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To Eat or not to eat: Soy

Updated: Jul 13, 2018

Every since the milk phobia began a few years back, milk alternatives have been flying off the shelves. In fact, a 2014 article in Food Business News stated that dairy alternatives saw a 36% increase in sales that year, with almond milk leading the way. 

Among these dairy alternatives is soy, which has become one of the most controversial foods among consumers. Some have labeled it a superfood, yet others have stayed as far away from the stuff as possible. So, who’s right? 

Psst… What’s the soy debate all about, again?

Advocates of soy tend to highlight its alleged ability to decrease one’s risk of cardiovascular disease and osteoporosis while protecting against hot flashes, menstrual symptoms, and even certain types of cancers. But soy-bashers vehemently disagree, stating that soy is a pesticide-rich food that affects hormone functioning, specifically when it comes to the thyroid. Let’s look at what the evidence says on each of these points.  

Myth Buster #1: Is Soy Filled with Pesticides? 


Roundup is the most widely used weed killer for many of Canada’s biggest crops like canola, soybean, field corn, and wheat. But farmers eventually noticed that Roundup kills the soybean plant. The solution? Why, to genetically modify the soybean of course! By genetically modifying the plant, soybeans were resistant to the main ingredient in Roundup and  farmers could abundantly spray their fields without destroying the crop. 

Myth Buster #2: Does Soy Disrupt Normal Hormone Functioning? 


To answer this question, we first need to talk about what isoflavones are. These are a specific type of plant estrogen, or “plant compounds that have estrogen-like structures.”

Isoflavones are so similar to estrogen in that they’re able to fit into the receptor site that’s normally taken up by naturally-made estrogen in the body. Because of its ability to mimic this natural hormone, soy is said to interfere with the creation, transportation, and metabolism of natural hormones in the body.

In reality though, it’s not so simple: Isoflavones might be similar to estrogen in their structure, but that doesn’t necessarily mean they act similarly. Without getting too technical, isoflavones are selective estrogen receptor modulators, meaning they have estrogen-like effects in some tissues, anti-estrogen effects on others, and no effect at all on some. In terms of the processes they do affect, some studies have confirmed that soy can increase the length of menstruation in pre-menopausal women and slightly reduce levels of FSH and LH—hormones necessary in reproduction. The repercussions of this are yet to be determined though. Additionally, isoflavones have demonstrated a to have a protective effect  against hormone-dependent cancers.

Myth Buster #3: Does Soy Impair Thyroid Functioning, Specifically? 


According to a research review done in 2006, soy protein has little to no impact on one’s thyroid functioning… if their thyroid is working well in the first place. The story is a bit different for people who have under-active thyroids. An article in Environmental Health Perspective showed that isoflavones might impair the enzymes needed to produce thyroid hormones. And even though eating soy itself doesn’t cause an under-active thyroid, eating lots of it while also being deficient in iodine could. In other words, if you have an under-active thyroid and aren’t getting enough iodine, you shouldn’t be gorging on soy. 

Myth Buster #4: Does Soy Block the Absorption of Other Nutrients? 


Soy contains something called phytic acid. This can reduce one’s ability to absorb the minerals calcium, zinc, magnesium, and iron, “thereby creating the potential for multiple nutritional deficiencies”. That being said, if you maintain a well-balanced diet and eat soy in moderation, this shouldn’t be a problem. Keep in mind that a lot of foods contain phytic acid too, including seeds, nuts, legumes, and cereal grains. To help decrease the amount of phytic acid, I'd recommend soaking legumes for at least 12 hours before preparing/consuming them. But remember, if you were to avoid foods solely because of phytic acid, you’d be missing out on a whole lot of other health benefits! 

The Bottom Line

When reviewing the research on soy products, I was overwhelmed with the amount of conflicting findings. It seems as though the main conclusion derived by researchers is that, well, research is inconclusive. So, when deciding on whether or not to eat soy, I like to take a similar approach as Dr. Hyman, a well-known, nutritionally-savvy physician. As he writes on his blog, “The dangers of soy are overstated. The benefits may be too.” Follow these tips to ensure the benefits of soy outweighs the risks: 

1. Don’t gorge on soy like a psychopath. The average dose of soy in many studies examining its effects was 36g of soy protein per day. That’s equal to eating more than one pound of tofu per day or about three soy protein shakes. That’s like studying the effects of caffeine on someone who has 10 cups of coffee per day… Obviously you’re bound to see some side effects! As with any food, it’s important not to over-do it. 

2. Enjoy organic soy that hasn’t been genetically modified and consume it in moderation—one to two servings per day. The soy milk brand Silk is a good option, as its certified non-GMO and also carrageenan-free (note: carrageenan is an additive suspected of contributing to gastrointestinal inflammation). 

3. Opt for fermented soy like miso, tamari, and tempeh. Fermentation destroys phytic acid and isoflavones, which your body may have a hard time digesting. It’s worth mentioning that soaking also greatly helps improve the digestibility of soy beans and other soy products, so soak some organic, non-GMO soy beans well if you’re using them in a dish.

4. Up your iodine intake if you’re concerned about soy’s effect on your thyroid.Enjoy sea vegetables like kept or iodized salt. 

I personally have no issue consuming soy products, so long as they’re non-GMO, organic, preferably fermented, and eaten in moderation. Also, I'll engage in soaking if I'm using soy beans in a meal.

You Tell Me!

Where do you stand? Do you love soy or hate it? Did this post change your opinion? Let me know in the comments below!  


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