L-Arginine: Benefits, Side Effects And Everything Else You Need to Know (2024)

L-arginine is categorized as a conditionally essential (or semi-essential) amino acid, which means that under normal conditions, the body can produce sufficient amounts of it to fulfill its needs, explains Lon Ben-Asher, a registered dietitian nutritionist at Pritikin Longevity Center in Miami.

“However, under situations of illness, stress or pregnancy or trauma, the body’s demand for L-arginine may exceed its ability to produce it, making it essential to obtain from dietary sources or supplementation,” says Ben-Asher.

L-arginine is in a variety of food sources, including:

• Animal proteins, like fish, chicken, red meat and dairy
• Plant proteins, such as soy and peanuts
• Nuts and seeds, including walnuts and pumpkin seeds
• Whole grains like oats and wheat germ

In addition to making proteins, our body needs L-arginine to produce nitric oxide (NO), which is essential for regulating blood pressure, says Susan Hewlings, Ph.D., a registered dietitian and vice-president of Research Affairs at Radicle Science in Del Mar, California.

“Nitric oxide is made in our vascular endothelial cells (the inner cellular lining of veins and arteries) using L-arginine as a substrate (a substance that reacts with an enzyme to form a chemical bond),” says Dr. Hewlings. A vasodilator, nitric oxide helps dilate blood vessels, making it easier for blood to flow and keeping blood pressure levels in a healthy range.

L-arginine also regulates T-cell metabolism, meaning it helps T-cells survive—which is crucial for our immune system, says Dr. Hewlings. T-cells are a type of white blood cell, or lymphocyte, that destroy cells in the body that have become cancerous or invaded by viruses.

Additionally, L-arginine helps trigger the release of insulin (a hormone that shuttles glucose to cells to be used as energy) and growth hormone (responsible for growth and metabolism) in the body.

L-arginine may be taken in supplement form to boost the immune system, support cardiovascular health, enhance exercise performance and more, says Ben-Asher. Here are six research-backed benefits of L-arginine.

Athletic Performance

Many athletes and bodybuilders use L-arginine to improve the delivery of oxygen to the muscles from the blood, says Ben-Asher. During exercise, muscles need a constant supply of oxygen, which increases with exertion. Maximal oxygen consumption (VO2 max) measures how much oxygen your body can use while exerting as much energy as possible. In other words, the higher your VO2 max, the greater your fitness level.

A 2021 meta-analysis found that L-arginine may increase VO2 max, helping to support its use as an exercise performance enhancer^[1]Rezaei S, Gholamalizadeh M, et al. The effect of L-arginine supplementation on maximal oxygen uptake: A systematic review and meta-analysis. Physiol Rep. 2021;9(3):e14739. .

L-arginine supplementation may also improve aerobic and anaerobic performance, says Dr.Hewlings. According to a 2020 meta-analysis, taking L-arginine 60 to 90 minutes before working out is most effective; it may take four to eight weeks of supplementation to experience results^[2]Viribay A, Burgos J, et al. Effects of Arginine Supplementation on Athletic Performance Based on Energy Metabolism: A Systematic Review and Meta-Analysis. Nutrients. 2020 2;12(5):1300. .

Blood Sugar Management

L-arginine is a precursor of nitric oxide, which plays essential roles in cellular function—including the synthesis and secretion of insulin, says Ben-Asher. Increasing the availability of nitric oxide through L-arginine supplementation may improve the function of insulin-using cells in the pancreas by helping them use glucose from the blood more effectively, he says.

One small study of middle-aged individuals with prediabetes and metabolic syndrome found that supplementation with L-arginine for 18 months decreased the risk of diabetes over nine years, suggesting it may be a useful tool in diabetes prevention^[3]Monti LD, Galluccio E, et al. Decreased diabetes risk over 9 year after 18-month oral L-arginine treatment in middle-aged subjects with impaired glucose tolerance and metabolic syndrome (extension evaluation of L-arginine study). Eur J Nutr. 2018;57(8):2805-2817. . On the other hand, a newer study from 2021 found that higher intakes of supplemental L-arginine (more than 5.4 grams) over the course of five years may actually increase the likelihood of type 2 diabetes—so it’s important to speak with you doctor about the proper dosage and length of time one should supplement.

