L-arginine is an amino acid present in many dietary supplements. Amino acids are the building blocks of proteins and are divided into essential and nonessential categories. Nonessential amino acids are made in the body, but essential amino acids are not. As such, they must be provided through dietary intake. L-arginine is considered semi-essential or conditionally essential, meaning that it becomes essential under certain circumstances and conditions, including pregnancy, infancy, critical illness, and trauma.
A 2019 review of 10 studies found that taking arginine supplements in doses ranging from 1.5–5 grams daily significantly improved erectile dysfunction, compared with a placebo or no treatment.
Other research on the use of L-arginine for specific conditions shows:
• Angina: Studies suggest that L-arginine might decrease symptoms and improve quality of life in people with a mild to severe form of this type of chest pain.
• High blood pressure (hypertension): Some research has shown that oral L-arginine can lower blood pressure in healthy people, people with mild blood pressure elevation and diabetes, and in people with a type of high blood pressure that affects the arteries in the lungs and the right side of the heart (pulmonary hypertension). Infusions of L-arginine also appear to lower blood pressure in people with hypertension.
• High blood pressure during pregnancy: Some studies show that L-arginine infusions may lower blood pressure in pregnant women who develop high blood pressure.
• Preeclampsia: L-arginine infusions may lower blood pressure in women with this pregnancy complication. Some research shows that taking oral L-arginine might help prevent preeclampsia in pregnant women.
• Peripheral arterial disease (PAD): When taken orally or by infusion for a short period of time, L-arginine may improve symptoms and blood flow in people with this circulatory disease.
How should I take L-arginine?
Doses of L-arginine vary widely depending on what it’s being used to treat. For example, studies investigating the effects of L-arginine on blood pressure have used doses of 6–30 grams per day for 2–24 weeks.
In those with erectile dysfunction, research has suggested that supplementing daily with 1.5–5 grams of L-arginine may significantly improve symptoms. When used to treat preeclampsia, the dose typically ranges from 3–4 grams daily for up to 12 weeks, or until delivery under a doctor’s supervision. L-arginine may also be given intravenously to pregnant women with high blood pressure in the clinical setting.
Although higher doses are often used in research and clinical settings, it’s recommended that daily dosing of L-arginine be kept under 9 grams per day to avoid potential gastrointestinal side effects, including nausea, diarrhea, and bloating. Like other single amino acids, it’s recommended to take L-arginine between meals for maximum absorption.
Specific information regarding safety and efficacy during pregnancy and breastfeeding is lacking, although several trials have been conducted in pregnant women without notable ill effects.
How Long Does It Take For L-Arginine To Work?
Amino acids like L-Arginine are absorbed into the body in just 30 minutes. Studies reveal that dietary L-arginine is absorbed in the small intestine and transported to the liver, where the major portion is taken up and utilized in the hepatic urea cycle; however, a small part of dietary L-arginine passes through the liver and is utilized as a substrate for NO production.
Studies also reveal that peak concentration of L-Arginine is achieved 1 Hour after oral administration of the supplement. How quickly it works depends on the condition you are treating. For example, if you are taking oral L-arginine for the management of pain and some symptoms of bladder inflammation, it can take up to 3 months to see improvements.
What are the side effects of L-arginine?
For certain groups of people, there may be some risks involved in taking L-arginine as a supplement. L-arginine has some potential side effects to be aware of when taking it as a supplement. Some of the more common and benign side effects include:
• abdominal pain
• airway inflammation
• allergies
• bloating
• blood abnormalities
• diarrhea
• gout
• low blood pressure
• worsening of asthma
However, L-arginine may result in some serious complications that must be considered.
Risks and complications
L-arginine has some potentially serious risks for certain groups of people.
These include:
• difficulty controlling blood pressure during surgery
• increased risk of death after a heart attack
• negative interaction with certain medications, including Viagra and blood pressure medications
• serious illness or death in children and infants
• worsening of herpes flares.
Although there are risks associated with L-arginine, most research indicates it is safe for people to take in small doses. The U.S. Food and Drug Administration (FDA) does not monitor the safety or effectiveness of supplements, so it is important to choose a reputable brand.
