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).