Blood Pressure Management

Because L-arginine is needed to synthesize nitric oxide, a crucial vasodilator, it may support healthy blood pressure, says Dr. Hewlings. “By helping our blood vessels dilate, nitric oxide increases blood flow,” she says.

In a recent meta-analysis, L-arginine supplementation demonstrated significant improvements in both systolic and diastolic blood pressure in individuals with and without hypertension across various body mass index (BMI) categories and health status^[4]Mirmiran, P., Bahadoran, Z., Gaeini, Z. et al. Habitual intake of dietary L-arginine in relation to risk of type 2 diabetes: a prospective study. BMC Endocr Disord. 2021;21:113. .

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Recovery From Illness and Trauma

L-arginine is critical during times of illness and trauma, says Ben-Asher. He explains that your L-arginine needs increase significantly in these circ*mstances, and your body can’t keep up on its own.

When L-arginine is depleted, immune function and blood flow can become impaired, says Ben-Asher. To avoid these potential complications, he says arginine supplements are given (orally or intravenously) to treat various conditions.

According to research, these conditions include wound healing, liver disease, congestive heart failure, kidney dysfunction, bladder inflammation, head and neck cancer, high blood pressure, migraines and more^[5]Shiraseb F, Asbaghi O, et al. Effect of l-Arginine Supplementation on Blood Pressure in Adults: A Systematic Review and Dose-Response Meta-analysis of Randomized Clinical Trials. Adv Nutr. 2022 1;13(4):1226-1242. .

Erectile Dysfunction

A recent research review found men with mild-to-moderate erectile dysfunction (ED) who received daily L-arginine supplements experienced significant improvements in sexual function^[6]Rosenthal M, Carrott C, et al. Parenteral or Enteral Arginine Supplementation Safety and Efficacy. The Journal of Nutrition. 2016;146(12):2594S-2600S. . But because dosage and treatment duration were inconsistent, the efficacy and safety of arginine supplements for ED remains unclear, says Ben-Asher.

Preeclampsia

Taking L-arginine during pregnancy may help with preeclampsia (a condition marked by persistent high blood pressure and increased risk of stroke, organ damage and preterm birth), notes Ben-Asher.

A small, double-blind, placebo-controlled trial among pregnant women at high risk for preeclampsia found that those who supplemented with L-arginine experienced a reduced incidence of the condition^[7]Rhim HC, Kim MS, et al. The Potential Role of Arginine Supplements on Erectile Dysfunction: A Systemic Review and Meta-Analysis.. J Sex Med. 2019;16(2):223-234. A slightly older research review from 2014 concludes that while L-arginine may help prevent and treat preeclampsia, further research is needed—although it can be difficult to find studies around pregnant individuals specifically^[8]Camarena Pulido EE, García Benavides L, et al. Efficacy of L-arginine for preventing preeclampsia in high-risk pregnancies: A double-blind, randomized, clinical trial. Hypertens Pregnancy. 2016;35(2):217-25. .

L-Arginine dosage varies based on factors such as age, weight, health status and the specific reason for supplementation, says Ben-Asher. For example, 2.5-gram daily doses may be effective for ED, whereas 3-gram daily doses may help with preeclampsia.

Research indicates that doses of up to 30 grams daily are well-tolerated, but Ben-Asher advises consulting a health care professional to establish the best dosage for your needs.

Common side effects of L-arginine include the following, according to Jennifer Bourgeois, Pharm.D., a functional medicine specialist and health and pharmacy expert at SingleCare:

• Abdominal pain
• Bloating
• Nausea
• Diarrhea
• Headache
• Flushing
• Low blood pressure
• Insomnia

Additionally, the following medications may interact with L-arginine, notes Dr. Bourgeois:

• Blood pressure medications, including isoproterenol, ACE inhibitors, angiotensin receptor blockers (ARBs) and antihypertensives
• Diabetes medications
• Erectile dysfunction medications
• Anticoagulant or antiplatelet medications
• Potassium-sparing diuretics

The bottom line? L-arginine offers several potential benefits, but it’s crucial to approach its supplementation with caution and seek a health care provider’s advice to ensure safe and effective usage, particularly if you’re taking prescription medications, says Dr. Bourgeois.