Last Updated on May 19, 2021 by Mark McIntyre
It’s no secret that testosterone is an important male hormone responsible for building muscle, sex drive and male characteristics.
Whether due to low testosterone as a result of aging (andropause), or a desire to enhance bodybuilding or athletic performance, the demand for naturally being able to increase this hormone is great.
The most popular way of doing this is by taking testosterone-boosting supplements. One ingredient that you may notice being added to many of these products is D-aspartic acid.
Get ready, because today you’re going to learn what D-aspartic is, and whether or not it can actually increase testosterone levels.
What Is D-Aspartic Acid?
D-aspartic acid (or DAA) is an amino acid responsible for producing and secreting hormones in the body. In case you weren’t paying attention in middle-school science class, amino acids are molecules known as the “building blocks of protein”, not to mention various hormones and neurotransmitters.
Aspartic acid (like most amino acids) comes in two forms; in this case, L-aspartic acid and D-aspartic acid. Although they’re the same chemically, their molecules are arranged as mirror opposites.
While L-aspartic acid is manufactured naturally in the body to create proteins, and the function of D-aspartic acid is to assist in producing and secreting hormones within the body.
D-aspartic acid is able to increase the production of a testosterone precursor within the brain that ultimately leads to the production of testosterone.
DAA is also contributes to the increase of testosterone manufacture and secretion in the testicles.
Because of this, D-aspartic acid is found in numerous supplements aimed at boosting testosterone.
D-Aspartic Acid Supplementation and Testosterone
Clinical studies examining the effect of D-aspartic acid supplementation has on testosterone has returned varied results. Some research has indicated that D-aspartic acid can raise testosterone levels, but other research has not.
A study involving men between the ages of 27 and 37 looked at the results of D-aspartic acid supplementation over a twelve day period.
Among the 23 men who took D-aspartic acid, 20 of them revealed an average 42% increase in testosterone levels at the study’s conclusion.
Even after no longer supplementing with DAA, their testosterone levels remained an average 22% higher three days later, compared to the start of the study.
A separate study conducted over a 28-day period among men taking D-apartic acid who were overweight and obese saw mixed results. A portion of the participants showed no testosterone increase, but those who already had low testosterone levels at the start of the study saw increases of more than 20% .
Still another study looked at the effects of using DAA supplements for more than a one month period. The results showed that men between the ages of 27 and 43 who supplemented with D-aspartic acid for 90 days saw an increase of testosterone of 30–60%.
The participants in these studies were not specifically screened for being physically active. But three additional studies did look at how D-aspartic acid affected men who were considered to be physically active.
One study showed no testosterone increase among young adult men who did weight training and supplemented with D-aspartic acid over a 28 day period.
Further, a different study showed a decrease in testosterone in young men taking large doses of 6 grams daily while weight training.
But no change in testosterone was observed in a follow-up study that used 6 grams daily over a three-month period.
Related studies with women aren’t currently available, possibly due to certain effects of D-aspartic acid being associated with the testicles.
Effect On Workout Gains
Quite a bit of research has studied whether or not D-aspartic acid can improve exercise gains, in particular weight training. It’s commonly believed that it can help boost gains in muscle and strength, primarily because of increased testosterone levels.
Unfortunately, research does not currently show increases in testosterone, muscle mass, or strength among men supplementing with D-aspartic acid while weight training. One research study conducted over a 28-day period showed virtually no difference in muscle mass gains between a group of men taking D-aspartic acid while weight training compared to another group receiving a placebo.
Additionally, the increases in the muscle strength of both groups was comparable. The bottom line is that this study showed that D-aspartic acid did not perform any better than a placebo.
A lengthier study conducted over a three month period also showed that men who worked out saw the same increases in strength and muscle mass, whether or not they were using D-aspartic acid or a placebo.
These two studies each found that D-aspartic acid showed no benefit for boosting strength or muscle mass when used in conjunction with a weight-training routine. However, there isn’t any current research regarding the use of DAA supplementation with other types of exercise, for example running or HIIT (high-intensity interval training).
D-Aspartic Acid and Male Fertility
Even though the amount of research is limited, D-aspartic acid shows potential for helping men dealing with infertility. A study found that D-aspartic acid supplementation over a three month period significantly increased the sperm count among a group of 60 men with fertility problems.
Additionally, sperm motility in these men was improved as well. And these increases in sperm quality and quantity made quite an impact.
The men participating in this study who took D-aspartic acid saw an increase in the pregnancy rate of their partners. More specifically, 27% of the participants’ partners ended up getting pregnant during the study!
Despite the fact that the majority of the research into D-aspartic acid’s effects on fertility has been aimed at men due to its connection to testosterone, it might also have an effect on ovulation in women.
The majority of research looking into the effects that D-aspartic acid has on testosterone levels used between 2.6–3 grams daily. Although there have been conflicting results concerning the effects on testosterone, significant gains were observed in men who were not physically active taking approximately 3 grams daily.
The same amount, however, did not demonstrate effectiveness in young men who were physically active. Two studies using larger dosages of 6 grams daily were also not effective, with one study showing a decrease in testosterone, and the other showing no change.
Research that found D-apartic acid having a positive effect on sperm quality and quantity used 2.6 grams daily over a three month period.
Risks and Potential Side Effects
Researchers looking into the effects of a 2.6 gram daily dose of D-aspartic acid over a 90-day period conducted extensive blood testing to determine whether any negative side effects occurred. The findings indicated no safety issues and concluded that DAA is safe to use for at least a period of 90 days.
However, a different study showed that 2 out of 10 men supplementing with D-aspartic acid experienced headaches, irritability, and anxiety. That said, one participant in the placebo group also noted the same negative effects.
Further research is needed to verify the safety of D-aspartic acid supplementation since the majority of the studies did not note whether or not there were side effects.
A large number of men are looking for a natural methods for increasing testosterone. Studies have shown that D-aspartic acid taken in daily doses of 3 grams can raise testosterone levels in men.
Even so, other studies involving men who are physically active did not demonstrate a boost in testosterone levels, strength, or muscle mass. Some evidence indicates that D-aspartic acid can improve sperm quality and quantity in men having issues with fertility.
Although it appears to be safe to use for at least a 90-day period, there is still a limited amount of information regarding DAA’s safety. Further studies will indicate how effective D-aspartic acid is for increasing testosterone, and in what applications it works best.
Mark McIntyre is the founder of MaleHealthReview.com and acts as it’s chief contributor. He is a fitness trainer and avid mountain biker who also enjoys camping, hiking and fishing. Besides managing Male Health Review, Mark is also a guest columnist for several blogs related to men’s health. More about this author…