Editor's note: This is an excellent review. Every man should want to know how cow milk causes prostate cancer should read the original article or at least the following report.
By David Liu, PHD
Monday Sept 3, 2012 (foodconsumer.org
) -- An excellent review recently published in Nutrition and Metabolism explains in detail that cow-milk increases risk of advanced prostate cancer, which has been observed in numerous studies.
Prostate cancer develops with androgen receptor signaling and aberrations of the PI3K-Akt-mTORC1 pathway, which is prompted by some nutrients to mediate excessive and sustained growth signaling, according to authors of the review Bodo C Melnik of University of Osnabrück in Osnabrück D-49090, Germany and colleagues.
Kinase mTORC1 is upregulated in nearly 100 percent of advanced human prostate cancer, and oncogenic mTORC1 signaling triggers key multiple subsets of mRNAs that participate in prostate cancer initiation and progression.
Kinase mTORC1 is nutrient-sensitive and can for instance be influenced by foods like dairy protein. Epidemiological studies have linked increased dairy protein consumption with elevated risk of developing prostate cancer. mTORC1 has been known as a master controller in the synthesis of proteins and lipids and autophagy pathways that couple nutrient sensing to prostate cancer cell growth, the reviewers say.
The current review, according to the authors, focuses on evidence that cow's milk but not human milk, promotes prostate cancer initiation and profession by stimulating mTORC1 signaling.
Mammalian milk intended for babies works in a sense as an endocrine signaling system, which activates mTORC1, promotes cell growth and proliferation and suppresses autophagy, which is why infants grow fast.
Milk-mediated mTORC1 signaling is naturally restricted only to the postnatal growth phase of mammals. But when men persistently consume cow-milk proteins, they obtain highly insulinotropic branched chain amino acids or BCAAs from milk's fast hydrolysable whey proteins. These amino acids in turn boost postprandial serum insulin levels, and elevate hepatic insulin-like growth factor - 1 (IGF-1) plasma concentrations.
High levels of BCAAs, insulin, and IGF-1 are critical in activating mTORC1 signaling. The reviewers say increased cow's milk protein or casein or whey-mediated mTORC1 signaling along with constant intake of estrogens from commercial cow's milk collected from pregnant cows may explain why high dairy consumption is associated with increased risk of prostate cancer in the West.
It should be pointed out that in the U.S., cows produce milk in more months than countries like Mongolia where milk with high levels of estrogen are not collected during certain period of lactation, according to a Mongolian scientist who revealed this when she gave a presentation to her colleagues at Harvard University.
A well-balanced mTORC1-signaling is important in normal prostate morphogenesis and differentiation, according to the reviewers. But when mTORC1 signaling is exaggerated by high cow's milk consumption, the critical yet otherwise normal growth phases of prostate glands could suffer long term adverse effects.
The authors say "contemporary Paleolithic diets and restriction of dairy protein intake, especially during mTORC1-dependent phases of prostate development and differentiation, may offer protection from the most common dairy promoted cancer (prostate cancer) in men of Western societies."
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