The notion that soy intake is unsuitable for males due to its negative interaction with testosterone levels is one of the more problematic modern nutrition beliefs.
Although I’ve discussed the interaction with soy and health outcomes in a number of articles over the last several years, I’ve never written specifically to discuss this topic as it relates to the male gender and testosterone levels.
In today’s article, I turn to the best available evidence of the last decade or so in order to try to determine, once and for all, whether or not soy intake is detrimental to a man’s testosterone levels.
Why Soy Worried?
Testosterone is the primary male sex hormone and so it should come as no surprise that the thought of consuming a food that may explicitly reduce its bioavailabilty would be quite frightening.
This premise is based on the oversimplified notion that soy, which contains compounds that very weakly mimic the female hormone estrogen, will somehow wreak havoc on a male’s endocrine system.
But is there any factual basis for this claim?
Let’s find out!
Soy & Testosterone
I will start by saying, once again, that I fully sympathize with men who omit soy over a belief that it will lower their testosterone levels.
I say this only because it is a truly startling thing to hear, and so you have my sympathy.
It goes without saying that testosterone plays a massive role in sexual functioning and low testosterone levels can be the cause of a decrease in sexual performance.
And while testosterone’s role in male physiology cannot be questioned, soy’s interaction with it certainly can be.
Further to that point, a recently published 2018 paper out of the Scientific Reports journal looking at male college students taking a soy protein supplement found that it had no measurable estrogenic or androgenic affect.
In other words, based on the outcomes measured, there was no evidence soy protein intake altered hormone signalling in this population.
Soy Helps Rather Than Hurts
Given the absence of any explicit high quality evidence suggesting a detrimental effect of soy on male hormones, it’s only reasonable we also explore the other side – is there any potential benefit men may garner from soy intake?
Let’s operate under the assumption that men care about testosterone for concerns surrounding either musculature or sexual performance ( even though, yes, it has tons of other physiological roles).
The first point to clarify is that soy is considered a complete protein that is generally recognized as either very close to or on par in terms of comparisons to animal protein as it relate to biological value and utility.
The second and perhaps more important points relate to sexual and overall health.
Erectile dysfunction may be caused by a number of psychological, pharmacological or physiological impediments, not least of which is poor cardiovascular health since the adequate and effective pumping of blood to the penis is very important for proper sexual function.
Now it’s generally well established that red and processed meats tend to be unfavourable to cardiovascular health, which is why it comes as no surprise that a Mediterranean diet pattern [ which limits the intake of animal-based protein in favour of plant-based protein sources, such as tofu] is associated with a lessening of erectile dysfunction.
This is primarily due to the joint direct + indirect effects of soy intake on cholesterol lowering
Which is why my latest cholesterol lowering cook book, pictured below with a pre-order hyperlink, includes a number of soy-based recipes.
Finally, and further to that point, a 2009 American Journal Of Clinical Nutrition study found soy intake to be protective against prostate cancer, which is the most common male cancer and also a leading contributor to erectile dysfunction.
Final Thoughts + Good News
Hopefully you guys can appreciate the creative direction I went with today’s article given the evidence available to me.
To all the men out there who are scared or apprehensive about consuming tofu, no one is asking you to go vegan or eat it every single day.
It’s a useful tool in your dietary belt and one that is helpful both economically and physiologically.
Andy De Santis RD MPH