L-Arginine - A Key Factor In the Production of Nitric Oxide
In 1988, Dr. Salvador Mondaca of England, announced that L-arginine is the substance that triggers the formation endothelium-derived nitric oxide. This is a semi-essential amino acid that can be found in protein. It is considered semi-essential because our bodies produce some of it, but we need additional quantities from the food we eat or nutritional supplements.
This announcement was particularly exciting for Dr. John P. Cooke, head of vascular medicine at Stanford University School of Medicine. He wanted to find out what would would happen if L-arginine was given to people with high cholesterol. Could this boost the production of nitric oxide? If that was the case, then there would be a simple way to improve blood vessel health. He wanted to immediately put these questions to the test, and successfully confirmed his hypothesis in animals. He then wanted to confirm those results in people with high cholesterol. What he found was that saline alone had no effect on blood vessels to relax, but the blood flow of people receiving the arginine returned to normal within minutes of the infusion.
These results were first met with skepticism by the scientific community, however, over the next few years, other researchers confirmed these results with tests of their own. In the early 1990's it became clear to the scientific community that this amino acid could improve blood flow and blood vessel relaxation in patients with certain cardiovascular problems.
A little history about protein helps to understand the importance of amino acids. Protein is a complex organic substance found in many foods. It is vital for maintaining our body's tissue, helping form muscles and organs, healing wounds, energy, and regulating many physiological processes, such as movement of oxygen and nutrients throughout the body. Protein is the body's main building material. When you eat protein rich food, digestive enzymes in the small intestine break the protein down into its simplest form, which are the many amino acids. L-arginine is one of these amino acids. L-citrulline is another one, and they are both key factors in boosting nitric oxide production.
It is extremely important when considering an arginine supplement, that one of its components is L-citrulline. Many supplement products for arginine do not include L-citrulline, which would not allow you to receive the optimal benefits possible from a supplement designed to boost nitric oxide production. There is an increasing amount of research evidence confirming that the combination of L-arginine and L-citrulline to boost nitric oxide production, helps to protect or restore your cardiovascular health.
Nitric oxide derived from arginine is directly or indirectly involved in almost every cellular response and health condition there is. It affects both the cardiovascular system and the immune system, as well as hormone function to nerve function. Nitric oxide is 1,000 times more powerful than any naturally occurring antioxidant in the body. Its antioxidant properties are particularly important for numerous body systems and may help protect against heart disease, stroke, cancer, and diabetes, as well as slowing the aging process. It also benefits the cardiovascular system, by controlling blood pressure and reducing plaque formation through the increased production of nitric, which keeps arteries relaxed and pliable.
Arginine improves memory, especially long-term memory, and may help to diminish or reverse the effects of dementia and Alzheimer's disease. It boosts human growth hormone (HGH) production, which has anti-aging benefits, including preservation of lean muscle mass and bone density. It also improves communication between nerve cells and the brain cells, and enhances immune function and protecting against bacterial infections.
It benefits people with diabetes due to the many complications associated with this disease, such as poor circulation and blindness, which are due to vascular problems. It also helps regulate insulin secretion in the pancreas. This is especially important news due to the near epedemic of type II diabetes in the U.S.
Arginine is helpful in treating asthma by opening pulmonary pathways for easier breathing and the treatment of lung disorders. Another benefit is helping to heal hemorrhoids by relaxing the hypertonic sphincter muscles. It can be beneficial in cardiovascular and lung damage caused by tobacco use, due to increased nitric oxide production, which is approximately half the level in smokers as non-smokers.
Research shows that arginine helps to accelerate wound healing and post-surgery recovery in the elderly. It may improve athletic performance, as well, due to its ability to boost exercise tolerance resulting from the vasodilation effect of increased nitric oxide production.
Arginine may also improve the function of the prostate, and has been used as a treatment for irritable bowel syndrom (IBS). It has been used to reduce the occurrence of ulcers, however, it does not affect gastric acid production. L-arginine's protective effect on kidneys may be beneficial for people with diabetes.
Ongoing research continues to support the many benefits of arginine supplementation. In a study at Hannover Medical School, scientists looked at the effects of L-arginine on peripheral artery disease (PAD), which is manifested by the narrowing of blood vessels to the leg arteries, which leads to severe leg pain in the calf muscles while walking (a condition called "intermittent claudication"). The researchers gave the patients either two daily infusions of arginine (8 grams each), prostaglandin E1 (a vasodilator), or no treatment for three weeks. The individuals that received arginine experienced greater improvement regarding their pain-free walking distance and their absolute walking distance than the patients on prostaglandin, while the control patients showed no significant change. Arginine also improved vessel dilation in the thighs associated with endothelial function, while prostaglandin provided no improvement. The researchers concluded, "Restoring nitric oxide formation and endothelium-dependent vasodilation by L-arginine improves the clinical symptoms of intermittent claudication in patients with peripheral arterial occlusive disease."
Christiaan Barnard, a South African surgeon, conducted the first human heart transplant in 1967. Since that time, this procedure has dramatically evolved and improved, and the American Heart Association estimates that ~2200 are performed annually in the United States. Fortunately, survival rates are now quite high, mainly due to the development and use of immunosuppressive drugs (eg, cyclosporine) that help prevent organ rejection. One complication of heart transplants, however, is reduced exercise capacity, which is important because it can lead to lower quality of life. Although clinicians do not know why this occurs, reduced exercise capacity may be linked to imbalanced production of nitric oxide (NO; a vasodilator) and endothelin-1 (a vasoconstrictor), which has been related to cyclosporine use. Specifically, cyclosporine has been shown to decrease NO and increase endothelin-1 production in blood vessels. Because the body produces NO from the amino acid L-arginine, the researchers speculated it was possible that L-arginine supplementation might benefit these patients. To test this hypothesis, a team of French researchers studied the effect of L-arginine supplementation on exercise capacity in patients who had undergone heart transplant surgery.
Patients received 6g of L-arginine twice daily for six weeks, or a placebo for six weeks. Another group of healthy sedentary men not taking L-arginine were also studied as a control group.
The results showed an increase in exercise capacity with the arginine group, while there was no change in the placebo and control groups. Resting and maximal heart rates decreased in only the arginine group, which suggested more efficient functioning of the heart. These changes were associated with increased blood nitric oxide concentrations. An improved quality of life was inferred in only this group.
