondietary factors in the regression models, the explained variance in plasma END and ENL remained low (2 and 13%, respectively).