KEYWORDS:lignans, phytoestrogens, secoisolariciresinol, liquid chromatography, mass spectrometry, food composition, intake, cancer, cardiovascular diseases, mortalityPlant lignans are diphenolic compounds that are present in many plant foods. The plant lignans lariciresinol (LARI), pinoresinol (PINO), secoisolariciresinol (SECO), and matairesinol (MAT) are efficiently converted into enterolignans by the intestinal microflora. Enterolignans possess several biological activities, e.g. antioxidant and estrogen-like activities by which they may reduce the risk of chronic diseases. Studies on the health effects of lignans were hampered by the lack of comprehensive data on the lignan contents of foods and diets.Therefore, we developed a liquid chromatography-tandem mass spectrometry method to measure these four lignans in foods and beverages; and we constructed a lignan database with lignan contents of 83 solid foods and 26 beverages commonly consumed in theNetherlands. Almost all plant foods contained lignans. The most abundant lignan sources were flaxseed (≈ 300 mg/100 g; mainly SECO); and sesame seeds (≈ 40 mg/100 g; mainly PINO). The lignan contents of grain products, vegetables, fruits and legumes varied mostly between 50 and 200 µg/100 g.Highervalues were found for Brassica vegetables, garlic, French beans, apricots, strawberries, and peaches. Lignan contents in beverages ranged from 0 for cola to 91 µg/100 ml for red wine.The median total lignan intake among a representative sample of Dutch adults was979 µg/d (range 43-77584 µg/d). LARI plus PINO contributed 75% to the lignan intake, whereas SECO plus MAT only 25%. Remarkably, the major food sources of lignans were beverages (37%), followed by vegetables (24%), nuts and seeds (14%), bread (9%) and fruits (7%).Besides the consumption of lignan-rich foods, the major determinants of plasma enterolignan concentrations in an endoscopy-based population of 637 adults were defecation frequency, smoking, and body weight. The correlation between total lignan intake and ...