Determinants of serum enterolactone concentration.

BACKGROUND: The lignan enterolactone, which is produced by the intestinal microflora from dietary precursors, may protect against hormone-dependent cancers and cardiovascular diseases.
OBJECTIVE: We examined the cross-sectional associations between the serum enterolactone concentration and variables related to diet and health in Finnish adults.
DESIGN: Serum enterolactone was measured by using time-resolved fluoroimmunoassay in 2380 Finnish men and women aged 25-64 y who were participating in a cross-sectional national survey in 1997. Background information was collected with self-administered questionnaires and the diet was assessed with a food-frequency questionnaire.
RESULTS: The median serum enterolactone concentration was 13.8 nmol/L (range: 0-95.6 nmol/L) in men and 16.6 nmol/L (range: 0-182.6 nmol/L) in women. Multiple regression analyses showed positive associations in men between the serum enterolactone concentration and constipation, consumption of whole-grain products, and intake of fruit and berries. In women, the serum enterolactone concentration was positively and independently associated with consumption of vegetables, subject age, and constipation and was negatively associated with smoking. Furthermore, female subjects of normal weight had significantly higher serum enterolactone concentrations than did their underweight or obese peers.
CONCLUSIONS: The serum enterolactone concentration varies widely in the population. Of the variables we examined, the most important determinants of the serum enterolactone concentration were consumption of lignan-containing foods and constipation; however, these appeared to explain only a small part of the variation. Therefore, the role of gut microflora in the metabolism of lignans might be very important. Further studies will also be needed to determine the bioavailability and absorption rate of lignans.