Soy's love hate relationship with cancer

genmail2000

Soy's relationship with cancer is conflicting and contradictory. One study reports that those who ate the most soy, which ranged from several servings a week to once a day, had a 40 percent lower risk of prostate, breast and uterine cancers.

Some researchers are of opion that that the weak estrogens in soy’s photochemicals could stimulate the development of precancerous cells or malignant cells of estrogen-sensitive cancers like breast cancer. Soy isoflavones and genistein cause estrogen stimulation of breast which could be a trigger for breast cancer in women.
 
But occurrence of breast cancer in predominantly soy consuming people like Japanese, Chinese and in South East Asia is indeed very low. This is because soy’s protection against breast cancer comes only when it is consumed before or around puberty. In Asia soy is a part of daily diet right from childhood. But for those women who consume soy much later in life the benefits may be limited or even counter productive when it comes to breast cancer. The applies to derivatives of Soy like tofu etc. You might want to reconsider your decision of starting of with soy products.

Husband11

I see you are promoting tumeric.  A question I have as yet to get an answer to is what the implications are for users of tamoxifen that take tumeric.  My understanding is that the metabolism of tumeric involves the cyp2d6 enzymes that tamoxifen is also dependant upon.  Could tumeric interfere with tamoxifen metabolism?

luv_gardening

Genmail, I see you've started several threads around your products, curcumin and resveratrol, which are being sold on your web site which you push on every occasion except your opening posts which you know will have you thrown off here.  One of your posts has already been deleted by the community as spam.

You give no personal history of having breast cancer or being close to somone who has BC.  If you have a personal BC story then please tell us?

luv_gardening

Timothy, that's an interesting question. 

I have to decide whether to switch to Tamoxifen from Arimidex as I recently found out I have osteoporosis. I also take curcumin supplements and cook with turmeric.  Do you have any links to confirm the cyp2d6 clash?  Every time I see the words Tamoxifen and metabolism together I get a bad feeling and wonder if my instincts are correct.

Thanks for your always valuable input.

Husband11

I'll have to do this in two steps of pasting and editing, first a link:

http://www.ncbi.nlm.nih.gov/pubmed/17433521

• Performing your original search, curcumin cyp2d6, in PubMed will retrieve 5 records.

Toxicology. 2007 Jun 3;235(1-2):83-91. Epub 2007 Mar 15.

Inhibition of human recombinant cytochrome P450s by curcumin and curcumin decomposition products.

Appiah-Opong R, Commandeur JN, van Vugt-Lussenburg B, Vermeulen NP.

Division of Molecular Toxicology, Leiden/Amsterdam Center for Drug Research (LACDR), Department of Pharmacochemistry, Vrije Universiteit, De Boelelaan 1083, 1081 HV Amsterdam, The Netherlands.

Abstract

Curcumin (diferuloylmethane) is a major yellow pigment and dietary component derived from Curcuma longa. It has potent anti-inflammatory, anticarcinogenic, antioxidant and chemoprotective activities among others. We studied the interactions of curcumin, a mixture of its decomposition products, and four of its individually identified decomposition products (vanillin, vanillic acid, ferulic aldehyde and ferulic acid) on five major human drug-metabolizing cytochrome P450s (CYPs). Curcumin inhibited CYP1A2 (IC(50), 40.0 microM), CYP3A4 (IC(50), 16.3 microM), CYP2D6 (IC(50), 50.3 microM), CYP2C9 (IC(50), 4.3 microM) and CYP2B6 (IC(50), 24.5 microM). Curcumin showed a competitive type of inhibition towards CYP1A2, CYP3A4 and CYP2B6, whereas a non-competitive type of inhibition was observed with respect to CYP2D6 and CYP2C9. The inhibitory activity towards CYP3A4, shown by curcumin may have implications for drug-drug interactions in the intestines, in case of high exposure of the intestines to curcumin upon oral administration. In spite of the significant inhibitory activities shown towards the major CYPs in vitro, it remains to be established, whether curcumin will cause significant drug-drug interactions in the liver, given the reported low systemic exposure of the liver to curcumin. The decomposition products of curcumin showed no significant inhibitory activities towards the CYPs investigated, and therefore, are not likely to cause drug-drug interactions at the level of CYPs.

PMID: 17433521 [PubMed - indexed for MEDLINE]

Publication Types, MeSH Terms, Substances Publication Types: In VitroResearch Support, Non-U.S. Gov'tMeSH Terms:Aryl Hydrocarbon Hydroxylases/antagonists & inhibitorsBenzaldehydes/pharmacologyCoumaric Acids/pharmacologyCurcumin/chemistryCurcumin/metabolismCurcumin/pharmacology*Cytochrome P-450 CYP1A2/antagonists & inhibitorsCytochrome P-450 CYP2D6/antagonists & inhibitorsCytochrome P-450 CYP3ACytochrome P-450 Enzyme System/antagonists & inhibitors*Cytochrome P-450 Enzyme System/geneticsCytochrome P-450 Enzyme System/metabolismDrug InteractionsDrug StabilityEnzyme Inhibitors/chemistryEnzyme Inhibitors/metabolismEnzyme Inhibitors/pharmacology*HumansKineticsOxidoreductases, N-Demethylating/antagonists & inhibitorsVanillic Acid/pharmacologySubstances:BenzaldehydesCoumaric AcidsEnzyme Inhibitorsferulic acidvanillinVanillic AcidCurcuminCytochrome P-450 Enzyme SystemCYP3A4 protein, humanAryl Hydrocarbon HydroxylasesCYP1A2 protein, humanCYP2C9 protein, humanCytochrome P-450 CYP1A2Cytochrome P-450 CYP2D6Cytochrome P-450 CYP3AS-mephenytoin N-demethylaseOxidoreductases, N-DemethylatingLinkOut - more resources

Husband11

Two things to note from the above:

 1) Research was done in vitro (ie outside a living organism) and given the unanswered question of whether or not curcumin concentrations in the liver are sufficient, its not known whether this observation results in an actual drug interaction;

2) Definition of non-competitive inhibition (for those interested):

Non-competitive inhibition is a type of enzyme inhibition that reduces the maximum rate of a chemical reaction (V_max) without changing the apparent binding affinity of the catalyst for the substrate (K_mApp in the case of enzyme inhibition, - see Michaelis-Menten kinetics).

Non-competitive inhibition usually applies to enzymes and differs from competitive inhibition in that the inhibitor always binds to the enzyme at a site other than the enzyme's active site (this other site is called an allosteric site). This affects the rate of the reaction catalysed by the enzyme because the presence of the inhibitor causes a change in the structure and shape of the enzyme. This change in shape means the enzyme is no longer able to bind with a substrate correctly (See lock and key hypothesis). This reduces the concentration of 'active' enzyme resulting in a decrease in the V_max. In this mode of inhibition, there is no competition between the inhibitor and the substrate, so increasing the concentration of the substrate still does not allow the maximum enzyme activity rate to be reached.

Key point being that you can't simply take more tamoxifen to make up for the inhibitor where the inhibitor displays non-competitive inhibtion of the enzyme, cyp2d6.