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L-Arginine: The Missing Ingredient for Performance and Immune Enhancement

Is it possible to enhance blood circulation, cardiac function, pump up the immune response and aid in muscle development with one ingredient?  L-arginine may just prove to be that one nutrient that is lacking from so many diets, impacting the health of people, pets and horses.  Whether if you are an Olympic athlete or just one seeking health solutions, L-arginine supplementation may prove to be of significant benefit on many levels.  Let’s take a look at the basics and what clinical research has to show.

Amino acids are the structural building blocks of protein, with each one having its own impact on health, sometimes from multiple levels.  L-arginine is considered to be a ‘semi-essential’ amino acid in that the body is able to synthesize it from other amino acids.  Arginine is also acquired from the diet from dairy and plant foods, in variable levels.  What research has shown is that in most cases of healthy individuals, the achieved arginine levels between diet and natural synthesis are considered to be adequate, but we have to raise the question as to what the definition of a truly healthy individual is and what those levels are?  Research is a little vague on this topic and has suggested normal levels, but there are too many variables to make this carry over from one individual to the next.  What has been shown is that the natural synthesis of L-arginine by the body is insufficient to meet typical demands and thus diet is considered to be the sole source of the amino acid.

When we consider the poor diet that most of us consume, which is often nutrient void, as well as the many health conditions that are becoming more prevalent, we need to question the value of supplementation.  This holds true not only for us, as humans, but also for our pets and equine companions as they are often exposed to food sources that are becoming deficient in many nutrients for various reasons.  It could be possible that supplementing various amino acids in our diets, including L-arginine, could prove to be very beneficial for a host of conditions.

Impact of L-Arginine on Health

  1. L-arginine is directly tied into nitrogen metabolism and ammonia detoxification within the body. Ammonia is generally a byproduct of protein metabolism and keeping levels low is critical to overall health.
  2. L-arginine is the precursor to nitric oxide formation, which contributes to vasodilation (relaxation of blood vessels).  This vasodilation then can contribute to overall lowering of blood pressures, enhance blood circulation and improve cardiac function.
  3. L-arginine directly impacts immune function by enhancing natural killer cell and lymphocyte activity.
  4. L-arginine impacts endocrine function directly, with one area in particular being Growth Hormone (GH).

Considering all of these benefits, let’s now take a look at what research has to show.

Cardiac Benefits:

  • L-arginine supplements increased production of Nitric Oxide (NO) resulting in vasodilation and has been shown to benefit those patients with active hypertension (1)
  • L-arginine supplementation reduced clinical signs of angina in patients with active clinical signs and increased their exercise capacity. (2,3)
  • L-arginine supplementation reduced the clinical signs of congestive heart failure (CHF) resulting in improved blood flow and condition stability (4)
  • L-arginine supplementation improved exercise duration in patients with CHF (5)
  • L-arginine supplementation also improved renal function and blood flow in patients with CHF (6)
  • L-arginine supplementation reduced factors associated with atherosclerotic plaque formation due to increased nitric oxide formation, decreased platelet aggregation, decreased monocyte migration, decreased smooth muscle proliferation and decreased vasoconstriction…all factors tied in with atherosclerosis. (1)

Tissue Healing and Repair:

It is well known that severe illness, sepsis, trauma and post operative healing can result in depletion of L-arginine within the body.  This subsequent depletion has been theorized to contribute to overall poor recovery in a variety of conditions.  In most cases of critical illness, Total Parenteral Nutrition, provided to the patients that are not eating has been of value, but often is void of critical L-arginine which may enhance overall recovery.

  • L-arginine supplementation has shown to increase healing time, reduce post operative infection risk, decrease length of hospital stay and enhance overall immune function in patients with critical injuries, illness or post-operative. (1,7,8)

Cancer Support:

L-arginine supplementation has shown marked benefit in patients with cancer, likely due to overall positive impact on immune function, which may help to reduce tumor burden and aid in overall recovery. (1)

Exercise Performance:

L-arginine supplementation has been shown in research to enhance physical exercise capacity and delaying onset of fatigue, possibly reducing lactic acid production which is often a limiting factor to intensity and duration.  Supplementation has also been shown to improve antioxidant levels during exercise, which is often depleted and predisposes many athletes to illness.(9)

Neurodegenerative Conditions:

L-arginine supplementation has been shown to enhance central nervous system function and reduce the impact of neurodegenerative conditions, likely through improved blood circulation and antioxidant defenses.  These findings may support the use of L-arginine in Alzheimers patients. (10)

So why supplement with L-arginine?

Honestly, we have to look at two categories of individuals and animals when it comes to supplementation; health preservation versus condition management.  The difference between two is that one group is looking for prevention purposes to maintain optimal health, while the other group may actually have a health condition that creating excess demands on the body, creating a need for higher levels of supplementation.

