tomaxifen and soy

i was googling to see if my alcohol consumption interacted with tomaxefen. Could not find anything on alcohol but did find this bit about soy.

GENERALLY AVOID: Due to their estrogenic effect, isoflavones present in soy such as genistein and daidzein may stimulate breast tumor growth and antagonize the antiproliferative action of tamoxifen. Supportive data are derived primarily from in vitro and animal studies. In vitro, low concentrations of these phytoestrogens have been found to promote DNA synthesis and reverse the inhibitory effect of tamoxifen on estrogen-dependent breast cancer cell proliferation. In contrast, high concentrations of genistein greater than 10 microM/L have been found to enhance tamoxifen effects by inhibiting breast cancer cell growth. It is not known if these high concentrations are normally achieved in humans. Plasma concentrations below 4 microM/L have been observed in healthy volunteers given a soy diet for one month or large single doses of genistein. These concentrations are comparable to the low plasma concentrations associated with tumor stimulation reported in animals. In a study of 155 female breast cancer survivors with substantially bothersome hot flashes, a product containing 50 mg of soy isoflavones (40% to 45% genistein; 40% to 45% daidzein; 10% to 20% glycitein) taken three times a day was found to be no more effective than placebo in reducing hot flashes. No toxicity or recurrence of breast cancer was reported during the 9-week study period.

MANAGEMENT: Until more information is available, patients treated with tamoxifen may consider avoiding the consumption of soy-containing products.

Bother - I love chinese food and most contains soy sauce. I’ll have to do another of my risk/benefit/pleasure assessments!

I think the soy in soy sauce has been fermented and that gets rid of all the bad effects. Also I think by a soy diet they meant milk and other soy foods. Doubt if a splash of the good stuff will do much harm

Good answer!
And I hate tofu, so that’s ok…

Hello again you 2! I’m having homemade Chinese tomorrow, with my usual drink so you prob won’t be hearing from me again! Oldandlumpy, I’m on a high dose of thyroxine and no one has mentioned anything about link with alcohol or tamoxifen.

I’m braving the M6, M1 and M25 tomorrow - I still think that’s more dangerous!

Ditto DJ, I’ll do what I can, in moderation.

My Chinese take away makes my Chinese and misses out the soy for me! Egg fried rice without soy.
She goes as far as saying I cant have this or that, as she knows she is to watch out for me!
Have it in chocolate though…

Hi all

I’ve posted quite a bit on soy in the diet and research thread and looked into this a fair bit.
I think that one of the best reviews of the fors and againsts of soy is on the Memorial Sloan-Kettering Cancer Center website.

It points shows that some studies on animals show that soy can antagonise the effects of tamoxifen while another recent study showed that soy consumption in Chinese woman reduced mortality and recurrance regardless of tamoxifen use.

I think soy is a really difficult one because many of the studies have been done either in vitro (test tube) or on mice and often taking out certain elements of soy such as genistein (one of the phytooestrogenic components) rather than looking at a whole dietary consumption.

However, where the studies do show a positive effect such as the one with Chinese women, it isn’t clear what type of soy they were eating. In the West, we have a lot of processed soy such as soy milk and other soy products which is possibly quite different from what they have in China.
I also recently saw an academic paper showing that soy milk had a stimulating effect on breast cancer cells which was unrelated to any phytooestrogen element of the milk.

Soy Sauce - the Sloan Kettering article says that soy sauce doesn’t contain any phytooestrogens.

I have decided to keep soy in my diet very limited until there is better evidence. A lot of work is being done in this field at the moment so hopefully we’ll get clarity over the next few years.

My personal decision on soy is that I do use soy sauce and I wouldn’t worry about a bit of soy in my chinese takeaway, or a bit of tofu sometimes or even the occasional bit of soy milk but I wouldn’t have any of it on a regular basis. Elinda x

Thanks for the clarification Elinda.
I know that I’m alot more cavalier in my attitude to diet than you are, but it’s always nice to have a bit of reassurance.

Glad it was helpful. I’m not as virtuous as you think. I’m strict about certain things such as no dairy, limited alcohol and eating lots of veg but I have a lot of vices. Yesterday’s was a lovely apple crumble with oatly cream - yum!
I’ve got a friend who is healthy, slim and fit and if she fancies something sweet she eats one sponge finger biscuit (only 25 calories!). That’s what I call will power but seems a bit boring too. Elinda x