Is l-arginine (amino acid) effective for increasing testosterone levels?

L-Arginine for Testosterone Enhancement

L-arginine supplementation is not effective for increasing testosterone levels based on current evidence. 1

Evidence on L-Arginine and Testosterone

• L-arginine is an amino acid that serves as a substrate for nitric oxide production, which plays roles in vascular function and glucose homeostasis 2, 3
• While some animal studies suggest potential benefits, human clinical evidence does not support L-arginine supplementation for testosterone enhancement 1
• A scoping review of nonpharmacological interventions found only modest effects of L-arginine on testosterone levels that do not directly translate into clinical benefits 1

Animal Studies vs. Human Evidence

• In animal models, L-arginine has shown some positive effects:

  • L-arginine ameliorated testosterone levels decreased by T-2 toxin in mouse Leydig cells by regulating steroidogenic enzymes 4
  • Intramuscular L-arginine administration in heat-stressed rams increased plasma testosterone concentrations and improved testicular blood flow 5

• However, human studies show different results:

  • Oral L-arginine supplementation (both low and high doses) failed to produce significant hormonal responses in young active males 6
  • While hypogonadal patients may have altered L-arginine metabolism, supplementation has not been proven to increase testosterone in healthy individuals 7

Clinical Applications of L-Arginine

• L-arginine has been studied for other clinical applications with variable results:
  • For peripheral artery disease: The effectiveness of L-arginine for patients with intermittent claudication is not well established (Level of Evidence: B) 2
  • For sepsis and septic shock: Guidelines suggest against the use of arginine (weak recommendation, low quality of evidence) 2
  • For neonatal conditions: Conditional recommendations exist for arginine supplementation in preventing necrotizing enterocolitis in preterm infants 8, 9, 3

Potential Risks and Considerations

• L-arginine supplementation could potentially lead to unwanted vasodilation and hypotension in certain patients 2
• Studies in septic patients have shown variable effects on mortality with some suggesting possible harm 2
• The American College of Physicians provides no recommendations regarding L-arginine for testosterone enhancement in their guidelines on testosterone treatment in adult men 2

Bottom Line

• Current evidence does not support L-arginine supplementation as an effective strategy for increasing testosterone levels in healthy adults 1
• If addressing low testosterone is the clinical goal, established pharmacological approaches or other lifestyle modifications (adequate sleep, exercise, weight loss) should be considered before supplements 1
• For those still interested in nutritional approaches, other supplements like zinc, vitamin D (in cases of deficiency), and ashwagandha have shown more promising results in clinical trials 1