Hello, I would be grateful for your advice about soy proteins in skincare. I had a masectomy for lobular cancer (ER+ 8/8, Her-) and am now on letrosol, prostap and zolondronic acid. My Oncologist mentioned that I should avoid soya. I have just discovered that there appears to be some soy in some items I use on my face e.g. tinted moisturiser etc and I am worried about it. Do you know if there is any evidence that this can have an effect on estrogen in the body? Thank you so much.

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Hi @kwg

I’ve also asked questions about soy - I have been told and have read that although soy supplements should be avoided it’s apparently safe and possibly even beneficial to eat soy products. I eat tofu , soy sauce etc but I watch my intake and avoid soy milk which has given me problems before .
Soy seems to be in a lot of things so it might be hard to avoid it completely - I never thought to check my beauty products but I would have thought they would also be ok but I will read the Nurses reply with interest.

It can be hard to get your head around it all
Joanne. X

Hi Joanne,
I had ER positive BC for a year now. I was also hesitant before with soy because of the old myth that it could cause BC. But after watching Dr. Kristine Funk, Dr. William Li in the You Tube. I got a piece of mind that it’s safe to eat or drink foods with soy, or soy products like tofu. So I‘m suggesting that you watch Podcasts“ Exam Room with Chuck and you can really learn a lot of things how to take care of our selves after BC. I am in walking ( 30-45 minutes everyday or more. More on Plant-based foods too.
Wishing you all the best! Think positive & we will win this fight! God bless us!

Dear Joanne,

Thank you so much for your reply. It’s really helpful to hear about what you have heard about soy and reassuring as I imagine the amount in skincare must be quite small anyway. You are right - it is hard to get your head around it all!

Thank you for replying.

Best wishes,


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Hi @selecta

Thank you I will look into those suggestions . I do eat tofu and soya beans quite happily and I love Chinese food so have a lot of soy sauce , unfortunately soy milk does disagree with me so I avoid it. I’m also taking supplements that are not themselves soy but the capsules contain soy so I’m just trying to be careful. It’s a pity I can’t make myself be as careful with chocolate - I should probably watch the podcast you recommend !

On the plus side despite a couple of injuries I’m back to doing Yoga 3 times a week plus some cold water swimming and intermittent fasting .
Thank you for you lovely positive post Cher :blush:

Joanne. X

Hi so what I’m learning about soy is there’s a strong lobby pushing the soy products in almost everything we eat. So it could mean this is why there’s so much BC in almost every friend and family group out there. Maybe the soy production is now produced on tired over used soil, maybe the soy isn’t a healthy product as it was years ago. If it’s coming from GMO fields it’s definitely worth avoiding . The thing is how would we know which soy ingredients are not GMO, truly not. Most every single BC survivor I know is avoiding soy products as much as possible. The fact that you have Drs saying it’s ok, might be because the Soy lobby is extremely powerful. There s a growing evidence in young children developing breasts earlier and often in young boys. Because candies, sauces, spreads, oils, etc all come from soy fillers in endless amounts of premade foods.
Try avoiding it, and yes occasionally one can a little. I don’t obsess over avoiding soy but everyone I know in my part of the world, is definitely aware and avoiding it. Lots to learn…can’t believe everyone on any podcast, you don’t know who funds there programs.

Hello Katie

Thank you for your post.

Information about soy and breast cancer can be confusing and conflicting.

Soy contains isoflavones and lignans, which are weak phytoestrogens.

Phytoestrogens are naturally occurring plant substances that have a chemical structure similar to the female hormone oestrogen which is why there has been concern about its safety. But phytoestrogens are not the same thing as female hormones and don’t affect the body in the same way.

Soy food includes tofu, soybeans (edamame) and soy milk as mentioned here. Isoflavones are also found in other beans, nuts, peas and lentils and lignans are found in a variety of fruits, vegetables and cereal products.

There is no evidence that foods containing soy or isoflavones affects cancer risk in fact, there is emerging research that suggests it may be beneficial in reducing the risk of the cancer coming back. However, the safety of supplements containing soy is yet to be established so they are generally not recommended, as @JoanneN says.

We don’t know about the use of soy products in cosmetics, but it might help to know that in the UK the cosmetic industry has strict regulations in place. This information from the Cosmetic, Toiletry & Perfumery Association (CTPA) might be of interest.

It’s possible your oncologist was suggesting avoiding soy supplements rather than everything that has soy in it, including cosmetics, so do check with them again or perhaps your breast care nurse. Information doctors give is based on current clinical evidence such as that from the World Cancer Research Fund in the link above, rather than pressure or lobbying from organisations, which might need further research.

Information about causes of breast cancer can be found here.

You might be interested in the range of services we offer.

Do call our helpline if you would like to talk this through or have any further questions. The helpline team have time to listen to your concerns, talk things through and signpost you to more support and information. Your call will be confidential, and the number is free from UK landlines and all mobile networks. The number is 0808 800 6000, (Relay UK - prefix 18001).

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Breast Care Nurse

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Hi Kwg, I’m dairy intolerant and have been on Soya Milk especially for many years. My oncologist has not said i shouldn’t have, and i’ve had no adverse Side from either letrozole or zollondric acid, although i’ve only had one infusion of Zolondric because i pending having a tooth removed.

I’d suggest you contact the beauty co to find out their input, and considering all the other ingredients that go into face products, i’d be more concerned about them.
Unless you are specifically allergic to soya there should be no issue.
lol xxx

Dear Jane,

Thank you so much for your reply and all the very helpful information. I really appreciate you taking the time to respond so fully.

Best wishes,


Thank you so much x

Thank you so much for your reply.