Intake of whole grains and vegetables determines the plasma enterolactone concentration of Danish women.

The mammalian lignan enterolactone (ENL), which is produced from dietary plant-lignan precursors by the intestinal microflora, may protect against breast cancer and other hormone-dependent cancers. This cross-sectional study examined which variables related to diet and lifestyle were associated with high plasma concentrations of ENL in Danish postmenopausal women. Plasma ENL was measured by time-resolved fluoroimmunoassay in 857 Danish women aged 50-64 y who participated in a prospective cohort study. Diet was assessed using a semiquantitative FFQ, and background information on lifestyle was collected using a self-administered questionnaire. Multiple analyses of covariance were completed in two steps. The median plasma ENL concentration was 27 nmol/L (range 0-455 nmol/L). In covariance analyses, positive associations were found between consumption of cereals, vegetables, and beverages and plasma ENL concentration. When analyzing subgroups of these food groups, the associations were confined to whole-grain products, cabbage, leafy vegetables, and coffee. For fat and the nondietary variables, negative associations between BMI, smoking, and frequency of bowel movements and plasma ENL concentration were observed. These data show that foods high in ENL precursors are associated with high concentrations of ENL. Furthermore, smoking, frequent bowel movements, and consumption of fat seems to have a negative affect on the ENL concentration. In conclusion, whole grains and vegetables are the most important dietary providers of plant lignans for the concentration of ENL in Danish postmenopausal women, and if ENL is found to protect against cancer or heart disease, the intake of whole grains and vegetables should be increased.