Arginine is classified as a conditionally essential (or semiessential) amino acid, meaning the body can usually synthesize it—but requirements increase during growth, illness, or physiologic stress. Preterm infants, for example, cannot synthesize adequate arginine, making it nutritionally essential in that setting.
Arginine is also the primary substrate for nitric oxide (NO) production, which plays a key role in vascular tone, blood flow, and endothelial function—mechanisms highly relevant to cardiovascular disease.
Research published in the Journal of the American College of Cardiology (1995 Nov 1;26[5]:1251–1256) examined the effects of intravenous L-arginine in 12 patients with congestive heart failure, classified as New York Heart Association (NYHA) class II or III. L-arginine infusion produced:
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Significant increases in stroke volume
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Increased cardiac output
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Reduced mean arterial pressure
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Reduced systemic vascular resistance
These findings suggest improved cardiac efficiency and peripheral vasodilation.
Similar results were reported in Clinical Cardiology (2000;23:205–210). In this study, L-arginine infusion led to:
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Reduced arterial blood pressure
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Reduced heart rate (from an average of 88 to 80 beats per minute)
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Increased right atrial pressure
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Increased stroke volume and cardiac output
Overall, L-arginine administration was associated with improved hemodynamic performance in patients with heart failure.
