The flax plant (Linum usitatissimum) is an annual herb. The seeds are also one of the
richest dietary sources of phytoestrogens (estrogenic compounds derived from plants). Because
flaxseed is the richest dietary source of lignans, it has been used to investigate the potentially
anticarcinogenic effects of lignans in animal studies and some human trials. The plant lignan
secoisolariciresinol diglycoside (SDG) has been suggested to be the primary effector of the
antitumorigenic effects of flaxseed observed in vitro with mammary and colon carcinogenesis
models. Proposed mechanisms to date for the observed inhibition of tumor growth have
included estrogenic and antiestrogenic effects, anti-oxidative effects, antiproliferative and antiaromatase
effects. This review addresses some of the animal and human studies of flaxseed’s
anticarcinogenic effects in breast, melanoma, and prostate cancers. The data on possible
antitumorigenic effects of flaxseed in humans are inconclusive at best, however, in vitro data
suggest that SDG as an anticarcinogenic agent warrants further study. Its potential mechanism
of action in cancer prevention remains unclear. Flaxseed supplementation for its own sake is
harmless, however, and potentially beneficial in other ways not addressed by this review.
Flaxseed
The flax plant (Linum usitatissimum) is an annual herb believed to have originated in
Egypt. The plant’s fibers are used to make linen cloth, and its oil, also known as linseed
oil, has many industrial uses. The seeds are also one of the richest dietary sources of
phytoestrogens, estrogenic compounds derived from plants. Phytoestrogens are divided
into three main classes, isoflavonones, coumestans, and lignans. Isoflavones are found
predominantly in legumes, such as soybeans. Coumestrol is found mainly in alfalfa and
clovers. Lignans are the most ubiquitous phytoestrogens because they are involved in
plant cell wall formation. Plant lignans can be converted to the mammalian lignans,
enterolactone and enterodio |
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