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D-Aspartic Acid

D-aspartic acid (D-AA) is an amino acid regulator of testosterone synthesis and may act on a stimulatory receptor (NMDA). D-AA shows promise in aiding male fertility. Healthy men supplementing D-AA experience only temporary increases in testosterone, which limits its use.

Our evidence-based analysis on d-aspartic acid features 54 unique references to scientific papers.

Kamal Patel
Research analysis led by and reviewed by the Examine team.
Last Updated:

Summary of D-Aspartic Acid

Primary information, health benefits, side effects, usage, and other important details

D-aspartic acid is one of two forms of the amino acid aspartic acid. The other form is L-aspartate.

The benefits of D-AA are specific to it, and do not extend to aspartic acid or L-aspartate.

D-AA can be used as a testosterone booster for infertile men, and by athletes as a temporary booster. Elevated testosterone levels only last a week to a week and a half in healthy men, with testosterone returning to normal afterward.

D-AA works in the central brain region to cause a release of hormones, such as luteinizing hormone, follicle-stimulating hormone, and growth hormone. It may also build up in the testicles, where it alleviates a rate-limiting step of testosterone synthesis, which leads to a minor testosterone increase.

Further research is needed on D-AA, as most studies attempt to assess D-AA’s role in the body under normal conditions, and not in the frame of supplementation.

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How to Take

Recommended dosage, active amounts, other details

The standard dose for D-aspartic acid is between 2,000 – 3,000mg.

D-AA is taken daily.

Different studies have used different supplementation protocols. One study used 3,000mg for 12 days, taken daily, followed by a week with no supplementation. A different study did not cycle D-AA, and used 2,000mg of continual daily supplementation with no harm. Further study is needed to determine whether D-AA should be cycled.

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Human Effect Matrix

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The Human Effect Matrix summarizes human studies to tell you what effects D-Aspartic Acid has on your body, how much evidence there is, and how strong these effects are.

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Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
Notes
grade-c
Testosterone

Minor 		- See all 3 studies
There appears to be an increase in testosterone in most subjects acutely (6-12 days), and while this may persist to the tune of 30-60% in infertile men it is reduced to baseline within a month in otherwise healthy men with normal testosterone at baseline. However, high doses also seem to decrease free testosterone and total testosterone in resistance trained men.
grade-c
Body Fat
- - See study
Fat mass does not appear to be altered with D-aspartic acid supplementation alongside exercise.
grade-c
Estrogen
- - See study
Despite a possible induction of aromatase seen in some species, D-aspartic acid supplementation does not appear to increase serum estrogen.
grade-c
Lean Mass
- - See study
No significant influence on lean mass in otherwise healthy trained men.
grade-c
Power Output
- - See study
Otherwise healthy trained men do not experience a further increase in power output relative to placebo when D-aspartic acid is taken alongside resistance training.
grade-c
Weight
- - See study
No significant alterations in body weight when D-aspartic acid is taken alongside resistance training.
grade-d
Fertility
Notable Very High See 2 studies
Limited evidence for D-aspartic acid suggest an increase in fertility of men, with one study noting that a group went from no conceptions to 26.6% of subjects reporting conception over 90 days.
grade-d
Luteinizing Hormone
Minor - See study
An increase in LH concentrations has been noted to 30-60% in infertile men, correlating well with the testosterone increases seen in this study.
grade-d
Seminal Motility
Minor - See study
Seminal motility is increased 50-100% in infertile men supplementing with D-aspartic acid
grade-d
Sperm Count
Minor - See study
Improvements of sperm count in infertile men have been noted to vary between 50-100% increases over baseline.
grade-d
Sperm Quality
Minor - See study
Appears effective, needs to be compared against a comparator.
grade-d
Free Testosterone
- - See study
grade-d
Testosterone (Males)
- - See study

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Things to Note

Is a Form Of

Primary Function:

Other Functions:

Also Known As

D-AA, D-Aspartate, DAA

Do Not Confuse With

DL-Aspartate, Aspartate

  • D-Aspartic Acid may be slightly stimulatory (NMDA receptor)

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This page is regularly updated, to include the most recently available clinical trial evidence.

Each member of our research team is required to have no conflicts of interest, including with supplement manufacturers, food companies, and industry funders. The team includes nutrition researchers, registered dietitians, physicians, and pharmacists. We have a strict editorial process.

This page features 54 references. All factual claims are followed by specifically-applicable references. Click here to see the full set of research information and references for D-Aspartic Acid.

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