**Abstract**

Flaxseed (*Linum usitatissimum* L.), one of the oldest cultivated crops, continues to be widely grown for oil, fiber, and food. This herb is used in the food culture of some countries with different purposes. Flaxseed is one of the richest plants in terms of some nutrients. Numerous studies have shown that in terms of omega-3 fatty acids, this herb is one of the richest sources in the diet. Also, the lignan content in flaxseed is significantly higher than that in other plants. Also, the lignan content in flaxseed is significantly higher than that in other plants. In this chapter, the structure and chemical properties of this plant have been investigated first, and then the effectiveness of flaxseed in some chronic diseases has been mentioned.

**Keywords:** flaxseed, Lignan, omega-3, obesity, antioxidant, chemical composition
