Heart/Inflammation

L-Arginine

A nitric oxide precursor amino acid that may modestly improve blood flow, blood pressure, and vascular function in adults.

L-Arginine

A nitric oxide precursor amino acid that may modestly improve blood flow, blood pressure, and vascular function in adults.

score

evidence

Caution

risk

Proven Benefits

01Lowers blood pressure modestly

02Improves endothelial function

03Improves erectile function

04May improve arterial stiffness

05May lower CRP/TNF-α

06May improve walking tolerance

Chemical Forms

Recommended

L-arginine
L-arginine HCl

Avoid

Arginine alpha-ketoglutarate (AAKG) — no proven advantage
Proprietary nitric oxide blends (often underdose actual arginine)

Expert Note

Most human studies use plain L-arginine or L-arginine HCl, which directly provide the amino acid. Popular bodybuilding forms like AAKG have not shown clearly better absorption or clinical outcomes, and proprietary blends often hide how many grams of arginine you are actually getting.

Protocol

Amount

3-6 g

Frequency

Daily, split into 2-3 doses

When

Between meals for absorption, or with food if it causes stomach upset.

Condition-Based Dosing

General vascular support

3-6 g daily in 2-3 divided doses— Most studies use daily dosing for at least 2-8 weeks.

Mild erectile dysfunction

3-5 g daily for 4-8 weeks— Most relevant when blood-flow issues are part of the problem.

Sensitive stomach

1.5-3 g daily to start, then increase as tolerated— GI side effects are the main reason people stop.

Safety & Limits

Upper Safe Limit

No formal UL established; up to 9 g/day has been used in adult trials, but self-use above 6-8 g/day raises GI side-effect risk.

Cycling

Safe for continuous use

Contraindications

Nitrates or nitroglycerin — additive blood-pressure lowering

PDE5 inhibitors such as sildenafil — may further lower blood pressure

Blood pressure medicines — may increase hypotension risk

Recent heart attack — avoid; one trial raised post-MI safety concerns

Recurrent herpes simplex — may trigger outbreaks in susceptible people

Severe kidney disease — impaired amino-acid handling may raise risk

Synergies

L-citrulline

Citrulline is converted to arginine and can sustain plasma arginine longer by bypassing more first-pass metabolism.

Maritime pine bark

Polyphenols may help preserve nitric oxide signaling; combination data for erectile function are stronger than arginine alone.

Avoid Combining With

✕Large protein-heavy meals (take 1-2 hours apart if possible — competes for amino-acid transport)

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