After working with spermidine long enough to know its levels in wheat germ, broccoli, and aged cheese by heart, I have a confession: I never actually knew how much spermidine was in sperm. A bit ironic, don’t you think? Especially considering that’s where spermidine got its name in the first place.
Back in the 1670s, the legendary Antonie van Leeuwenhoek (aka the inventor of the microscope and certified curious human) first discovered crystalline structures in semen, which turned out to be spermine and spermidine, which we now know are two naturally occurring polyamines essential for proper cellular function. Now, I like to imagine he was left alone in a room with his microscope for way too long, and… well, the rest is scientific history. Is that how it really happened? Who knows. But it’s a great story.
So we know there was enough spermidine in semen to crystallize. But how much, exactly? Enough to bottle up and sell as a supplement? Let's dive in.
Comparative spermidine content (mg/g) in spermidineLIFE®, common foods, and semen. Value for semen was calculated from Table 1 and using semen density value from Matson et al. (2010). Food values were obtained from Atiya Ali et al. (2011). © 2025 Melissa Cano. All rights reserved.
Why is there a significant amount of spermidine in semen?
I’ve been asked this more times than I can count—by doctors, researchers, and curious minds of all ages. My usual response? “Yes, there is spermidine in sperm, but not enough to replace your daily supplement.” Turns out I was right… and now I’ve got the numbers to back it up.
Before diving into the specifics, it’s important to clarify a few terms: semen consists of two main components: sperm (the reproductive cells or spermatozoa) and seminal plasma or fluid (the liquid that carries them). In a given volume of semen, most polyamines—including spermidine—are located in the seminal plasma rather than within the sperm cells themselves (as shown in Table S2 of Engel et al.). Therefore, the concentration of spermidine in the seminal plasma effectively represents the total spermidine content of semen. For this reason, we will focus on spermidine levels in the seminal plasma, as they serve as a reliable indicator of its overall amount in semen.
Semen contains a (relatively) high concentration of spermidine (and other polyamines) because it's rich in germline cells and designed to support reproduction at the cellular level. Interestingly, this same abundance is seen in embryonic tissues, including plant embryos like wheat germ. Why? Because these cells are life’s launchpads, and spermidine helps fuel that launch.
Spermidine supports reproductive process and cellular development by:
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Enhancing DNA and RNA synthesis
Germline and embryonic cells undergo rapid division and require substantial amounts of DNA and RNA. Spermidine binds to negatively charged nucleic acids, stabilizing their structure and supporting both replication and transcription. This makes it essential for proper cell cycle progression. -
Meeting high metabolic demands
These cells exhibit intense biosynthetic activity, producing proteins, building organelles, and preparing for growth. Polyamines such as spermidine support ribosome function, mRNA translation, and enzyme activity, all of which are highly active in early-stage cells. -
Promoting stress protection and autophagy
Spermidine induces autophagy, the cell’s mechanism for clearing damaged components, which is critical for quality control during rapid development. It also acts as an antioxidant, protecting cellular structures from oxidative stress. -
Supporting epigenetic reprogramming
During gametogenesis and embryogenesis, cells undergo extensive epigenetic remodeling. Spermidine plays a role in regulating histone acetylation and chromatin structure, guiding the gene expression patterns required for proper development.
Spermidine concentration in semen: understanding the numbers and comparing to supplementation
Let’s not wait any longer and go to the point.
🧪 Spermidine concentration in seminal fluid:
The reported concentration in the literature varies widely, typically ranging from 50–250 µM (about 7–22 mg/L, or 0.007–0.022 mg/mL). These values depend on factors like age, health, and the measurement methods used, but that’s the general ballpark.
🧴 Average semen volume:
In a study of 60,823 individuals, the mean ejaculated seminal volume was found to be 3.4 mL. Multiply that by the spermidine concentration, and you get 0.025–0.075 mg of spermidine per sample.
💊 For comparison:
A single dose of spermidineLIFE contains several milligrams of spermidine, about 100 times more than what’s found in an average semen sample.
Table 1 below presents a comparative summary of average spermidine concentrations in seminal plasma, as reported across three independent studies. I have also included a bar graph that compares the amount of spermidine (in mg/g) found in semen with that in foods rich in spermidine, as well as in spermidineLIFE supplements at the top of this article. This should provide a clear perspective on just how small the amount of spermidine is in sperm.
Table 1. Spermidine levels in semen and their equivalent spermidineLIFE daily dose. Values of spermidine content in seminal plasma were obtained from Oefner et al. (1992), Vanella et al. (1978) and Engel et al. (2019). Spermidine content in ejaculated seminal volume in mg/g was calculated using semen density value obtained from Matson et al. (2010). © 2025 Melissa Cano. All rights reserved.
So… is semen a good source of spermidine supplementation?
NO. To match what you would get from a supplement, you would need... well, a lot of seminal fluid, which is definitely not a practical source for spermidine 😅. Stick to good foods and our supplement. There you have it. You’re officially spermidine trivia-ready for your next awkward dinner party or scientific conference icebreaker. You’re welcome.