In humans, L-arginine supplementation may enhance overall cardiovascular health, blood flow and support healthy immune function.  In those individuals with current health concerns, arginine supplementation may help to reduce blood pressure, improve cardiovascular health and function, plus support immune function which may aid in overall healing and recovery from a variety of conditions.  Again, dependent on which group one falls into, L-arginine supplementation may prove very beneficial, but the question comes as to which amount is best?  Just like many other nutrients and amino acids, dosing is dependent on the condition presented and level of severity. In research studies, doses have varied from 500 mg per day to as much as 30 grams with clinical benefits.  Likely, prevention type strategies would require lower daily levels while those with more critical concerns may benefit from higher doses.

In horses, L-arginine supplementation may enhance overall exercise performance, recovery, help to improve cardiac function and blood flow, while potentially reducing the impact of lactic acid.  Considering the ability of arginine to enhance circulation and support the immune system, supplementation may prove beneficial in wound repair, surgical recovery and even tendon healing.  By enhancing circulation, we can improve the delivery of nutrients to the tissue for healing purposes.  The immune function is also needed in the process of tissue repair, which helps to clear dead tissue and fluid accumulation, all supported by L-arginine.  L-arginine supplementation may also prove valuable in the management of laminitis, due to improved blood flow and vasodilation to the digital region. Doses again vary dependent on the level of condition being managed.


Like all nutrients, there is no exact dose of supplementation that is recommended which will aid all conditions.  The amino acid L-arginine has proven to be of clinical value in a variety of conditions, but the dosing in research studies has varied.  One thing to keep in mind is that often, it is not ONE nutrient or amino acid that is beneficial, but a synergism between many.  In some cases, with an over consumption of a single nutrient, we can create imbalances in amino acid metabolism and overall health.

As a veterinarian, horse owner and personal health advocate, I do find supplementation of L-arginine valuable, helping to make many conditions more manageable through restoration of health.  Believing that the use of multiple nutrients is best to achieve benefits, we utilize L-arginine at modest levels in combination with other vital amino acids and sources of protein, helping to enhance effect and maintaining balance.

Cur-OST® Immune Human:  Provides L-arginine supplementation with L-glutamine, L-carnitine and mushroom beta-glucans for immune enhancement.

Cur-OST® EQ Immune & Repair:  Provides L-arginine supplementation with L-glutamine, L-carnitine and mushroom beta-glucans for immune enhancement.

Cur-OST® Nourish EQ: Provides L-arginine supplementation with L-glutamine, L-carnitine, L-creatine in a pea protein base for provision of many amino acids for energy and tissue healing benefits.

Cur-OST® Immune SA:  Provides L-arginine supplementation with L-glutamine, L-carnitine and mushroom beta-glucans for immune enhancement.

We also offer bulk L-Arginine for sale as an individual ingredient.

In our patients, I have found tremendous value in managing tendon injuries and laminitis, decreasing the time involved in recovery and return to use.  For the long term, I will generally utilize these formulas to support overall tissue health and blood flow, in combination with one of our Cur-OST® EQ anti-inflammatory formulas, helping to reduce constant inflammation which increases risk of injury.  The same approach can be utilized to help manage a variety of health conditions which could benefit from improved blood circulation and immune enhancement. Amino acid supplementation and L-arginine supplementation may also theoretically enhance recovery from many severe illnesses and septic conditions, including colic and post surgery, through health restoring measures mentioned above.

For prevention or condition management situations, L-arginine supplementation may prove to be very beneficial to maintaining and restoring health.

Our goal is to improve health through education.  I hope you find this information helpful.

All my best,

Tom Schell, D.V.M.

Nouvelle Research, Inc.


  1. L-Arginine Monograph, Alt. Med Review, vol 10, no 2, 2005
  2. Blum, A et al. Clinical and inflammatory effects of dietary L-arginine in patients with intractable angina pectoris. Am J Cardiol. 1999:83:1488-90
  3. Ceremuzynski, L et al. Effect of supplemental oral L-arginine on exercise capacity in patients with stable angina pectoris. Am J Cariol 1997: 80;331-333
  4. Rector, TS et al. Randomized double-blind, placebo controlled study of supplemental oral L-arginine in patients with heart failure. Circulation 1996:93; 2135-2141
  5. Watanabe, G et al. Effects of oral L-arginine on renal function in patients with heart failure. J Hypertens 2000:18; 229-234.
  6. Yousuffudin, M et al. A short course of L-arginine improves exercise capacity and endothelial function in patients with heart failure. J Am Coll Cardiol 2001:211A
  7. Bower, RH et al. Early enteral administration of a formula (Impact) supplemented with arginine, nucleotides, and fish oil in intensive care unit patients. Crit Care Med 1995:23; 436-439
  8. Weimann, A et al. Influence of arginine, omega-3 fatty acids and nucleotide supplemented enteral support on systemic inflammatory response syndrome and multiple organ failure in patients after severe trauma. Nutrition 1998:14; 165-172
  9. Shan, L et al. L-arginine supplementation improves antioxidant defenses through L-arginine/Nitric Oxide pathways in exercised rats. J Appl Physiol. 1985, 115 (8), 1146-55
  10. Virakar, M et al. L-arginine and nitric oxide in CNS function and neurodegenerative diseases. Crit Rev Food Sci Nutr. 203; 53(11) 1157-67

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