Soy protein or soy isoflavones have a protective effect in women with breast cancer reducing recurrence and increasing survival.
Researchers from the Epidemiology Center at the Vanderbilt Medical Center in Nashville, alongside researchers from the Preventative Medicine Centre in Shanghai, set out to find the truth about soy use in breast cancer patients. Soy food intake was measured as ‘any soy protein or soy isoflavone intake’, fermented or not, made no difference. 5,042 breast cancer survivors were studied. Soy food intake was inversely associated with recurrence and mortality (1).
Chris Woollams, former Oxford University Biochemist said, “Many ill-informed people including people working in hospitals, tell women with Er+ve breast cancer to avoid foods and supplements containing phytoestrogens –resveratrol, flaxseed and especially soy – because they increase women’s oestrogen levels. But this is totally inaccurate – plants contain no harmful oestrogen like the human oestrogen, oestradiol. Put it even more simply, there are good and bad oestrogens, like good and bad fats.
Oestrogen is actually a family of compounds competing with each other for receptor sites. So phytoestrogens can sit on receptor sites blocking the ability of nasty human oestradiol to sit there and create havoc inside the cell. Genestein is in Red Clover, the herb of Hippocrates, and soy. Professor Trevor Powles of the Royal Marsden when he was head of breast cancer actually did research and showed genestein could block the receptors, preventing the damaging effects of oestradiol. Oestradiol is about 40 times stronger than oestrone which is about 50 times stronger than phytoestrogens.
Phytoestrogens are a diverse group of natural polyphenols in broadly three groups:
- Coumestrol - found in alfa-alfa, spinach, beans and soybean sprouts, and clover sprouts;
- Isoflavones and flavones - found in red grape skins (resveratrol), quercetin and peanuts;
- Lignans – found in flaxseed, sesame seeds, nuts such as cashews, whole grains, and fruit such as berries
They are known to reduce atherosclerosis, osteoarthritis, diabetes and angiogenesis in cancer (2).
Concentrations of isoflavones are particularly high in soy.
The other well quoted non-science ‘fact’ is that ‘Soy blocks Tamoxifen’. In fact, the opposite appears true according to the research. In laboratory and in vivo studies, soy improves the blocking action of Tamoxifen (3)
In one review of 131 research articles it was noted that, “Soy consumption may be associated with reduced risk of breast cancer incidence, recurrence, and mortality. Soy does not have estrogenic effects in humans. Soy intake consistent with a traditional Japanese diet appears safe for breast cancer survivors. In most of these studies, a significant proportion of the study participants were taking tamoxifen”.
Soy and red clover isoflavone improves breast cancer survival and reduces recurrence, with or without Tamoxifen (4).
Go to: Atorvastatin increases breast cancer survival
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References
- Soy Food Intake and breast cancer survival; JAMA. 2009 Dec 9; 302(22): 2437–2443.
- Book: Reproductive and Developmental Toxicology,; Michelle Mostrom, Timothy J. Evans
- Oncology Nutrition
- Soy, red clover and isoflavones in Breast cancer; Fritz H, Seeley D et al