If there’s one topic that’s guaranteed to get people arguing (other than vaccination!) it would have to be soy.  Go on a Googling safari and you’ll find plenty of articles stating the ‘dangers of soy’ and then others that take a completely different point of view, and explain how soy can be good for you.

So, who is right?  Well, both, in a way.  So let me explain why.

I decided that it was time to give my take on the matter, and address all aspects of soy – the good, the bad and the potentially ugly.  So, here goes….

The Good:

First off, we need to recognize that soy has been around for a loooong time.  Without question, it has played a significant role in the human food supply for thousands of years, mostly in Asian countries such as China and Japan.   Compared to many other legumes (members of the bean family), soy is quite high in good-quality protein, which means when you eat soy (particularly if you are a vegetarian), you get a lot of ‘bang for your buck’.  The beans can be used the basis of many meals, and they are also commonly eaten as tofu (bean curd), tempeh and miso soup.  So in other words, soy has a long, well-established history of being safe and nourishing to eat.

More recently, soy has been scientifically researched to see if it potentially holds benefits for certain health conditions – and it has been found to do so.  In particular, it has been shown to help reduce the frequency and severity of hot flushes during menopause.1  It has also been shown to reduce the risk of female hormonal cancers – in Asia where soy is frequently eaten, women have lower rates of breast and endometrial cancer.2   Soy has also been shown to help preserve healthy strong bones after menopause, which is very important for reducing (or avoiding) the risk of osteoporosis.3

The Bad:

If you have a problem with your thyroid gland (particularly hypo/low function) then overdoing the soy is not necessarily a good thing.  Soy is a ‘goitrogen’ – meaning that it can interfere with the function of the gland.   Remember, your thyroid controls your metabolism, so if your metabolism is low and you are already suffering one or more of the many symptoms of low thyroid function, then you really don’t want anything worsening this.  However, it does appear that it is takes a certain amount of soy to become a problem – in general, moderate amounts of soy being eaten here and there aren’t going to be an issue.

In addition, the issue with soy affecting the thyroid mostly appears to be a problem if you are low in iodine – the main mineral that is needed by the thyroid to make hormones properly.4   Iodine is found mostly in seafood such as fish and seaweed (eg nori sheets used in sushi).  So if you are concerned about eating soy, make sure you are also eating some seafood regularly – at least 2 or 3 times per week, and/or taking a vitamin and mineral supplement that contains the Recommended Daily Intake (RDI) of iodine.

The Ugly:

Unfortunately, soy was one of the first crops to become a ‘GMO’ (genetically modified organism).  This means that genes from another species were added to the soy, to create plants that could withstand the application of glyphosate herbicides.  In other words, when a crop is ready to be harvested, the entire field can be drenched with chemicals that kill all the weeds, leaving the nice, shiny soy plants standing, in order to make harvesting a lot easier.  Now, whilst I’m sure we all want farmers to have as easy a job as possible (after all, they DO provide us with the food we eat every day), personally, I don’t believe this should come at the cost of our health!  It doesn’t take a rocket scientist to realize that by applying high levels of poisons to our food, some of it is going to remain in that food when we (and our children) eat it.

Also, keep in mind that soy is an ingredient in a LOT of things – including many of the products you are already buying in the supermarket, such as ‘vegetable’ oils, margarine, ‘vegetable protein’ and packaged foods (for instance, ‘lecithin’, a common additive, is often sourced from soy).

The best way to skirt this problem is to obviously fill your trolley with mostly fresh and unprocessed foods, but also if you are buying a soy product to choose organic – in Australia, any product that has the organic ‘bud’ symbol cannot be genetically modified, and also will not be sprayed with glyphosate chemicals.

Lastly, the confusion:

The final point I would like to make in this article is that one of the bad raps soy receives is due to its reputation as a ‘phyto-oestrogen’, meaning that has the potential to act a bit like an oestrogen (female hormone) in the body.  This has led to quite a bit of misunderstanding about whether soy should be avoided by males (as they probably don’t want any female hormones floating around in their body!), and whether it could be dangerous to females in a similar way to synthetic oestrogens (eg hormone replacement therapy/HRT increase risks of certain cancers).

Actually, the fact is that soy and other phyto-oestrogens don’t actually work the same way as synthetic hormones do – it is thought that they provide benefit by exerting an effect on the hormone receptor on cells.  Which is kind of like flicking a switch, but without contributing additional oestrogen.   The best part about phyto-oestrogens (and many similar herbal medicines) is that they ultimately provide a balancing effect that synthetic hormones just can’t do – if hormones are low, they can help to bring them up (for example, in menopause, where oestrogen is low), and if hormones are too high (for instance, in oestrogen-driven conditions such as endometriosis), they can help to lower things back down to where they should be.  And in case you were wondering, soy appears to be fine for men as well, with no evidence of it messing with male hormones!

So, in a nutshell – it’s time to stop being afraid of soy, as it can be a beneficial and nourishing food to eat, PROVIDED it is organic and as unprocessed as possible.

Braun, L. & Cohen, M.  (2015).  Herbs & natural supplements: Vol 2. An evidence-based guide (4th ed).  Sydney: Churchill Livingstone.
2 Lu LJ, et al. Increased urinary excretion of 2-hydroxyestrone but not 16alpha-hydroxyestrone in premenopausal women during a soya diet containing isoflavones. Cancer Res. 2000 Mar 1;60(5):1299-305.
3 Park CY, Weaver CM. Vitamin D Interactions with soy isoflavones on bone after menopause: a review. Nutrients 2012;4:1610-1621
Sharma R, et al. Diet and thyroid: myths and facts. J Med Nutr Nutraceut, 2014;3:180-185


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