Effects of flaxseed on breast cancer growth.

January 1, 2004 Human Health and Nutrition Data 0 Comments

Effects of flaxseed on breast cancer growth.

Year: 2004
Authors: de Lemos, M. O'Brien, R.K.
Publication Name: J. Oncol. Pharm. Prac.
Publication Details: Volume 10; Pages 145 – 147


The use of flaxseed (linseed) to combat breast cancer has attracted increased attention since the preliminary results of a clinical study were presented in the San Antonio Breast Cancer Symposium in December 2000. One of the most often quoted implications of the study was that the anti-tumour effect of flaxseed muffin may be comparable to that of tamoxifen. However, flaxseed also contains secoisolariciresinol diglycoside (SDG), which is converted by the gut bacteria into the oestrogenic lignans, enterodiol and enterolactone. Given that other plant-derived oestrogenic substances (phyto-oestrogens) can stimulate breast cancer growth under certain circusmtances, there are concerns regarding the safety of flaxseed. The following review will look at the existing data to help clarify some of these issues. (Author's Abstract)
This review indicates that, for the breast, anti-cancer effects of flaxseed are based on limited human and animal data, and may potentially interfere with their conventional cancer treatments. Although in vitro data suggest that flaxseed lignans may stimulate breast cancer growth, animal studies generally showed that dietary intake of flaxseed and flaxseed oil was associated with inhibition of breast cancer progression. In vitro data suggest the effects of flaxseed lignans on breast cancer growth may be concentration dependent: stimulation at lower concentrations but inhibition at higher concentrations. These seemingly contradictory effects of flaxseed lignans on breast cancer may be partly explained by different mechanisms involved.  The author suggests that the anti-tumour effects of flaxseed from animal and human data1 need to be interpreted with careful consideration.  Lignan levels in humans may be very different from those in animals due to interspecies difference. The implication that flaxseed may have similar anti-tumour effects on breast cancer as tamoxifen (as seen in some research) means that it may have similar potential in reducing the efficacy of cytotoxic chemotherapy. However, the interaction of the various components of flaxseed, when taken as whole food, on the kinetics and dynamics of phyto-estrogens on breast tumour growth is largely unknown.  (Editor's comments)

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