A cornucopia of confusion surrounds the benefits of taking L-arginine supplements. Also called just "arginine," there's some evidence that this amino acid may lower blood pressure and improve heart health, but there's little agreement among experts about safe dosage or its interaction with alcohol.
What Is L-Arginine?
"L-arginine is an amino acid, and our bodies need amino acids to build protein," says Amitava Dasgupta, PhD, a clinical toxicologist and professor at the University of Texas Medical School in Houston. "It is called an 'essential' amino acid because our bodies cannot produce it, so we have to get it from diet."
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You likely already get enough arginine from food. The U.S. Department of Agriculture (USDA) dietary guidelines suggest that meal plates be one-half full of vegetables and carbohydrates, and one-quarter full of protein, such as fish or meat. "If you eat a balanced diet, there is no L-arginine deficiency," Dasgupta says.
According to the Yale School of Medicine, nuts are a good source of arginine, which can improve cardiovascular health and lower your risk for blood clots. Need to go nut free? A February 2016 study in Food Chemistry found that chickpeas contain substantial arginine, another tasty food option for dips and salads.
Arginine supplements might benefit those who are severely ill and unable to eat in a healthy way, but otherwise, "L-arginine deficiency is very, very rare," Dasgupta explains.
Read more: Foods High in L-Arginine
What the Evidence Says
Research that looks into the safety and effectiveness of L-arginine runs the gamut — exploring its possible impact on diabetes to cavities to athletic performance, and much more. The U.S. National Library of Medicine outlines more than 50 areas that L-arginine has been studied.
While there's evidence for L-arginine's possible benefits for chest pain (angina), erectile dysfunction, blood pressure, blood flow and a serious digestive disorder in premature infants called NEC, most other areas of study show mixed results and do not provide evidence for its use.
Misconceptions are wide-ranging. "There is no scientific evidence L-arginine will help to grow hair, increase muscle mass or make veins look bigger," says Dasgupta. "There is no evidence it helps with weight loss. These are all rumors."
The reasons for these varied results are not clear, and safe dosages are not yet completely understood by scientists. The jury is still out — it's a good idea to get your doctor's perspective before taking arginine supplements.
Other Things to Consider
Does arginine affect the kidneys? A March 2019 report in the International Journal of Case Reports & Short Reviews describes how a woman taking arginine supplements ended up with acute kidney injury. "There is no scientific evidence it helps the kidneys," Dasgupta says. Arginine is involved in the body's protein synthesis, and "too much protein of any kind can pressure the kidneys," he says. "Any high-protein diet can have an adverse effect on the kidneys."
As for mixing arginine and alcohol, "I know of no scientific evidence that mixing it with alcohol is unsafe," Dasgupta says. However, he notes that USDA dietary guidelines suggest that men have not more than two drinks a day and women no more than one drink a day, and "for people following the guideline of moderate drinking, there is no known interaction between L-arginine and alcohol."
Although there's no evidence that it's unsafe to mix alcohol and arginine, alcohol consumption does threaten arginine's end game, which is to produce nitric oxide — a necessity for good health. A July 2016 study in the journal Chest showed that alcohol does its damage like a predictable seesaw: Nitric oxide levels decreased as alcohol intake increased.
Nitric oxide is produced from arginine, notes Jody Bergeron, RN, BSN, a nurse with Cape Cod Health Care in Massachusetts and a guest blogger for the American Society for Nutrition. In an article for the society, she explains that nitric oxide helps blood vessel walls relax and dilate, reducing the risk of heart disease and stroke.
The Bottom Line
It appears that a healthy diet and moderate alcohol consumption should maintain healthy arginine levels for most people.
"There are supplements that have medical benefits, but L-arginine is not one of them," Dasgupta says. "My recommendation is instead of spending the money on L-arginine, you can send the check to me."
Read more: The 10 Best Supplements
- Amitava Dasgupta, PhD, clinical toxicologist and professor, University of Texas Medical School, Houston
- Chest: “Exhaled Nitric Oxide Levels Among Adults With Excessive Alcohol Consumption”
- Food Chemistry: “Purification of Free Arginine From Chickpea (Cicer arietinum) Seeds”
- International Journal of Case Reports & Short Reviews: “Arginine Induced Metabolic Acidosis and Acute Kidney Injury”
- Jody Bergeron, RN, BSN, MS, CEN, nurse, Cape Cod Health Care, Mass.; guest blogger, American Society for Nutrition
- U.S. Department of Agriculture: “Dietary Guidelines for Americans, 2015-2020”
- U.S. National Library of Medicine: “L-Arginine”
- Yale School of Medicine: “Eating Nuts Q&A”