Intake of lignans is associated with serum enterolactone concentration in Finnish men and women.

The mammalian lignans (a form of phytoestrogens), metabolically derived by the intestinal microflora from dietary precursors, may have several health benefits. Information concerning their dietary sources and bioavailability is scarce. We assessed lignan intake via a 24-h dietary recall (n = 2852) and determined serum enterolactone (EL) concentration (n = 1784) in 25- to 64-y-old Finnish men and women participating in a national survey in 1997. Mean intake of lignans [sum of matairesinol (MAT) and secoisolariciresinol (SECO)] in men and women was 173 microg/d (19 microg/MJ) and 151 microg/d (23 microg/MJ), respectively. SECO made up over two thirds of the total lignan intake. The major sources of SECO were fruit, berries and cereals, whereas MAT derived almost exclusively from cereals. Lignan intake was positively associated with serum EL concentration (r = 0.19, P < 0.0001), i.e., the mean EL concentration in the highest quintile of lignan intake was 50% higher than that in the lowest quintile. We conclude that lignans are common components of the Finnish diet, although the mean daily intake is low (<0.2 mg). The main dietary sources of lignans, i.e., whole grain, vegetables and fruits, are foods commonly associated with lower risk of cardiovascular diseases and cancer. Serum EL concentration is a feasible biomarker of lignan intake.