Importance of interaction between the matrix effect and microbial metabolism in the bioavailability of lignans

Background: Plant-lignans are polyphenols with low bioavailability and bioactivity that are transformed by the intestinal microbiota into enterolignans. Our hypotheses are: (i) the way in which plant-lignans are ingested in the diet affects, in a decisive way, the microbial metabolism of these compounds and (ii) an increase in lignan bioaccessibility will produce an increase in enterolignans produced by the intestinal microbiota, increasing the bioavailability of lignans ingested in the diet. Therefore, our aims were to determine how the matrix effect affects the metabolism of lignans by the intestinal microbiota and how improving the bioaccessibility of lignans ingested in the diet improves their bioavailability.  Results: Human faecal samples showed close to 50 times higher efficiency in the production of enterolactone (ENL) from secoisolariciresinol than from flaxseed extracts. ENL is the main enterolignan produced by the intestinal microbiota, and it is mainly produced from dihydroxy-ENL (DHENL) via hydroxy-ENL (HENL). Moreover, the human faecal samples were able to hydrogenate and hydroxylate the ENL. On the other hand, the fermentation of a lignan-enriched food by Bifidobacterium pseudocatenulatum INIA P815 increased the concentration of lignans in the plasma and liver of mice that consumed a diet rich in lignans. DHENL, HENL and ENL showed the highest bioavailability.  Conclusion: The matrix effect is a determining factor in the bioaccessibility and the efficiency of transformation of lignans into enterolignans by the intestinal microbiota. The reduction of the matrix effect increases the production of enterolignans (DHENL, HENL and ENL) by the intestinal microbiota, increasing the bioavailability of ingested lignans. © 2025 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.