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Table 5 Trials testing lysine

From: Nutritional and herbal supplements for anxiety and anxiety-related disorders: systematic review

Reference Study Design Sample Population Intervention Control Length of Treatment Outcomes Direction of Evidence Reported Adverse Events
Jezova (2005) [67] Randomized; Double-blind;
Parallel Group
29 healthy male subjects at the upper limit of the normal range of a trait anxiety scale1 Mixture of L-lysine and L-arginine (3 g each/day) Placebo 10 days AMino acid treatment enhanced adrenocorticotropic hormone, cortisol, adrenaline and noradrenaline levels and galvanic skin responses during stress; no effect on heart rate and blood pressure. + None
Smriga (2007) [68] Randomized; Double-blind;
Parallel Group
108 healthy Japanese adults Oral L-lysine (2.64 g/day) and L-arginine (2.64 g/day) Placebo 1 week L-lysine/L-arginine treatment significantly reduced trait and state anxiety; also decreased basal levels of salivary cortisol and chromogranin-A in male subjects + None
  1. STAI: State Trait Anxiety Inventory.
  2. 1. Scored above 45 on STAI questionnaire.