L-Arginine Benefits for Cardiovascular Health and Exercise Performance
L-arginine supplementation shows promising but limited benefits for cardiovascular health and exercise performance, with insufficient evidence to recommend it as a primary therapy for most cardiovascular conditions. 1, 2
Cardiovascular Health Benefits
Mechanism of Action
- L-arginine is the precursor for nitric oxide (NO) synthesis in the endothelium
- NO induces vasodilation and inhibits platelet aggregation by activating guanylyl cyclase and increasing cyclic guanosine monophosphate 1
- Endothelium-dependent vasodilation mediated by NO is impaired in patients with atherosclerosis and PAD 1
Evidence for Cardiovascular Benefits
Peripheral Arterial Disease (PAD)
- In PAD patients with intermittent claudication:
- Intravenous L-arginine (8g twice daily) improved pain-free and maximal walking distance after 3 weeks 1
- A food bar containing 3.3g L-arginine showed modest improvement in walking distance after 2 weeks 1
- However, a larger placebo-controlled trial with L-arginine-enriched food bars showed negative results 1
Pulmonary Arterial Hypertension (PAH)
- Short-term oral supplementation (1.5g/10kg body weight daily for 1 week) in PAH patients:
- Decreased mean pulmonary arterial pressure by 9%
- Decreased pulmonary vascular resistance by 16%
- Slightly increased peak oxygen uptake
- Decreased ventilatory response to carbon dioxide production 1
Limitations for Cardiovascular Use
- Effects appear modest and primarily short-term
- Potential drawbacks include increased concentration of polyamines (which are proproliferative) 1
- ACC/AHA guidelines state it is premature to recommend L-arginine for treatment of intermittent claudication 1, 2
- Long-term randomized trials are lacking 1
Exercise Performance Benefits
- Evidence for exercise performance enhancement is mixed and limited 3
- Potential benefits include:
Safety Profile
- Low oral doses (≤20g) are generally well tolerated 3
- Clinical side effects are rare in healthy subjects 3
- May cause modest decreases in systemic blood pressure 1
Current Recommendations
For Cardiovascular Conditions
- Not currently recommended as primary therapy for PAD or intermittent claudication 1, 2
- The American College of Cardiology lists L-arginine as having unestablished effectiveness (Class IIb) for intermittent claudication treatment 2
- May be considered as an adjunctive therapy in specific conditions like PAH, but requires further study 1
For Exercise Performance
- Still premature to recommend as an ergogenic aid for healthy physically active subjects 3
- May have more benefit in populations with underlying vascular dysfunction (e.g., diabetes) 4
Clinical Applications
When to Consider L-arginine
- As adjunctive therapy in patients with endothelial dysfunction
- In patients with uncomplicated type 1 diabetes to improve vascular function 4
- For mild erectile dysfunction as an alternative to PDE5 inhibitors 5
When Not to Use
- As primary therapy for PAD or intermittent claudication
- As a replacement for established treatments like supervised exercise programs or pharmacological options (cilostazol) for PAD 2
Dosing Considerations
- Cardiovascular studies: 3.3-8g daily (divided doses)
- Exercise performance: typically 7g daily
- FDA-approved indications: temporary relief of minor muscle pain, inflammation, fatigue, and diminished sexual performance 6