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QUESTION: I've just read that soy can increase the rate of breast cancer. Your A diet recommends quite a bit of soy. How do you reconcile your theories with these new studies?
ANSWER: This was from a BB post I left a few weeks ago:
Man bites dog? I know Stephen has posted till he was blue in the face on the subject, but two additional thoughts on why if soy causes cancer, it certainly doesn't do it in type A's:
1. The relatively low methionine levels in some phytochemicals such as soy, limit the synthesis of polyamines necessary for tumor growth(1). Methionine is problematic for type A's in other areas as well: it is linked to elevated levels of homocysteine, a significant risk factor for artery disease.
2. Genistein and daidzein, the major phytoestrogens in soy are themselves 'aromatase inhibitors.'(2) This is true of many isoflavones. Aromatase is an enzyme which converts androgens to estrogens by altering the ring structure of the steroid. Aromatase is located in estrogen-producing cells including ovaries, placenta, testicular Sertoli and Leydig cells, adipose, and brain tissues. Aromatase inhibitors are increasingly the drug of choice for managing metastatic breast cancers which have retained estrogen sensitivity.
This may explain why certain plant estrogen rich foods (such as alfalfa) have always been viewed by naturopaths as 'estrogen modulating' rather than 'estrogen elevating'; the phytoestrogens simultaneously act both as estrogens and aromatase inhibitors. The particular effect may be variable in the individual, and because aromatase is part of the liver's cytochrome p-450 system, it is intimately linked up with many detoxification functions.
This is important anti-cancer stuff for type A's.
1. AU Cline J M, Hughes C L Jr IN Bowman Gray School of Medicine, Department of Comparative Medicine, Comprehensive Cancer Center of Wake Forest University, Winston-Salem, NC 27157, USA TI Phytochemicals for the prevention of breast and endometrial cancer SO Cancer-Treat-Res 1998, VOL: 94, P: 107-34
2. J Steroid Biochem Mol Biol 1993 Sep;46(3):381-8 Flavonoid inhibition of aromatase enzyme activity in human preadipocytes. Campbell DR, Kurzer MS