Many of my readers are familiar with my research on herbal remedies–trying to find the science behind the fads. But there’s also good science to uncover regarding everyday vitamins and minerals. In this article, I’ll be diving into an amino acid called L-Arginine (or just Arginine).
Commonly found in meat, dairy, eggs, nuts, and certain grains, it is an absolutely essential amino acid for animals who rely on a mainly meat diet. For humans, it is called semi-essential, because our metabolisms are able to break down and reform amino acids better than most animals. Here, our focus will be on whether it can, or cannot, actually boost testosterone.
Key Findings
✲ Animal studies have extensively shown a positive correlation between Arginine and Testosterone–especially in males.
✲ Human studies, while more limited, have been promising, especially when Arginine is combined with dietary or exercise changes.
✲ One study showed symptomatic improvements, but no testosterone gains.
✲ More of the mechanism needs to be studied for any conclusive analysis.
Animal Studies
One of the oldest (but still scientifically valid) studies on Arginine was published in the Journal of Endocrinology, and performed exhaustive experimentation on male and female rats using Arginine as the variable. They examined both restricting and supplementing Arginine; they measured body weight and muscle mass; had meticulous controls on food and activity; and even performed chemical analysis of kidney functions to determine Arginine reactions in the body.
Their conclusions were fairly straightforward: Arginine has a direct impact on testosterone in males. This study has led to literally dozens of other studies, with scientists testing everything from Arginine’s ability to protect sperm production in extreme heat among boars and mice to whether Arginine can keep Leydig cells protected after being poisoned (Leydig cells produce testosterone in the testes, and yes this was an animal study, thankfully).
Lastly, we have weight-training rats (you read that correctly) who were put through their paces with and without Arginine supplementation, and those with the amino acid, again, had significant testosterone gains.
All of the studies show a positive correlation to testes, Leydig, and testosterone health with Arginine intake–the more of the amino acid, the better the outcomes.
Human Studies
Again, thankfully the human studies haven’t involved any mistreatment of subjects. The first study to consider is one in which three variable groups were assessed next to a fourth placebo group. The three test groups were Arginine alone; tadalafil (generic Cialis) alone; and Arginine and tadalafil together. I regularly stay away from studies with mixed medications, but this was published in a well-respected journal, and has since been cited by other researchers multiple times.
In their data, they found that while tadalafil and Arginine alone worked for ED, when combined there was a significant testosterone increase compared to all three other groups.
Conversely, a long-term, high-dose study of Arginine alone found all indices of sexual health improved–including testosterone increases–but not to a significant level.
A Blast from the Past
Without citing textbooks–incredibly useless if my readers don’t have the same bookshelf as I do–I often have trouble showing direct links that are long-established science. In this case, I was able to track down a reference from a study carried out over 60 years ago–a simple but groundbreaking laboratory experiment.
In it, scientists were first starting to sort out what exactly amino acids did, and they found that for six acids in the L- group (including Arginine), testosterone was more soluble (bioavailable) at higher ionic strengths. For what it may be worth to the reader, studies aside, it is long-established that there is a role that Arginine plays with testosterone–it only remains in future studies to determine to what extent.
Conclusion
It’s difficult to isolate the effect of Arginine with certain body chemistries, in large part because it is such a prevalent amino acid that it can be almost impossible to assess supplementation with it. After all, with animals, researchers can take the Arginine completely out of their diet, and control how much the animal gets over the course of a study.
But with humans, we cannot simply tell a person not to eat X, Y, or Z and still keep the study properly blinded or controlled. For that reason, and many others, we may have to keep researching the role of Arginine and testosterone production in animal studies. Those studies, however, do have compelling correlations to the positive effect of Arginine on the production of testosterone.