Helping Sperm Survive and Thrive
The Microbiome
Your body is only about 9% human. This may come as a shock. Oddly, however, it’s one of those truths you can mostly ignore, like the fact that you’re somewhere between 45% and 75% water. The other stuff—the cells that make up your bones, muscles, connective tissue, membranes, nerves, and organs—are outnumbered about 10-1 by various kinds of microorganisms.
Most of those little guys are bacteria, but some are fungi, viruses, and parasites. Collectively they make up our bodies’ microbiomes, the 10-100 trillion mostly-single-celled organisms that play a huge role in all sorts of bodily functions, especially immune response and digestion/nutrition.
Public discussion of the human microbiome mostly focuses on our guts. You’ve probably heard of fecal matter transplants, aka surgical poop-swapping, which has the highest ratio of how-gross-it-sounds to how-cool-it-actually-is of any known surgical procedure. It can be a brilliant way to fix imbalances in gut bacteria and can help cure various diseases.
Life in Your Balls
The gut microbiome is just the beginning, though. As a group, our microbiota are 150 times as genetically diverse as human beings themselves—humans share about 99.9% of our genes, whereas our bodies’ bacteria might share only 10% or 20% of theirs. Our populations of bacterial freeloaders also change rapidly over time and vary hugely from one part of our bodies to another, and with the biggest influences being diet and antibiotics.
We have microorganisms on our skin and in our hair, racing through our veins and suffusing our saliva. They’re everywhere, and in each place, they have relevant and important effects on our health.
With that in mind, let’s talk testes. The microbiome of human semen is actually more consistent than that of our guts or our skin, but it still has huge variety—including from one part of our reproductive anatomy to another.
In the same way that healthy gut bacteria protect against obesity, there’s some evidence that a healthy diversity of semen microorganisms might protect against prostate cancer.
Semen Microbiota Affect Fertility
They also, according to some very new research, have a major affect on male fertility.
One of the advantages to being born with a penis is that your reproductive anatomy is relatively simple. That doesn’t make infertility any less emotionally crushing for men trying to have kids, but it does make it easier to understand.
Male infertility basically comes down to one of three problems. The simplest is an obstruction that blocks sperm or semen—think vasectomies. Next, sperm might not be produced quickly enough, leading to an absence of sperm in semen. Finally, the sperm might be unhealthy in one way or another, unable to move normally or fertilize an egg.
Your semen microbiome turns out to be strongly connected to problems 2 and 3, respectively called sperm “concentration” and “motility.” The most in-depth study so far found specific species and genera of bacteria that were significantly more common in the semen of men with low sperm concentration, and others that were more common for men with low sperm motility. Another recent study mostly backs up those findings.
The one linked to mobility problems, Lactobacillus iners, is so well-known as a fertility problem in vaginal microbiota that articles about it have titles like “the usual suspect” and “friend or foe?”. The new link to male infertility as well may eventually open up fresh insights or options for treatment.
Cultivating Healthy Ball Bacteria
Unfortunately, we don’t really know how to use this new information productively. There is some research on L. iners that might eventually help us kill it off for the sake of boosting fertility, but frankly, there’s no way to be sure that’d even help. Someday we might have semen transplants, which could help—fecal transplants have already been linked to fertility improvements.
We do have a sense of how to cultivate a healthy microbiome overall:
- Go easy on the antibiotics unless it’s really necessary.
- Consider probiotics, either industrial-strength pharmaceutical ones or everyday alternatives like yogurt, avocados, and sauerkraut. (Actually, anything fermented is great.)
- Fresher food is generally better. Avoid highly processed and ultra-processed foods.
- Avoid artificial sweeteners.
The same goes for a diet that reduces inflammation, as inflammation is likely part of what makes bacteria harmful to sperm. That means avoiding deep fried foods, white flour, excess sugar, red meat, and highly processed food products.
That advice will become more specific as our understanding of this part of human fertility becomes more precise. For now, we think it’s worthwhile to continue to watch this space.
