D-aspartic acid likely ineffective for increasing athletic performance and long-term effects unknown.

D-aspartic acid, or d-aspartate, is one of the first ingredients in most hormone boosting supplements.

That’s because early studies of d-aspartic acid (DAA) show a small increase in testosterone in sedentary and subfertile men. Some studies even show improved athletic performance.

DAA is not approved by the FDA. But one study suggests it’s safe to use for as long as 90 days. Many body-building sites claim that supplementing with DAA is a no-brainer, “natural” way to increase testosterone.

And it is quite possible that for infertile, sedentary men, D-aspartic acid may very well be a safe way to boost testosterone levels.

But as a male athlete, your goal probably isn’t to increase your fertility. And as a female athlete, your goal likely isn’t to mess around with your oocyte production.

You want to be stronger. Faster. Leaner. So the question remains,

Can d-aspartic acid make you a better athlete?


Hormone regulation is a complicated process, so without going into too much detail, all you really need to know is that D-aspartic acid plays a role in testosterone production.

DAA is an amino acid that regulates the hypothalamus-pituitary gonadal axis by increasing plasma testosterone.

DAA is highly concentrated in the pineal gland. (LaMacchia)


D-aspartic acid can be found in various natural sources. Foods containing DAA include:

  • Poultry
  • Beef
  • Pork
  • Dairy and eggs
  • Rice
  • Protein-fortified cereal
  • Some fruits, including bananas and peaches



Athletes take D-aspartic acid to increase testosterone production.

Testosterone increases strength, muscle mass, and physical performance. It can make athletes leaner and can improve muscle size and strength and aerobic endurance. It leads to better recovery and increased power.

Testosterone can even make athletes more competitive and amp up their desire to win. (Vanny, et al.)

There is a reason anabolic steroids are banned in competitive sport: They work.

And early research showed that DAA could increase testosterone production, making it an attractive supplement for athletes.



D-aspartic acid boosts testosterone in some studies.

A 2009 study compared the effects of d-aspartic acid on testosterone levels in men and rats.

  • The experimental group of 23 men ingested d-aspartate for 12 days (while the experimental group of rats ingested d-aspartate for the same amount of time).
  • Researchers found that in both humans and rats, d-aspartate increased testosterone production. (Topo, et al.)

A 2015 study compared the effect of a combination of d-aspartic acid, sodium nitrate, and vitamin D3 on testosterone production in middle-aged, overweight or obese men.

  • Ten participants ingested the supplement for 28 days.
  • Blood testosterone was measured before and after 14 and 28 days.
  • In addition to blood tests, participants also offered a subjective assessment of energy level and libido.
  • The results were all over the place. For most men, each of the three supplements increased testosterone levels at a level of no statistical importance.
  • However, for men with low basal testosterone levels, they experienced an increase of over 20%. (Bloomer, et al.)

Clearly, there is reason to continue research on d-aspartic acid for men with lower-than-normal testosterone levels.

But what about male athletes with normal testosterone production?


There is limited research that suggests that DAA can increase athletic performance.

One randomized, double-blind study in 2016 looked at the effect of d-aspartic acid on athletic performance and testosterone production in young male athletes.

  • The 15 athletes were separated into two groups.
  • Each group either ingested three grams of d-aspartic acid or a placebo for 14 days.
  • Before and after supplementation, athletes completed a physical assessment, which looked at peak VO2, max squat, and max bench press.
  • Researchers found that the DAA group experienced a “positive trend in performance” for the bench press, squat assessment, and VO2 max, yet saw no increase in testosterone production in the experimental group compared to the control. (LaMacchia, et al.)

Despite these findings, further research suggests that athletes may experience an inverse effect from DAA.

A 2015 study from Melville, et al. looked at how DAA may impact testosterone levels in resistance-trained young men.

  • In the abstract, researchers note that previous research suggested that DAA increased testosterone in sedentary and/or infertile men, but showed no increase in testosterone levels in trained athletes.
  • They hypothesized that “a higher doseage may be required for experienced lifters.” So, researchers pumped up the dose.
  • Twenty-four resistance-trained male participants were randomly assigned to three groups: 6 grams daily (gd) plain white flour, 3gd d-aspartic acid, and 6gd of d-aspartic acid.
  • Researchers found the inverse of their hypothesis to be true: athletes who ingested 6gd d-aspartic acid had a decrease in testosterone levels. (Melvillie, et al.)

In a 2017 followup study by Melville, researchers sought to further examine how d-aspartic acid effects athletic performance and testosterone production in trained men, but over a longer period of time.

  • This randomized, double-blind, placebo-controlled trial took place over three months.
  • Twenty-two resistance-trained men, aged 18-36, performed a 12 week, supervised resistance training program supplementing with 6gd DAA.
  • Researchers assessed changes in basal hormones, isometric strength, and cross-sectional muscle thickness of the calves and quadriceps at six weeks and 12 weeks.
  • They concluded that d-aspartic acid led to no change in testosterone production or positive change in training outcomes.

Essentially, they found d-aspartic acid to be safe to supplement up to three months, yet also found it to be ineffectual. (Melville, et al.)


Short answer? We don’t really know.

Some research links d-aspartic acid with female fertility.

One study examined the samples of pre-ovulatory follicle fluid from 20 patients.

  • They tested for concentrations of d-aspartic acid.
  • They found a higher concentration of DAA in younger women aged 22-34 compared to ages 35-40.
  • These results suggest some relationship between fertility and oocyte quality. (D’Aniello, et al.)

But as of today, there aren’t any studies examining the impact of DAA on female athletes, including how it impacts hormonal responses and athletic performance.

That being said, if DAA increases testosterone production in women, it could be a dangerous supplement.

There is a lot of research on the effect of increased testosterone in female athletes.

While DAA research in men is limited with mixed results, DAA research in women is nearly nonexistent. Women should not supplement DAA (or other testosterone boosters).


According to the FDA, no dose of DAA is safe.

Limited studies have been performed on DAA, making it a risky supplement.

Part of the reason manufacturers of supplements containing DAA recommends cycling the product is because its long-term effects are unknown.


Bottom line: don’t take it. Any drug that hasn’t undergone clinical trials or been approved by the FDA probably isn’t worth any potential gains.

DAA could someday be a safe way for infertile men that want to increase testosterone production. It could also be a way to improve sperm quality.

However, that’s about where DAA’s potential ends.

As an athletic enhancer, results are thin and mixed. Some trials suggest an increase in performance, while others show a decrease in natural testosterone production.

When it comes to female athletes, even less is known about DAA.

More broadly, athletes shouldn’t look to increase hormones to gain a competitive edge. Hormone regulation is a complicated system.

To understand the severity of messing with that system, you only need to consider the havoc that anabolic steroids wreak on our bodies.


Athletes who want to try supplements for increased performance should look for safe, effective solutions that don’t mess with fertility and normal hormonal function.

  • For example, good ol’ caffeine is one of the single most effective endurance-enhancing drugs.
  • Beetroot can increase cellular and metabolic efficiency (less oxygen for the same amount of work).
  • Creatine isn’t just for bodybuilders--it’s actually one of the best ways to increase strength, ventilatory threshold, and endurance performance.
  • Taurine reduces muscle breakdown and lactic acid.
  • Beta-alanine increases power output.
  • And that’s really just the start.

With so many safe, effective ways to enhance athletic performance, why would you bother risking your health?


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