lignanen

Lignans, or lignanen in some languages, are a class of plant secondary metabolites belonging to the polyphenols. They are derived from the phenylpropanoid pathway and are characterized by a dibenzylbutane skeleton formed by the coupling of two cinnamyl alcohol units.

Lignans occur in a variety of plants, with flaxseed (linseed) containing the highest amounts of SDG (secoisolariciresinol diglucoside), a major plant lignan. Other dietary sources include sesame seeds, whole grains such as rye and oats, legumes, and some fruits and vegetables. In plants, lignans are believed to serve roles in defense and structural function.

In humans, lignans are largely considered phytoestrogens because gut microbiota convert plant lignans into enterolignans, mainly enterodiol and enterolactone. The bioactivity of these metabolites is weaker than that of endogenous estrogens, but they may interact with estrogen receptors and influence hormone-related processes. The extent of metabolism and circulating levels depends on gut microbiota composition and overall diet.

Health effects of lignans are studied mainly through observational studies and smaller trials. Some data suggest associations with reduced risk of certain hormone-related cancers and cardiovascular disease, but results are inconsistent and mechanisms are not fully established. Lignans also show antioxidant and anti-inflammatory activities in laboratory settings, though clinically relevant effects remain uncertain.

Lignans are distinct from lignin, the plant cell-wall polymer. They are used as dietary components and are of interest in functional foods and nutraceuticals, particularly those emphasizing flaxseed and other high-lignan foods.