L-Arginine

Your intake

What each level of l-arginine does

Approximate dose-response bands. Individual response varies — these are starting points, not prescriptions.

1. Severely lowYOU ARE HERE

   0 g – 0.99 g

   Well below target. Risk of deficiency symptoms tied to nitric oxide.

2. Insufficient

   0.99 g – 3 g

   Below the recommended daily target. Long-term adequacy not assured.

3. Adequate

   3 g – 4.5 g

   Daily target met. Standard nutritional support for nitric oxide.

4. Therapeutic

   4.5 g – 6 g

   Common for specific health goals. Check the evidence for your situation before sustaining this level.

5. Diminishing returns

   6 g – +

   Past the point where extra intake typically helps. Evidence for further benefit is thin.

Overview

Conditionally essential amino acid, precursor to nitric oxide (NO) via NO synthase, and to creatine, urea, and polyamines. Adequate endogenous synthesis in healthy adults; conditional essentiality in trauma, burns, and certain disease states.

Functions

• ●Substrate for NO synthase → nitric oxide (vasodilation, immune signalling)
• ●Substrate for urea cycle (ammonia detoxification)
• ●Precursor for creatine synthesis (with glycine and methionine)
• ●Precursor for polyamines (cell proliferation)
• ●Substrate for proline → collagen synthesis

Mechanism

Endothelial NO synthase converts L-arginine + O2 to L-citrulline + NO. NO diffuses into vascular smooth muscle, activates guanylate cyclase, raises cGMP, and triggers vasodilation. Pharmacologic effect is limited because arginase competes for arginine; this is why citrulline (which bypasses gut arginase first-pass) often outperforms arginine for NO support.

Benefits

• ●Improves erectile function in mild-to-moderate ED
• ●Improves exercise capacity in heart failure (some trials)
• ●Reduces preeclampsia risk in some pregnancy trials
• ●May accelerate wound healing in surgical and trauma patients
• ●Bodybuilder marketing for 'pump' is weakly supported — citrulline is better

Deficiency

Frank deficiency is rare in adults. Conditional deficiency in trauma, sepsis, burns, and inherited urea cycle defects.

Excess

Well-tolerated to ~9 g/day. GI distress is the typical limit. Post-MI use of high-dose arginine in one trial (VINTAGE-MI) increased mortality — caution in recent CV events.

Forms

• L-arginine HCl
  Standard oral form; affordable; mild stomach upset common at gram doses
• L-arginine alpha-ketoglutarate (AAKG)
  Marketed for bodybuilding; thin evidence vs plain arginine
• Citrulline (precursor)
  Often a better arginine-raising strategy than arginine itself

Food sources

• Pumpkin seeds · 1 oz1.4 g
• Cooked turkey · 3 oz2 g
• Cooked chicken breast · 3 oz1.9 g
• Cooked salmon · 3 oz1.5 g
• Lentils (cooked) · 1 cup1.3 g
• Peanuts · 1 oz0.9 g

Supplement forms

L-arginine HCl or arginine alpha-ketoglutarate at 3–6 g/day. For NO support in healthy adults, citrulline often outperforms arginine on a per-gram basis. Don't combine with PDE-5 inhibitors (Viagra, Cialis) without medical supervision — additive hypotension.

Bioavailability

~70% oral absorption but ~40% is degraded by intestinal arginase before reaching circulation. Citrulline bypasses this first-pass and is converted to arginine renally — a more reliable plasma arginine route at most doses.

Longevity relevance

NO signalling supports endothelial function — vascular health is central to healthspan. Adequate arginine intake from food is typically sufficient; supplementation has small CV benefits in some populations but no clean longevity signal.

Relationships

References

• Examine — Argininereview
• VINTAGE-MI trial — arginine and post-MI mortality (JAMA 2006)study

About L-Arginine

Nitric oxide precursor; vasodilation, blood flow. Common dose 3–6 g/day.

Role

Nitric oxide

Daily target

3 g (TR)

Also called

l-arginine, arginine