Flaxseed is the seed of the Linum usitatissimum plant, which has been used for textile production (linen) and as animal feed for many years. More recently, flaxseed has been noted to have several health benefits in humans and has become more common in human diets and as a supplement.
Flaxseed is high in fiber, with about 28% of its mass being fiber, a third of which is soluble fiber. It also contains around 30% protein, 22% alpha-linolenic acid (ALA), and phenolic compounds, including a type of phytoestrogen called lignan.[1][2]