Soy What? Debunking The Anti-Soy Health Myths

Andy the RD

In my five plus years of private practice dietetics I have been hard to pressed to find a client who has had a positive opinion or perception of soy-based foods.

Before they met me, that is.

Men often won’t eat them because they have heard that it will affect their testosterone levels.

Women won’t eat them because they harbour fears over an increased risk of breast cancer.

As the hyperlinks suggest, I’ve written articles dispelling both of those myths already.

In my experience, both genders seem to be equally repulsed by the thought of cooking with or eating tofu and it appears that nut-based milks are displacing and outnumbering soy milk on grocery store shelves ( at least my local grocer!).

So where does that leave me?

As a dietitian, one of the biggest challenges I face on an individual and population education level is convincing people that one of the absolute keys to good health is replacing at least a portion of their animal-protein intake with plant-protein ( Check out my article here to learn more).

This is a big enough challenge as it is, but it becomes even harder when all soy-based foods are arbitrarily ruled out of people’s diets for reasons other than a potential allergy/intolerance ( which is inevitably a relative small portion of the population).

Soy What?

I’m not going to go all Game Changers on you, but let’s be real here – Soy does have a secret power!

It is an exceptional alternative, from a nutritional perspective, for both meat and dairy.

Incorporating commonly available soy-based foods ( soy milk, tofu, soybeans, tempehedamame, soy nuts) is an excellent way to get protein, iron, calcium and healthy fats into your diet – all from plant sources.

Relying more on plant-based protein has serious benefits for your cardiovascular health – as demonstrated by the inclusion of soy in a famous cholesterol lowering diet – the  Portfolio Diet.

In my estimation, the inclusion of soy milk and tofu in the diet of the average person represents one of the most plausible means of increasing the intake of plant-based protein while simultaneously lowering the consumption of animal products. 

Tofu, in particular, can be manipulated and enhanced in the kitchen such that it truly is a superb meat-protein alternative both in terms of nutritional value and palette sensation.

Don’t believe me? Check out this tofu scramble recipe.

Sounds good so far right? You’d think so… but there are so many people out there who fear consuming soy. Why is that?

Why The Fear Over Soy?

Soy contains estrogen-mimicking compounds known as isoflavones (also known as phytoestrogens)  which operate in a mildly similar way to the female hormone estrogen.

I’ve explained previously why this is largely a non-issue.

What has happened, however, is that people seem to have latched onto this idea that soy intake profoundly impact hormone levels in the human body and thus should be avoided.

There is no strong evidence that I have come across to show this to be the case.

Oh, and some people also try to suggest that growing soy is bad for the environment and that all soy is GMO and must be avoided at all costs.

I’ve also previously explained why both of those arguments against soy are false.

Unfortunately, the popular media and  would-be scholars  often end up citing studies that are either inapplicable to humans, inconclusive or of unacceptable quality to support the claim that soy is bad for you and they use these studies, in part, to spin a dark tale on the harms of soy.

When we take a look at the highest quality aggregate evidence available on the impact of moderate soy consumption on human health outcomes, we see largely positive or ( at worst) neutral effects.

Think Soy Is Bad For You?

I took it upon myself to track down some  of the best aggregate evidence available on soy and health outcomes.

Let’s take a look:

For Men

1. Soy does not lower testosterone levels in men: There have been undue fears that soy somehow had a negative impact on male testosterone. This is quite simply an unfounded claim. There is, in fact, no strong evidence that soy has any meaningful effect on hormone levels in men. Don’t sweat it guys, having some tofu won’t make you any less of a man.   More on this topic on my latest article -> here.

2. Soy intake may reduce prostate cancer risk in menProstate cancer is the #1 most commonly diagnosed cancer in Males in North America and the consumption of soy-based foods is associated with a reduction in your risk.

3. Soy intake will lower your cholesterol Men (& women) in North America are commonly medicated for elevated LDL cholesterol levels. Having just written a book on cholesterol lowering, I fully appreciate how big of a public health concern it is.

For Women

1. Soy has a protective ( or at worst neutral) effect on breast cancer risk: There is a massive misconception out there that woman should avoid soy because it increases their risk of breast cancer. The best available evidence suggests that, in most cases, consuming soy products may actually be protective against breast cancer.

  • Chen et al found that soy intake was protective against breast cancer in Asian countries, but this effect was not found in Western countries.
  • Fritz et al Soy consumption may be associated with reduced risk of breast cancer incidence, recurrence, and mortality. Soy does not have estrogenic effects in humans. Soy intake consistent with a traditional Japanese diet appears safe for breast cancer survivors.
  • Messina And Loprinzi Overall, the data are not impressive that the adult consumption of soy affects the risk of developing breast cancer or that soy consumption affects the survival of breast cancer patients. Consequently, if breast cancer patients enjoy soy products, it seems reasonable for them to continue to use them.
  • Trock et al  found that soy intake may be associated with a small reduction in breast cancer risk.

Much more on the topic of soy & breast cancer can be found here.

2. Soy intake may reduce the risk of other women’s cancersA review of the best available studies have shown that women who eat more soy  tend to have a lower risk of ovarian and endometrial cancer.  Further evidence also suggests that women who consume more soy may be  protected from both colorectal and gastrointestinal.

3. Soy has no known negative effects on postmenopausal womenFor all the talk about soy products “tampering” with female hormones leading to ill effects, there is no evidence to suggest that this is the case at all based on the latest data.

4. Soy intake may help with PCOS: Experimental studies show that soy intake may help reduce insulin resistance and circulating levels of androgens in women living with PCOS.

Final Thoughts

No detractor of soy will be able to produce high quality aggregate evidence that it is dangerous for human consumption, because that evidence simply does not exist. 

Again, I believe that introducing more tofu and soy milk ( among other soy products) in place of animal alternatives is a very practical step that the average person can take on a daily basis to improve their health in the long-term.

Don’t sweat it if you truly don’t like soy, or can’t consume it due to allergies,  because there are PLENTY of other plant-based choices out there.

If you need a professionals help to figure all that stuff out, don’t hesitate to reach out.

Until next time,

Andy De Santis RD MPH

Want More Soy Content? Dig In!

Four Good Reasons Why Guys Should Eat More Soy – Andy The RD

Preventing and Managing Gout: Soy Foods May Play a Role – Andy The RD

Does Tofu Lower A Man’s Testosterone Levels?

Soy Intake For Women With PCOS – Hurt Or Help?

Is All Soy GMO And Bad For The Environment?

Soy Intake And Breast Cancer – Hurt Or Help?