This question comes up every now and then — does soy lower testosterone?
The short answer is probably not, but let’s talk about why this is even a question in the first place.
Soy contains a compounds called phytoestrogens (they’re also called isoflavones), a nutrient found in plants that is similar in structure to one of your body’s endogenous (naturally produced) hormones: estrogen.
You can probably already see where the original question came from.
If you’re adding estrogen-like nutrients into your body, you might start to wonder how those nutrients are interacting with your naturally produced hormones — especially your testosterone.
Fortunately, several studies suggest that phytoestrogens have a minimal effect on your testosterone levels. Further, some evidence suggests that soy is a bit healthier than your average food, meaning you might want to eat more soy, rather than less.
Let’s Dig in a Little Deeper. Does Soy Lower Testosterone? Unlikely. And Here’s Why
Your intestines get in the way.
There are a variety of isoflavones in soy, but several of the main ones are biologically inactive until they hit your intestinal tract (specifically, these compounds are activated by your intestinal bacteria).
This study suggests that your intestines are playing a sort of inhibitory role, keeping your body from using many of these phytoestrogens.
So eating a large amount of soy isn’t like injecting estrogen into your body. Your digestive system mitigates the effects that these compounds may or may not have on your hormone levels.
Finally, it’s important to keep in mind that these compounds are not identical to your hormones, just chemically similar. It’s not the same as getting bioidentical estrogen from your medical provider.
The Final Analysis — Little Evidence to Show Soy Reduces Testosterone
Even taking all this information into account, many studies still exist that seem to be conflicting.
On top of this, you’ll see lots of anecdotal evidence from individuals mixed with misinformation and misunderstanding to end up with a muddied picture of the real effects (or lack thereof) of soy.
That’s why, about six years ago, a few researchers performed a meta-analysis of existing studies on isoflavones. They looked at all the studies out there on soy, phytoestrogens, and isoflavones to see whether they had any effect on testosterone levels.
So, does soy lower testosterone?
Here’s the results:
Eating soy (or any sort of isoflavone supplement) has no measurable effect on free testosterone levels.
Soy Probably Won’t Hurt Your Testosterone — But It May Help You Become Healthier
I want to start by saying this: Soy is not a superfood, and it’s not going to change your health on its own. You need diet and exercise as well as properly functioning hormones to really see a change in your body.
That being said, soy does appear to benefit your cardiovascular health because of the other nutrients it contains, like fiber, polyunsaturated fats, and other vitamins and minerals.
While the phytoestrogens (isoflavones) likely play a small role in the overall healthiness of soy, they probably don’t have much benefit (or do much damage) on their own.
The truth is this — soy isn’t a superfood, but it’s certainly healthier than many other foods. So, does soy lower testosterone? No — and it may actually benefit you.
In fact, if you replace something unhealthy in your diet with soy beans, you might find a lot more benefit than simply adding soy to your diet. For instance, replacing an afternoon snack of potato chips with edamame is a simple, small step you can take towards a healthier diet.
Don’t Worry About Soy — Instead, Look at Your Symptoms and See a Medical Provider
So, does soy lower testosterone? It’s doubtful — and adding soy to your diet likely has health benefits that far outweigh this tiny risk.
At the end of the day, if you have low testosterone, truly low testosterone (not testosterone that’s on the borderline), diet and exercise aren’t going to make much difference.
If your testosterone is low because of a problem in your body, testosterone replacement therapy is likely necessary.
But how do you know if your testosterone is low? First, start by examining your symptoms.
Click the button to take the Low T Symptoms Quiz.