Flaxseed, Lignans and Cancer. Flaxseed in Human Nutrition.
Flaxseed, Lignans and Cancer. Flaxseed in Human Nutrition.
Year: 1995
Authors: L U Thompson.
Publication Name: AOCS Press, Champaign, Ill.
Publication Details: 221;235.
Abstract:
Previous research by the author reported that the lignan content of flaxseed is 75-800 times that of 66 other plant foods. In this chapter, Thompson provides an overview of animal studies that have identified the anticarcinogenic properties of flaxseed lignans. She notes that several observations have lead to the hypothesis that lignans have anticancer properties. In breast cancer patients and individuals at high risk of breast and colon cancer, the urinary excretion of mammalian lignans is significantly lower than in individuals who consume vegetarian diets or those at lower risk of developing cancer. Lignan structure is very similar to anti-carcinogenic compounds such as tamoxifen which has weak estrogenic/anti-estrogenic properties. Some lignans have been found to have antimitotic, anti-estrogenic, antiviral, antibacterial and anti-fungal properties. A number of studies in animal models have shown a protective effect of flaxseed lignans on both mammary and colon carcinogenesis. Flaxseed lignans have been shown to significantly inhibit cancer development at both the promotional and initiation stages of the disease through mechanisms that inhibited growth and proliferation of cancer cells. Flaxseed supplementation has been shown to lower early neoplastic indices in the colon and mammary glands of animals. Significant reductions in mammary tumor size and number have been found following flaxseed feeding. Flaxseed and SDG have been shown to decrease colon cancer risk markers such as the size and multiplicity of aberrant crypt foci in carcinogenic treated rats. Nuclear aberrations are also decreased following flaxseed feeding. Research by the author has suggested that the lowering of cell proliferation rates by flaxseed may yield the nucleus of cells less susceptible to carcinogenic damage. Significant negative relationships between urinary lignan excretion and nuclear aberrations have also been reported. Purified SDG produces similar effects to flaxseed or flaxseed meal, suggesting that SDG may be the active component in flaxseed. SDG may act by inhibiting the binding of estrogen to its receptors and block estrogen-induced hypertrophy. Mammalian lignans have been found to inhibit aromatase, an enzyme involved in the production of estrone from androgens, thus reducing the tumor’s source of endogenous estrogens. The author concludes that studies with several animal models have shown a protective effect of flaxseed on both mammary and colon carcinogenesis. Significant relationships between urinary lignan excretion and cancer risk markers or tumor characteristics provide further support for a protective effect of flaxseed lignans in cancer. Flaxseed appears to be promising in regard to lowering the risk of cancer. Further information regarding its use in humans, its bioavailability, and mechanism of action is required.
