Key Component of Flaxseed Has Cancer Fighting Potential
Flaxseed-derived lignans might offer protection against breast, prostate, colon, and skin cancers.
The soluble fibre they contain could help maintain steady blood sugar levels, found a review of research into the components of the nutrient-rich seed.
A report, published in Comprehensive Reviews in Food Science and Food Safety, evaluated current research on flaxseed and any potential benefits it may have against diabetes and certain cancers.
Flaxseed has been the focus of increased interest in the field of diet and disease research due to the potential health benefits associated with some of its biologically active components: oil containing approximately 59 per cent a-linolenic acid (ALA) and the presence of plant lignan secoisolariciresinol diglycoside (SDG).
The authors, researchers from Canada, England and China, summarized that the health benefits from flaxseed ligans are due to their antioxidant activity, primarily from hydroxyl radical scavengers and also due to the naturally-occuring estrogenic and antiestrogenic compounds and the structural similarity to 17-b-estradiol.
Their paper states that SDG, once ingested, is converted in the colon into active mammalian lignans, enterodiol (END) and enterolactone (ENL) which have shown promise in reducing growth of cancerous tumors, especially hormone-sensitive ones such as those of the breast, endometrium and the prostate.
They concluded that flaxseed lignans could be a significant part of a treatment regimen for cancer based on the large number of small scale studies but they stress that further research is needed in clinical settings to support the role of flaxseed in cancer prevention.
Studies on flaxseed benefits for breast cancer that the authors reviewed showed the presence of flaxseed lignans in MCF-7 tumors and observed lignan binding to estrogen receptors (ER). This suggests, said the reviewers, that the lignan function may be ER-mediated.
“Although the lignans have been shown to be protective against breast cancer, minor structural alterations may influence overall activity. Thus, many of the aforementioned benefits might be the results of specific structural features needed for lignans to bind to estrogen receptors” they claim.
Evaluating studies looking at flaxseed ligans effect on prostate cancer, the researchers said that lignans enterodiol and enterolactone were believed to be partly responsible for the growth inhibition of 3 human prostate cancer cell lines.
They report that previous research (1997) found that higher enterolactone levels in prostatic fluid were associated with populations with a low risk of prostate cancer.
Another small clinical study, note the reviewers, showed that prostate cancer cell proliferation decreased and apoptosis increased in men fed 30 g of flaxseed per day, and they reported that a subsequent study by the same researchers supported the role of flaxseed in combination with a low-fat diet as a means to control prostate growth.
Although not as extensively reviewed, the reviewers also report that flaxseed has been shown to inhibit colon and skin cancers in cell cultures and animal studies that have been conducted in this area.
Low-glycemic-index foods containing soluble fibre may not only prevent certain metabolic ramifications of insulin resistance, but also reduce insulin resistance, noted the authors, citing a study whereby flaxseed was shown to reduce the postprandial blood glucose response in humans.
“A consumption of 50 grams of ground flaxseed by young females over a 4-wk period caused a reduction in blood glucose levels (Cunnane and others 1993). Similar findings were observed in postmenopausal women fed a 40 grams of ground flaxseed fortification diet (Lemay and others 2002),” they stated.
Source: Comprehensive Reviews in Food Science and Food Safety (Published online)
Title: Flaxseed Lignans: Source, Biosynthesis, Metabolism, Antioxidant Activity, Bio-Active Components, and Health Benefits