Cognitive performance of 20 healthy humans supplemented with L-homoarginine for 4 weeks

Abstract l -homoarginine ( l -hArg) is an endogenous non-proteinogenic amino acid. Low l -hArg concentrations are associated with increased all-cause mortality, fatal strokes, and worse outcome after stroke. On the other hand, oral supplementation with l -hArg in mice improved neurological deficits and preserved cardiac function in experimental models of stroke and heart failure, respectively. Recently, oral supplementation with 125 mg daily l -hArg capsules in healthy volunteers demonstrated increased l -hArg plasma levels. Therefore, oral l -hArg supplementation could represent a potential treatment for patients with cerebrovascular disease. In addition to vascular physiology, animal studies have suggested that l -hArg might play a role in synapse function, neurotransmitter metabolism and cognitive training. However the direct influence of l -hArg on cognitive function has not been studied so far. In this study, cognitive performance in healthy humans was analyzed concerning memory, learning, and attention following supplementation with placebo or l -hArg for 4 weeks. Our results did not reveal any effects on cognition, neither impairment nor improvement, upon l -hArg supplementation. Therefore, potential l -hArg treatment is not expected to cause any acute neurocognitive or behavioral side effects.