22 November 2019

Two types of soy receptors and how they affect your cancer risks

Perhaps more than anything else to do with food, people ask me about the cancer risks associated with soy. Is it safe? Is it dangerous? Is it even helpful?

Well, the research gets clearer and clearer, while the social media and some health practitioners seem to get more and more confused. So this week, vital new insights into why soy acts the way it does – and what that means for our health, plus details of Ruth's pre-Easter meditation retreat with Melissa Borich that I will be joining next year - April 3rd - 9th, but first

       Thought for the day   

Meditation enables me to feed myself - the soul 
With spiritual knowledge that gives me 
The experience of peace, purity, wisdom, love and lasting happiness. 

It gradually restores in me the confidence and dignity 
To live in the light of my original nature 
And awakens hope in the self.

                         Sister Jayanti

One thing is certain, oestrogen is not all bad. It is the main female hormone and is closely tied to so many of women’s wonderful qualites. Men produce it too but in much smaller quantities (just as women produce some testosterone). Also, oestrogen does reduce menopausal symptoms, improve bone health, and reduce hip fracture risk.

However, oestrogen clearly also has a dark side. It is associated with increasing blood clots in the heart, brain, and lungs, and more troubling still, with breast cancer.

How oestrogen has its effect is due to the fact various types of cell within our bodies have receptors on their surfaces that respond to oestrogen.

When oestrogen comes in contact with these external receptors, an internal reaction is triggered that in bone tissue is healthy, in breast tissue - unhealthy!

Now the old theory related to breast cancer risks – one I have shared a lot - is that phyto-oestrogens, plant based oestrogens like genestein in soy beans, compete with a woman’s own estrogens, effectively block the natural oestrogens and in doing so inhibit breast cancer growth. In this theory, the oestrogen-blocking ability of phytoestrogens explained their unhelpful effects, yet can we explain their helpful effects on other tissues like bone?

So here is where both the body and plants are so amazing. First the body. Recent research has established there are 2 types of oestrogen receptors. The recently discovered ones are being called estrogen receptor beta…to distinguish them from the ‘classical’ oestrogen receptor alpha”.

As for the plants, soy phytoestrogens preferentially bind to the beta receptors, and you can probably guess… the beta receptors have the positive effects; the alpha receptors the unhelpful effects.

Natural oestrogen from the body tends to bind to the alpha receptors.

What does this all mean in real life? If you say eat a cup of soybeans or its equivalent in natural soy products like tofu, there is very little alpha activation, but lots of beta activation.

By contrast, chemical oestrogen supplements increase the risk of fatal blood clots by causing the liver to release high amounts of clotting factors. And again, you can probably guess – our livers contain only alpha estrogen receptors, not beta receptors. In theory if you ate a huge amount of soy – like 30 cups (as maybe you might in a concentrated supplement) well that could be a problem but at the concentrations associated with normal soy consumption, no problem.

The effects on the uterus also appear to be mediated solely by alpha receptors, which is presumably why no negative impact has been seen with soy. So, while oestrogen-containing drugs may increase the risk of endometrial cancer up to ten-fold, phytoestrogen-containing foods are associated with significantly less endometrial cancer. In fact, protective effects are recorded for these types of gynaecological cancers in general: a study showed women who ate the most soy had 30% less endometrial cancer and appeared to cut their ovarian cancer risk nearly in half.

Soy phytoestrogens do not to have any effect on the lining of the uterus and can still dramatically improve some menopausal symptoms.

In what is probably the most robust study to date, researchers compared the soy phytoestrogen
genistein to a more traditional hormone replacement therapy (HRT) regimen.

 Over one year, in the spine and hip bones, the placebo group lost bone density, while it was gained in both the soy phytoestrogen and HRT estrogen groups. The “study clearly shows that genistein prevents bone loss…and enhances new bone formation…in turn producing a net gain of bone mass.”

The main reason we care about bone mass is that we want to prevent fractures. Is soy food consumption associated with lower fracture risk? Yes. In fact, a significantly lower risk of bone fracture is associated with just a single serving of soy a day, the equivalent of 5 to 7 grams of soy protein or 20 to 30 milligrams of phytoestrogens, which is about a cup of soymilk or, even better, a serving of a whole soy food like tempeh, edamame, or the beans themselves.

Fracture data has not been determined for soy supplements. “If we seek to derive the types of health benefits we presume Asian populations get from eating whole and traditional soy foods,” maybe we should look to eating those rather than taking unproven protein powders or pills.

Finally, is there anyone who should avoid soy? Yes, if you have a soy allergy. That isn’t very common, though. A national survey found that only about 1 in 2,000 people report a soy allergy, which is 40 times less than the most common allergen, dairy milk, and about 10 times less than all the other common allergens, such as fish, eggs, shellfish, nuts, wheat, or peanuts.

Happy eating


Ruth has asked me to contribute to the meditation retreat she will present with Melissa Borich pre-Easter next year. Not possible to refuse, so looking forward to being involved once again and joining these two extra-ordinary women.

Here is the link to Reclaiming Joy : 3rd – 9th April 2020


Is soy safe – Part 1 

Is soy safe – Part 2

The latest on soy and breast cancer