L-Arginine is a conditionally essential amino acid found in the diet. Good food sources of L-arginine include eggs, meats, milk, soy proteins, peanuts and walnuts.

Conditionally essential means it is particularly important during periods of illness and chronic conditions like hypertension, kidney disease and type II diabetes. These states tend to be characterized by an increase in the enzyme that degrades L-arginine (known as arginase) resulting in a deficiency and can be partially remedied by an increase in L-arginine intake. Deficiency can also impair immunity, hair and muscle growth.

It is a dietary supplement that is also popular among athletes because it is the amino acid that directly produces Nitric Oxide which is involved in increasing blood flow through vasodilation.

L-Citrulline is another supplementation option because it is converted into arginine in the kidneys. It also has a better absorption rate than L-arginine and is able to increase levels of plasma arginine more effective than arginine itself. For long-term health-related supplementation, L-citrulline may be a better supplementation option than L-arginine.

In general, much research suggests a modest reduction in blood pressure and improvement in blood flow from chronic citrulline supplementation, particularly for those with hypertension and other cardiovascular problems. To enhance sports performance, take 6,000 – 8,000 mg of citrulline malate about an hour before exercise. On days that you don’t exercise, it can be broken up into smaller doses.


The standard pre-workout dose for L-arginine is 3-6g.

To maintain elevated arginine levels throughout the day, arginine can be taken up to three times a day, with a combined dose total of 15-18g.


Arginine is involved in two regulatory cycles (urea and nitric oxide) and can be converted into a few other bioactive molecules such as creatine or agmatine. Agmatine acts as a novel signalling molecule in the brain mostly related with cognition and pain perception.

Arginine promotes resting state growth hormone secretion (can be taken before bed time). It has a synergistic effect when taken with lysine.

Maybe useful in the treatment of erectile dysfunction.

he ageing brain appears to have reduced concentrations of nitric oxide and arginine may be involved in neurogenesis.

Cardiovascular health: may reduce blood pressure but no significant influence on heart rate has been seen. In those with peripheral artery disease, symptoms seems to be slightly improved with short term use of L-arginine.

It could also possibly reduce stress induced anxiety. Nitric oxide modulates cortisol and  stress could induce an arginine deficiency.

Glucose tolerance:

A slight reduction in fat mass has been noted with long term usage. An increase in insulin secretion has been noted, this is both due to arginine being a secretagogue (enhances insulin sectetion) and prolonged usage in those with impaired glucose tolerance may regenerate pancreatic beta cells.

Exercise performance

Maybe able to increase anaerobic physical performance both endurance and power (high intensity). It may reduce the oxygen cost of exercise and decrease ammonia, thereby improving performance and delaying fatigue. Ideally taken in capsule or powder form on an empty stomach 30 minutes before workout.

Anti oxidant

It appears to have an indirect antioxidant role and increases superoxide dismutase concentrations.

Possibly enhances wound healing rates.


The observed safety limit, the highest dose in which one can be relatively assured that no side effects will occur over a lifetime, has been suggested at being 20g of arginine a day in supplemental form (above food intake). Higher doses have been tested and well tolerated, but no evidence exists to suggest their safety in all populations across a lifetime. It may cause diarrhoea if taken in a bolus dose of 10g and above at a time.

~ Shweta Bhatia, Registered Dietitian, Mind Your Fitness!

Barbara Melton

Barbara Melton

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