Arginine is an amino acid most noted for its role with nitric oxide, blood vessel regulation, and athletic performance, but arginine does more than this. Learn more about this amino acid and its many important contributions to health and physiology.

Arginine is a semi-essential amino acid as it can be made to some degree in your body. During times of growth, such as infancy and puberty, and with physical stress, injury, or illness, there is a higher need for arginine, i.e. it becomes conditionally essential. Arginine affects cell division, hence the increased need for it during high repair needs as well as for growth and development.

Arginine is naturally produced and/or metabolized in the small intestine, liver and kidneys. It works with other amino acids like glutamine, glutamate, glycine, proline, and citrulline. It is metabolized in cytosol, the fluid inside cells, and affects mitochondria activity. Arginine also helps kidney metabolism with the blood urea nitrogen (BUN) cycle which helps detoxify and remove nitrogen wastes like ammonia.

Arginine, Nitric Oxide, and Blood Flow

Arginine helps produce nitric oxide. Arginine and nitric oxide metabolism is a prominent area of research because of its immense importance to health. Nitric oxide is a very important cellular signaling molecule that affects vascular tone or relaxation in all sizes of blood vessels. In addition, nitric oxide affects mitochondria function, growth and recovery, reproduction, blood sugar metabolism, insulin secretion, and more.

A primary site of nitric oxide production is the inner endothelial lining of blood vessels. Its presence allows relaxation of smooth muscles inside blood vessels which allows movement or perfusion of nutrients and oxygen into tissues. Arginine’s role in nitric oxide production provides substantial support for heart and blood vessel regulation, function, and vasodilation.

Arginine supports vascular health in the brain. Studies showed that it calms sympathetic nervous system stress, irritation, and microvascular constriction which helps natural capillary blood flow in the brain.

Women Health

During pregnancy, arginine stimulates protein synthesis and blood vessel growth in the placenta, uterus, and child. Human studies show that arginine enhances growth and development in the unborn child. A randomized controlled clinical trial found arginine helpful in support of blood vessel vasodilation and modulation of blood pressure during pregnancy.

In addition, arginine supplementation was shown to modify oxidative stress and inflammatory signals associated with obesity in women.

Men’s Health

Twenty years ago, TV commercials and ads featuring Senator Bob Dole discussed “the little blue pill” or Viagra to end concerns with “ED” or erectile dysfunction. Millions of men flocked to it. Viagra manipulates nitric oxide production.

Arginine is essential to produce beneficial nitric oxide for men’s sexual health and performance. Penile erections require blood vessel dilation, blood flow and relaxation of smooth muscle, mitochondria ATP production, and proper nervous system function that involves nitric oxide and arginine.

A number of clinical trials have demonstrated that arginine supplementation supports natural penile erection. Pycnogenols are often combined with arginine for enhanced vascular vasodilation and erectile support.

Arginine supplementation also affects men’s fertility as demonstrated in a randomized control trial. Men who supplemented with arginine experienced “enhanced sperm volume and concentration, motility, vitality, and morphology significantly versus placebo.” No adverse effects were reported. Other randomized trials with arginine reported improved sperm motility and concentration. Daily dose used was 1.4 grams per day.

In an open clinical trial, arginine combined with pycnogenol supported lower urinary tract and bladder health in men. This was again because of its role in nitric oxide and cellular signaling.

Athletics and Performance

Athletes often seek ways to enhance circulation and blood flow to help stamina and performance in sports. Arginine is an ergogenic aid because of its role with nitric oxide which increases blood flow and delivery of nutrients and oxygen to muscles. Arginine helps muscle growth and increases secretion of growth hormone making it popular for athletic performance and recovery. It also helps creatine production, which supplies energy for muscles during anaerobic/strength, power, and work activity.

A recent meta-analysis and systemic analysis on randomized trials found that arginine supplementation enhanced sports performance. A dose of 0.15 g/kg of body weight 60-90 minutes prior to aerobic or anaerobic workout improved overall capacity. For long-term aerobic sport benefits, participants used 1.5 – 2 grams/day for 4-7 weeks. For long-term anaerobic support enhancement, participants used 10-12 grams/day for 8 weeks.

Mitochondrial Support

Mitochondrial activity and energy production relies on many things including beneficial nitric oxide. Arginine helps restore nitric oxide production which helps mitochondria activity.

When mitochondria are stressed from high levels of free radicals and oxidative stress, low levels of nitric oxide often occurs. This distressed function leads to adverse changes in nerves, blood sugar, muscles, and increased lactic acid production that affect microvascular perfusion and blood flow. Arginine increases nitric oxide availability in tissues which aids muscle strength, exercise capacity and recovery, and blood sugar metabolism. It supports removal of nitrogen waste or ammonia and lactic acid.

Immune Support

Arginine directly impacts immune health in ways other than nitric oxide. Recent studies discovered that arginine is involved as a precursor to macrophages, a type of large white blood cell. Macrophages, which means “big eater,” are scavengers. Macrophages flow throughout the blood where they engulf and digest particles, dead cells, and debris on a daily basis. Arginine is needed to make macrophages.

Current research also demonstrated that arginine influenced immune response with regulation of T lymphocytes function and Natural Killer cell (NK) activity which help immune system recognition, regulation, and clean-up.

Macrophage activity, T-lymphocyte function, and NK cell activity occur daily, but these functions are ramped up during times of stress. During high immune and respiratory support needs and repair, arginine becomes an essential amino acid. Supplemental use may be as much as 15-35 grams/day. A synergistic effect occurs with the inclusion of the amino acid glutamine which also supports immune and muscle energy fortification.

Arginine is one nutrient that plays a critical role in nitric oxide metabolism that affects blood vessel dynamics, mitochondria function, pregnancy health for mom and baby, men’s sexual and urinary health, athletic performance and recovery along with immune modulation. These studies listed provide a small sampling of current highlights.

Arginine rich foods include shellfish, fish, meat, spinach, dairy, eggs, with lesser amounts found in grains, beans, legumes, and nuts. It may also be supplemented. Arginine dosage up to 30 grams per day or more for long-term use has been found to be safe. Natural arginine is more than just a “little blue pill”. It is amino acid necessary during times of stress, growth, repair, challenge and performance.