D-Aspartic Acid: Usage, Health Benefits & Side Effects

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For years and years, human beings have been looking for ways to optimize their athletic performance and abilities.

Nowadays, many turn to supplements. While it is clear that there are some highly effective supplements, there are other products that have little to no impact.

This article will review the science behind D-aspartic acid. This nutritional supplement is commonly used in an attempt to increase testosterone levels and enhance nervous system function.

What is D-Aspartic Acid?

Aspartic acid, sometimes known as aspartate, is a type of amino acid. Amino acids are the building blocks that make up proteins.

A number of amino acids cannot be synthesized by the body and must be consumed through food. However, aspartic acid is a naturally occurring acid that can be synthesized.

This acid is commonly found in protein-rich foods such as chicken, eggs, beef, fish, and dairy. A number of popular nutritional supplements also contain aspartic acid.

Aspartic acid exists in two different forms – L and D-aspartic acid. L-aspartic acid is used to build proteins while D-aspartic acid plays a key role in the neuroendocrine system.

Neuroendocrine is the system responsible for controlling a number of vital bodily functions. Hormones, metabolism, reproduction, sleep, and energy are all managed by this system.

D-aspartic acid has been linked with reducing tiredness, improving performance, and enhancing muscle strength and size.

How Does It Work?

D-aspartic acid can be found within the nervous and endocrine systems of the body. Its role has been studied in detail over the years.

One of its main functions is to produce hormones that regulate a multitude of bodily functions. It also appears to influence the development and growth of nerve cells. (1)

Therefore, it is theorized that increasing D-aspartic acid consumption can optimize hormone production and nervous system function.

Enhancing both of these elements may bring about a range of physiological changes and improvements.

Is It Safe?

Most amino acid supplements are safe to take providing that the recommended dose is adhered to. (2)

One specific study investigated the effects of D-aspartic acid over a 90 day period. Blood tests were determined that the substance was safe to use with no side effects noted (3).

However, animal studies have indicated a potential link between d-aspartic acid intake and brain dysfunction.

The study showed that a high concentration of aspartic acid caused cognitive dysfunction in rats. While the link is tenuous, more research is required to determine the effect on humans. (4)

D-Aspartic Acid Health Benefits

D-Aspartic Acid Benefits

There are a variety of potential benefits associated with increasing d-aspartic acid intake.

1. Boosts Testosterone Levels

What the Science Says

Although a great quantity of research has been performed on rats, studies on human supplementation are limited.

However, one human study found that, after twelve days, D-aspartic acid supplementation caused a 42% increase in testosterone. (5)

On the other hand, results from another study indicated that supplementation had an insignificant effect on testosterone levels (6).

Conflicting research makes it extremely challenging to determine whether or not testosterone levels can be enhanced through D-aspartic acid supplements.

2. Increases Muscle Strength and Size

What the Science Says

Testosterone is the main driver of muscle growth (7). It is theorized that taking D-aspartic acid causes testosterone levels to increase thus enhancing muscle strength and size.

Research has consequently focused on whether D-aspartic acid alters the response to exercise.

The results appear to indicate that D-aspartic acid supplementation is ineffective for improving muscle strength and size. (8)

Considering there are only a handful of studies available on the subject, it would be improper to categorically confirm this. Additional research is necessary.

3. Promotes Fat Loss

What the Science Says

In addition to promoting muscle gain, testosterone has an influence on fat mass. It is well-documented that testosterone therapy can lead to a decrease in visceral fat. (9)

Therefore, in a similar way to muscle growth, D-aspartic acid supplements may lead to fat loss by increasing testosterone levels.

The same study that investigated the impact of supplementation of muscle size and strength also assessed fat mass. (8)

When compared to a placebo, results showed that fat mass was not affected by 28 days of D-aspartic acid supplementation. More research into the impact on fat mass is required.

4. Improves Fertility

What the Science Says

Another common proposed benefit of D-aspartic acid supplementation is greater fertility. By boosting testosterone levels, it is hypothesized that sperm quality will improve.

Results from certain studies have shown promise for those who are experiencing infertility.

One particular study investigated supplementation and sperm production and quality. After three months of supplementation, a significant increase in sperm count was noted. (3)

However, once again, there is a lack of concrete evidence and other studies have found supplementation to be ineffectual.

