The primary benefit of lignan consumption is to increase blood levels of enterolactone. Enterolactone is produced during the metabolism of plant lignans by the intestinal bacteria. Scientists have conducted extensive research to ascertain why enterolactones are so effective against prostate and other cancers.
A number of studies show that the increase in estrogen that occurs in aging men is a culprit in the development of both benign prostate enlargement and prostate cancer.20-23 Enterolactone functions via several mechanisms to reduce estrogen levels.
Enterolactone inhibits the aromatase enzyme that is responsible for converting testosterone into estradiol (a potent estrogen).24,25 Aging men often take expensive aromatase-inhibiting drugs (such as Arimidex�) to improve sexual performance, desire, and satisfaction and to help lose belly fat. By inhibiting the aromatase enzyme, aging men can reduce excess estrogen while simultaneously increasing beneficial free testosterone. Higher free testosterone levels have been shown to reduce the risk of a number of age-related disorders.26-30
Enterolactone may also reduce estrogen levels by inhibiting its binding to its primary protein carrier called sex hormone-binding globulin (SHBG). This enables the liver to more efficiently accelerate the natural metabolic clearance of estrogen.31
Among the three major estrogen hormones (estrone, estradiol, and estriol) produced by the human body, estradiol (E2) is the most potent, and its levels are often too high in aging men�s bodies. Enterolactone inhibits the enzymes called 17-beta hydroxysteroid dehydrogenases (HSDs), which are responsible for the conversion of estrone (E1) into estradiol (E2).32
Another enzyme involved in both benign and malignant prostate disease is 5-alpha reductase. The 5-alpha reductase enzyme converts beneficial testosterone into a potent metabolite called dihydrotestosterone (DHT). DHT provokes a potent stimulatory effect on both benign and malignant prostate cells.33
The reason Life Extension has long recommended FDA-approved drugs like Proscar� and Avodart� is that they inhibit 5-alpha reductase and thus lower DHT levels. (Avodart� is more effective than Proscar�, but consumers can now purchase a much less expensive generic version of Proscar� called finasteride.)
The enterolactones have been shown to inhibit 5-alpha reductase,34 thus reducing levels of DHT, which causes so much prostate discomfort in aging men. We still don�t know exactly how effective the ingestion of plant lignans (and their subsequent conversion to enterolactones) will be in lowering DHT. Men who are prescribed Proscar� or Avodart� should continue taking their drug until we know for certain how much DHT reduction will occur in response to ingestion of standardized plant lignans.
Cancer cells utilize the tyrosine kinase enzymes to fuel their rapid growth. Metastatic prostate cancer cells were shown in one study to overexpress tyrosine kinases by 10- to 100-fold as compared with normal prostate epithelial cells.35 Enterolactone helps to inhibit the tyrosine kinase enzyme.36
Finally, enterolactone has been shown to inhibit angiogenesis (growth of new blood vessels into tumors) and promote cancer cell apoptosis (destruction) in animal models of hormone-related cancers, such as prostate cancer.37,38
LOCARNO, SWITZERLAND & EASTON, PA (May 14, 2008) -- A newly published study has shown a direct link between hydroxymatairesinol and the inhibition of prostate cancer cell proliferation by raising circulating enterolactone levels.
The study entitled, “Enterolactone restricts the proliferation of the LNCaP human prostate cancer cell line in vitro,” examines the molecular mechanisms by which enterolactone may influence LNCaP proliferation. The study was published in Molecular Nutrition & Food Research.
According to the researchers, their latest study demonstrates clearly that a pure lignan inhibits prostate cancer proliferation, and they believe that this is the first study to examine the correlation between the expression of genes associated with prostate cancer growth, and biological end-points of proliferation in vitro.
The selection of the enterolactone concentration used in this study was based on previous work that investigated the potential bioactivity of matairesinol, secoisolariciresinol, enterolactone and enterodiol in the PC-3, DU 145 and LNCaP human prostate cancer cell lines.
The study found that treatment with a subcytotoxic concentration of enterolactone (60 lM for 72 h) reduced:
►cell density (57.5%, SD 7.23, p a 0.001)
►metabolic activity (55%, SD 0.03, p a 0.001)
►secretion of PSA (48.50% SD 4.74, p = 0.05)
►and induced apoptosis (8.33-fold SD 0.04, p = 0.001) compared to untreated cells. Co-treatment with 10 lM etoposide was found to increase apoptosis by 50.17% (SD 0.02, p a 0.001).
Additionally, according to the authors, the data suggests that the anti-proliferative activity of enterolactone is a consequence of altered expression of cell cycle associated genes and provides novel molecular evidence for the anti-proliferative properties of a pure lignan in prostate cancer.
Epidemiological research strongly suggests that a long-term diet rich in lignans can significantly suppress the development of prostate cancer in men. The study quotes, “The capacity of a pure mammalian lignan, enterolactone, to influence the proliferation of the LNCaP human prostate cancer cell line was investigated as a function of cell density, metabolic activity, expression and secretion of prostate specific antigen (PSA), cell cycle profile, and the expression of genes involved in development and progression of prostate cancer.”
A previous study performed at the Department of Clinical Medicine at the University of Insubria in Italy revealed that in vitro, the viability of human prostate cancer cells is impaired by the lignans’ enterolactone and, to a lesser extent, hydroxymatairesinol.
“This latest study bodes well for men who are concerned about developing prostate cancer and whom are looking to help offset that risk with natural therapies,” said Robin Ward, Vice President of Linnea. “We encourage further research of the effects and efficacy of hydroxymatairesinol and enterolactone as it relates to addressing prostate cancer.”
HMRlignan™, derived from Norway Spruce (Picea abies), has the highest sustainable concentration of 7-hydroxymatairesinol. “As such, it is the most economical and qualitative source for dietary supplements and functional foods," explained Ward. "As continued research substantiates the benefits of HMR to boost enterolactone levels, HMRlignan™ remains the far superior choice for products geared to men and women who are concerned about raising enterolactone to healthy and sustainably viable levels to assist in cardiovascular protection and protection against development of breast cancer and, as this latest study shows, prostate cancer."
How Lignans Protect Against Prostate Cancer
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