Lignans are naturally occurring chemicals widespread within the plant and animal kingdoms. Several lignans—with intimidating names such as secoisolariciresinol—are considered to be phytoestrogens, plant chemicals that mimic the hormone estrogen. These are especially abundant in flaxseeds and sesame seeds. Bacteria in our intestines convert the naturally occurring phytoestrogens from flaxseed into two other lignans, enterolactone and enterodiol, which also have estrogen-like effects. In this article, the term lignans refers to these two specific lignans as well as the phytoestrogen kind, but not to the wide variety of other lignans.
Effective dosages of purified lignans have not been determined. In studies of flaxseed as a source of lignans, flaxseed has been taken at a dose of 5 to 38 g daily.
Cooking flaxseed apparently does not decrease the amount of lignans absorbed by the body.
What Is the Scientific Evidence for Lignans?
This, however, does not prove that lignans are the cause of the benefit, for other factors in these foods, or in the characteristics of the people who consume these foods, may have been responsible. Double-blind, placebo-controlled studies are necessary to prove that a medical treatment provides benefits, and none have yet been reported for lignans. (For information on why this type of study is so important, see Why Does This Database Rely on Double-blind Studies? )
Other potential concerns are discussed in the safety section of the Flaxseed article.
- Reviewer: EBSCO CAM Review Board
- Review Date: 08/2013 -
- Update Date: 08/22/2013 -