5. Improves Cognitive Abilities

What the Science Says

Considering the role that D-aspartic acid plays in the nervous system, it has been suggested that supplementation can enhance cognitive function.

Several studies exist that suggest that the acid works by enhancing nerve signals and regulating the actions of neurons.

Consequently, the belief is that D-aspartic acid can improve specific cognitive abilities such as learning and memory (10).

Nevertheless, these findings should be treated with caution as the studies were performed on rats. Therefore, the effects displayed in the rats may not be replicated in humans.

Side Effects

While D-aspartic acid does appear to be safe, there have been some reported side effects. More research is needed to confirm the risk of experiencing the following side effects.

  • Brain Dysfunction
  • Irritability
  • Headaches
  • Nervousness

Usage and Dosing Considerations

If supplementing D-aspartic acid, it is critical that a high-quality product is used. Not only will this be more effective than poorly manufactured supplements, but it will also be safer.

For optimal impact, the recommended dosage tends to around three to six grams. However, most products will provide recommended dosages.

It is vital that we do not exceed these dosages. Failure to adhere to the recommendations may increase the risk of experiencing side effects.

As with all supplements, it is important to speak to a qualified medical professional before taking a D-aspartic acid supplement.


What is the difference between L-aspartic acid and D-aspartic acid?

There are two types of aspartic acid – L and D. Both are non-essential amino acids which means that the body can synthesize these substances itself.

L-aspartic acid is directly incorporated into protein molecules and also plays a role in energy production.

Meanwhile, D-aspartic acid is used in the neuroendocrine system. It plays a key role in regulating physiological functions such as hormone production.

Does D-aspartic acid increase testosterone production?

Research is mixed. Some studies suggest that increasing D-aspartic acid intake increases testosterone production while others have found it to have little impact.

Ultimately, more research is required to ascertain the impact that increasing D-aspartic acid has on hormone production.

What foods are high in D-aspartic acid?

The majority of protein-rich foods contain a large quantity of D-aspartic acid.

Examples of foods high in D-aspartic acid:

  • Beef
  • Chicken
  • Dairy
  • Eggs
  • Lamb
  • Pork
  • Seafood
  • Soy
  • Turkey

Should we be taking D-aspartic acid as a supplement?

Whether or not D-aspartic acid is taken is determined by personal preference. Research is currently inconclusive, however, benefits may well be experienced through supplementation.

Providing that recommended dose is adhered to, supplementing D-aspartic acid does appear to be safe.

How long does it take for D-aspartic acid to work?

Studies looking into supplementation have indicated that it may take 7-14 days for changes to take place.

However, there are a number of factors including physical characteristics, dosage, exercise, and nutrition that can influence changes.

How long should D-aspartic acid be taken for?

As highlighted, one specific study had participants use D-aspartic acid for 90 consecutive days. The blood work indicated no adverse reactions throughout the 90 days. (3)

With that being said, always check the manufacturer’s guidelines. Often, the product will specify the maximal time that the supplement can be taken for.


While D-aspartic acid shows promise, the lack of research into the substance clouds the waters.

The results from testosterone production and fertility studies are particularly promising. However, evidence of positive changes in body composition and cognition is lacking.

One of the major issues with the research is that it has mostly been conducted on animals rather than humans.

It is abundantly clear that many more human studies are required to determine the potential benefits of D-aspartic acid supplementation.

While there are question marks surrounding effectiveness, it appears that D-aspartic acid supplements are safe. With that being said, it is vital to consult a physician prior to taking it.



  1. https://www.ncbi.nlm.nih.gov/pubmed/17118457
  2. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2129148/
  3. https://www.scirp.org/journal/PaperInformation.aspx?paperID=24016
  4. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4146156/
  5. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2774316/
  6. https://www.ncbi.nlm.nih.gov/pubmed/24074738
  7. https://www.ncbi.nlm.nih.gov/pubmed/15075918
  8. https://www.ncbi.nlm.nih.gov/pubmed/28841667
  9. https://www.ncbi.nlm.nih.gov/pubmed/17164307
  10. https://www.ncbi.nlm.nih.gov/pubmed/19890700

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