Plasma Arginine Research Analysis

Human Effect Matrix

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what supplements affect plasma arginine

Grade	Level of Evidence [show legend]
	Robust research conducted with repeated double-blind clinical trials
	Multiple studies where at least two are double-blind and placebo controlled
	Single double-blind study or multiple cohort studies
	Uncontrolled or observational studies only

Level of Evidence ? The amount of high quality evidence. The mo re evidence, the more we can trust the results.	Outcome	Magnitude of effect ? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.	Consistency of research results ? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.	Notes
	Arginine	Minor	Very High See all 6 studies	Supplemental L-Arginine increases plasma L-Arginine. The spike in plasma L-arginine concentrations may be slightly more than that seen with L-citrulline, but the latter lasts longer and is thus more effective
	Citrulline	Notable	Very High See 2 studies	Citrulline can increase plasma arginine concentrations, and due to acting as a resevoir of arginine it is actually more effective overall at increasing plasma arginine than arginine itself (acute peaks are still observed to a higher level with arginine supplementation).

All comparative evidence is now gathered in our A-to-Z Supplement Reference.

The evidence for each separate supplement is still freely available here.