Assessment of Data on the Lignan Content of Foods

The plant lignans, secoisolariciresinol (SEC) and matairesinol (MAT) are converted to the metabolites, enterodiol (ED) and enterolactone (EL), known as the mammalian lignans in the gastrointestinal tract. In vitro, mammalian lignans may have both estrogenic and antiestrogenic properties. Increased consumption of lignan-rich foods through the addition of brans, oilseeds and cereals in bread, muffins, health bars and breakfast cereal or emphasis on fruits and vegetables in a balanced diet has lead to the need for reliable data on lignan content in foods. The quantitative determination of the lignans to date by a direct method has involved hydrolysis of the glycoside and analysis of the resulting aglycones (SEC and MAT). The in vitro fermentation methodology, which simulates colonic fermentation with fecal microflora, has been utilized in the indirect analysis of foods where ED and EL are measured as an indication of the plant lignans. A compilation of the available data on the lignan content of various food groups and the assessment of these data by contrasting two different analytical methodologies are given. In general, in vitro fermentation gave higher values, compared to direct analysis, for most foods for which comparisons could be made.