Lignans are a group of phytoestrogens found in plants with a structure similar to estrogen. They are present in high concentrations in seeds, whole grains, and vegetables. Flaxseeds are notably one of the richest sources of lignans, especially lignan secoisolariciresinol diglucoside (SDG). When consumed, lignans are metabolized by gut bacteria into enterolignans, which can have various beneficial health effects. These include possible roles in risk reduction of certain cancers (like breast and prostate cancer), providing cardiovascular benefits by improving lipid profiles and blood pressure and possessing antioxidant properties that help combat oxidative stress. Lignans also show promise in modulating the immune response and have been researched for their potential in treating menopausal symptoms due to their estrogenic activity. However, the health impacts of lignans can vary widely among individuals, largely due to differences in gut microbiota composition, which affects their metabolism and bioavailability.