L-arginine is one of many amino acids the body needs to function properly. Taking it as a supplement can benefit the heart and muscles, but it may cause gastrointestinal side effects.

Like other amino acids, L-arginine plays a role in building protein. The body uses protein to help build muscle and rebuild tissue. It converts this amino acid into the chemical nitric oxide, which helps the blood vessels open.

Researchers have investigated the effectiveness of L-arginine in treating high blood pressure and chest pain as well as in improving breathing in patients with COVID-19 requiring hospitalization.

Keep reading to learn more about the potential therapeutic benefits of L-arginine and the research behind them.

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L-arginine is an amino acid that helps the body build protein.

It also releases nitric oxide into the blood. Nitric oxide acts to widen blood vessels in the bloodstream, which may help certain circulatory conditions, according to a 2016 review.

The substance also stimulates the release of insulin into the body.

A person’s body naturally produces L-arginine under typical circumstances. People also get additional L-arginine as part of their regular diet.

Food sources, such as red meat, fish, dairy, and eggs, contain low amounts of L-arginine that can help the body replenish its necessary resources. Plant-based sources can include pumpkin seeds, soybeans, lentils, and chickpeas.

Occasionally, a person’s need for L-arginine may exceed their body’s ability to produce or consume it naturally. This is often true for older adults or people with certain medical conditions.

In these cases, doctors may prescribe them artificial L-arginine in the form of oral medications, injections, or creams. Several potential health conditions may benefit from an increased intake of L-arginine.

Some people take L-arginine as a supplement. However, as with any supplement, a person should use it with caution.

Although healthcare professionals consider L-arginine safe in moderate doses, too much can cause severe side effects, including death. It is also important to understand how the supplement may interact with the body and additional medications before taking it.

L-arginine has two effects: it turns into nitric oxide and helps the body build protein.

These effects give L-arginine an array of potential benefits, including:

  • supporting heart health
  • reducing chest pain
  • helping build muscles
  • repairing wounds
  • improving male fertility

Although there are many claims about the benefits of L-arginine, not all of them have support from scientific studies.

Examples of benefits and uses of L-arginine from scientific research include the following:

  • Growth hormone reserve test: Healthcare professionals use L-arginine in tests to stimulate the pituitary gland. These tests can help determine if children are producing sufficient levels of growth hormone.
  • Reducing high blood pressure: A 2021 meta-analysis suggests L-arginine can help reduce high blood pressure.
  • Correcting hereditary disorders of urea synthesis: The body uses arginine in the urea cycle, which produces urea, a component of urine. The body may use this to correct certain hereditary disorders.
  • Preventing heart disease: According to a 2019 meta-analysis, L-arginine may be useful in preventing heart disease due to narrow blood vessels.
  • Treating erectile dysfunction: Low levels of L-arginine may have links to erectile dysfunction (ED). Researchers in a 2017 study hypothesized that this may be due, in part, to narrowed blood vessels. People often use L-arginine supplementation, sometimes with other treatments, such as sildenafil (Viagra), to treat ED.
  • Easing inflammation of the digestive tract in premature infants: L-arginine may help prevent necrotizing enterocolitis, a serious illness in premature infants, according to a 2017 study.
  • Reducing type 2 diabetes risk: Because L-arginine can help lower blood sugar, it may help control blood sugar in people with diabetes. A 2018 study found that taking L-arginine may reduce the risk or delay the onset of type 2 diabetes.
  • Treating peripheral arterial disease: Because of L-arginine’s effects in widening blood vessels, it may help those with peripheral arterial disease.
  • Treating pregnancy complications: L-arginine may help treat pregnancy complications, including preeclampsia, gestational hypertension, or high blood pressure.
  • Improving athletic performance: The results of a 2020 study suggest that L-arginine supplements may have a positive effect on aerobic and anaerobic exercise performance.

Additionally, L-arginine could help with many other health issues. However, more research is necessary to evaluate its potential to do the following:

There are several additional areas that researchers are interested in exploring regarding L-arginine and its effects on the human body.

With this in mind, anyone interested in taking L-arginine needs to talk with their doctor about the potential benefits and risks before using it.

Individuals should also fully understand and examine a manufacturer’s claims about their product before using it. The Food and Drug Administration (FDA) does not regulate dietary supplements as medication, so they may sometimes contain more or less than the dosage according to the label or bottle.

L-arginine has some potential side effects to consider when taking it as a supplement. Some of the more common and benign side effects can include:

However, L-arginine may result in some serious complications.

Risks and complications

L-arginine can have some potentially serious risks for certain groups of people.

These can include:

Although there are risks that correlate with L-arginine use, most research indicates it is safe for most people in small doses. However, the FDA does not monitor the safety or effectiveness of supplements, so it is important to choose a reputable brand that undertakes third-party testing.

Supplements are available to purchase online, but as with any supplement or medication, the risks may outweigh the potential benefits. Therefore, a person should consult a doctor or dietitian before taking L-arginine.

The amount of L-arginine a person should take can depend on their age, existing health conditions, and the reason for supplementation.

A 2018 study of 142 participants determined that a dosage of up to 30 grams (g) per day of L-arginine is safe in most adults. Participants in the study tolerated 15–30 g of the supplement without adverse effects.

Some medications and supplements may interact with L-arginine. People who take other medications or have health conditions should consult a doctor before taking it in supplement form.

A major benefit of obtaining L-arginine through diet is that it is difficult to get too much. Therefore, a person can generally avoid some of the side effects of consuming excessive amounts of L-arginine.

On the other hand, food consumption alone may not provide enough L-arginine to meet a person’s needs. Therefore, individuals should discuss their options with a doctor before changing their diet.

The most suitable natural sources for L-arginine include foods high in protein. For some people, animal proteins, such as red meat, chicken and turkey breast, pork loin, and dairy products, may serve as their primary source of L-arginine.

For people who do not eat meat, plant-based proteins that contain L-arginine include lentils, chickpeas, peanuts, pumpkin seeds, and soybeans.

Individuals who find they have insufficient L-arginine to meet their needs may wish to modify their diet to include foods rich in protein.

A dietitian or doctor may be able to make meal plan suggestions to boost a person’s natural intake of L-arginine before they need to take supplements.

L-arginine is an amino acid that the body needs to function properly. A person can obtain it through the diet by consuming animal proteins and some plant-based proteins. Individuals can also take L-arginine as a supplement.

Taking L-arginine supplements can support heart health, reduce blood pressure, lower blood sugar, and support athletic performance, among other benefits.

However, side effects of these supplements can include gastrointestinal issues and interactions with medications. Therefore, it is best to talk with a doctor before taking them.