Supplement

D-Aspartic Acid

D-aspartic acid is an amino acid that may prompt the release of luteinizing hormone, a signal that tells the testes to make testosterone. People mostly look at it for low testosterone, but the evidence there is limited, drawing on about 250 participants in total. Research in 20 people also found no clear difference in body fat or estrogen, so the research is thin overall.

Updated 30 September 2026
How we grade
2 studies cited

Best evidence: Grade D
Conditions studied: 6
Outcomes: 31
Graded outcomes: 0006

Evidence by condition

Strong
Moderate
Limited
Very limited

6 conditions

Metabolic Health

Metabolic Health: outcomes studied for D-Aspartic Acid
Grade	Outcome	Effect	Size	Studies	People
	Body Fat No effect		NoneNo effect		20 people
	Estrogen No effect		NoneNo effect		20 people
	Testosterone	Improves (the measure goes up)		2 studies	44 people
Studies that measured testosterone Three and six grams supplementation of d-aspartic acid in resistance trained menJ Int Soc Sports Nutr · 2013 · PMID 25844073 The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and ratsReprod Biol Endocrinol · PMID 19860889
	Free Testosterone	Improves (the measure goes up)			24 people
	Muscle Mass	Improves (the measure goes up)			20 people
	Weight	Improves (the measure goes down)			20 people

Body Composition

Body Composition: outcomes studied for D-Aspartic Acid
Grade	Outcome	Effect	Size	Studies	People
	Body Fat No effect		NoneNo effect		20 people
	Testosterone	Improves (the measure goes up)		2 studies	20 people
Studies that measured testosterone Three and six grams supplementation of d-aspartic acid in resistance trained menJ Int Soc Sports Nutr · 2013 · PMID 25844073 The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and ratsReprod Biol Endocrinol · PMID 19860889
	Estrogen	Changes; see studies			20 people
	Muscle Mass	Improves (the measure goes up)			20 people
	Power Output	Improves (the measure goes up)			20 people
	Weight	Improves (the measure goes down)			20 people

Muscle Size Strength

Body Fat
Testosterone: improves
Estrogen: changes; see studies

Muscle Size Strength: outcomes studied for D-Aspartic Acid
Grade	Outcome	Effect	Size	Studies	People
	Body Fat No effect		NoneNo effect		20 people
	Testosterone	Improves (the measure goes up)		2 studies	20 people
Studies that measured testosterone Three and six grams supplementation of d-aspartic acid in resistance trained menJ Int Soc Sports Nutr · 2013 · PMID 25844073 The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and ratsReprod Biol Endocrinol · PMID 19860889
	Estrogen	Changes; see studies			20 people
	Muscle Mass	Improves (the measure goes up)			20 people
	Power Output	Improves (the measure goes up)			20 people
	Weight	Improves (the measure goes down)			20 people

General Athletic Performance

Body Fat
Testosterone: improves
Estrogen: changes; see studies

General Athletic Performance: outcomes studied for D-Aspartic Acid
Grade	Outcome	Effect	Size	Studies	People
	Body Fat No effect		NoneNo effect		20 people
	Testosterone	Improves (the measure goes up)		2 studies	20 people
Studies that measured testosterone Three and six grams supplementation of d-aspartic acid in resistance trained menJ Int Soc Sports Nutr · 2013 · PMID 25844073 The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and ratsReprod Biol Endocrinol · PMID 19860889
	Estrogen	Changes; see studies			20 people
	Muscle Mass	Improves (the measure goes up)			20 people
	Power Output	Improves (the measure goes up)			20 people
	Weight	Improves (the measure goes down)			20 people

Muscle Size & Strength

Body Fat
Testosterone: improves
Estrogen: changes; see studies

Muscle Size & Strength: outcomes studied for D-Aspartic Acid
Grade	Outcome	Effect	Size	Studies	People
	Body Fat No effect		NoneNo effect		20 people
	Testosterone	Improves (the measure goes up)		2 studies	20 people
Studies that measured testosterone Three and six grams supplementation of d-aspartic acid in resistance trained menJ Int Soc Sports Nutr · 2013 · PMID 25844073 The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and ratsReprod Biol Endocrinol · PMID 19860889
	Estrogen	Changes; see studies			20 people
	Muscle Mass	Improves (the measure goes up)			20 people
	Power Output	Improves (the measure goes up)			20 people
	Weight	Changes; see studies			20 people

Hormone Health

Testosterone: improves

Hormone Health: outcomes studied for D-Aspartic Acid
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Testosterone	Improves (the measure goes up)		2 studies	43 people
Studies that measured testosterone Three and six grams supplementation of d-aspartic acid in resistance trained menJ Int Soc Sports Nutr · 2013 · PMID 25844073 The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and ratsReprod Biol Endocrinol · PMID 19860889

Key findings

Body FatMetabolic Health
EstrogenMetabolic Health

Shop D-Aspartic Acid

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Grade D

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Studies cited

2 studies from PubMed

Three and six grams supplementation of d-aspartic acid in resistance trained menJ Int Soc Sports Nutr, 2013 · PMID 25844073
The role and molecular mechanism of D-aspartic acid in the release and synthesis of LH and testosterone in humans and ratsReprod Biol Endocrinol · PMID 19860889