D-Aspartic Acid

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.

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.

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what effects d-aspartic acid has on your body, and how strong these effects are.

Grade	Level of Evidence [show legend]
	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
	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.
	Estrogen	-	- See study	Despite a possible induction of aromatase seen in some species, D-aspartic acid supplementation does not appear to increase serum estrogen.
	Fat Mass	-	- See study	Fat mass does not appear to be altered with D-aspartic acid supplementation alongside exercise.
	Lean Mass	-	- See study	No significant influence on lean mass in otherwise healthy trained men.
	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.
	Weight	-	- See study	No significant alterations in body weight when D-aspartic acid is taken alongside resistance training.
	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.
	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.
	Seminal Motility	Minor	- See study	Seminal motility is increased 50-100% in infertile men supplementing with D-aspartic acid
	Sperm Count	Minor	- See study	Improvements of sperm count in infertile men have been noted to vary between 50-100% increases over baseline.
	Sperm Quality	Minor	- See study	Appears effective, needs to be compared against a comparator.
	Free Testosterone	-	- See study
	Testosterone (Males)	-	- See study

• Aspartic acid on trial: no, it doesn’t boost testosterone

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