I get questions about soy and low-thyroid almost weekly, so I thought it was about time that I did a deep dive into this issue, and provide you with some answers based on evidence-based science.
For the record, I didn’t used to be a fan of soy. I had read all the anti-soy propaganda, without doing a deep dive into the evidence-based science. And since doing the detailed research, I know have come to the conclusion (or rather science has come to the conclusion), that soy does more good than harm! This is rather gratifying to me because I love soy products as they pack a powerful protein punch into a whole-food plant-based diet.
But before I go further into the thyroid and soy issue, let’s get a couple of things straight. First off, your soy products need to be organic. And secondly, you want to try to limit the amount of highly processed soy products you eat – many of which are presented to us in the form of fake meats and such. Read my article about my take on fake meat. The least processed form of soy would be organic edamame beans, then next up would be tempeh, then tofu and soy milk.
Protein and versatility benefits aside, the reason why I incorporate a little soy into my diet everyday is that I am post-menopausal, and studies are showing me that soy phytoestrogens may prevent bone loss, and even enhance bone formation. Soy may protect me against a number of different cancers. And soy also dramatically improves menopausal symptoms (I barely had any).
In terms of the soy and breast cancer situation, which many woman are understandably very concerned about, there are five studies that have been performed on breast cancer survival and soy foods involving more than 10,000 breast cancer patients. And, those who ate more soy lived longer, and had a lower risk of the cancer coming back. This was especially true for woman who carry the BRCA gene.
So, let’s get to the thyroid issue. After reviewing all the literature and cited research papers to date, and comparing them, it seems that soy will not affect your thyroid negatively, but the caveat being that you must get enough iodine while you’re enjoying your soy. Iodine is vital for optimum thyroid function. But don’t go crazy because you want a balance – enough, but not too much.
The best way to get your iodine is to eat sea veggies. Also, I find that getting our nutrients from food generally affords the right amount of the said nutrient. I doubt anyone’s going to eat buckets of seaweed daily. A great way to get your daily seaweed is to substitute your table salt with Kelp granules. Nibble of a few sheets or Sea Snax and you’ll be good to go. The only sea veggie I recommend you avoid is Hijiki as it contains too much arsenic. Try Kelp, Kombu, and Nori. If you hate the taste of seaweed, you could take a supplement such as Sea Veg.
Studies have also found a close connection between selenium and thyroid function. I recommend eating 2-3 Brazil nuts a day. That should take care of your selenium needs, and you can just pop them in your smoothie.