For decades L-arginine has been used in nutritional supplement blends to support muscle growth, heart health and erectile dysfunction. Now a new study has examined L-arginine with regards to a new medical condition—Long Covid.

In the study, conducted in Italy, researchers found a supplement blend of L-arginine and Vitamin C was able to “relieve persistent symptoms of Long Covid.”

Long Covid or “Long-haul Covid” is a condition where long-term health problems persist after the typical recovery period of Covid-19.

L-arginine… amino acid extraordinaire!

L-arginine is an amino acid that helps the body build protein. A healthy, young human body typically receives all the L-arginine it needs through diet and synthesis. It is either acquired by consumption of protein-rich foods, or it is synthesized in the body from other amino acids (glutamine and citrulline).

Aging and other circumstances can cause a person to have sub-optimal levels of L-arginine—poor diet, injury, illness, stress and some medications.

L-arginine was first isolated in 1886 from yellow lupin seedlings by the German chemist Ernst Schulze and his assistant Ernst Steiger. Schulze was also part of the team that had isolated the amino acid L-glutamine from sugarbeets three years earlier.

L-arginine plays an important role in cell division, wound healing, removing ammonia from the body, immune function, and release of hormones. It is a precursor for the synthesis of nitric oxide, making it important in the regulation of blood pressure.

As an important immune nutrient, L-arginine is also necessary for T-Cells to function in the body.

The Cleveland Clinic states, “L-arginine is semi-essential or conditional, which means that your body can produce the amino acid, but you also need to include some sources of the amino acid in your diet. You can also take L-arginine as a supplement by mouth.”

Mayo Clinic adds, “Because L-arginine acts as a vasodilator, opening blood vessels, many people take oral L-arginine to treat heart conditions and erectile dysfunction.”

The Cleveland Clinic and Mayo Clinic websites list similar conditions they say are eligible for treatment with L-arginine: Angina, high blood pressure, preeclampsia, erectile dysfunction, peripheral arterial disease and migraines.

New study

In the new Italian study researchers found patients who were provided a supplement blend of L-arginine and Vitamin C showed “clinically meaningful improvements” in distance walking, enhanced handgrip strength and reduced fatigue.

The placebo-controlled trial was performed at a post-acute Covid-19 outpatient clinic in Rome, Italy and included 46 participants. The test subject-patients were treated for a period of four to eight weeks.

What does the “L” in L-arginine stand for?

The letter L in front of arginine stands for “levorotatory,” which is a chemistry term that means the amino acid didn’t bond with a protein molecule (free form).

This helps providers categorize amino acids based on how similar they are to the amino acids humans produce in their own bodies.

The L designates that it easily absorbs into your body because it’s most similar to amino acids already in your body.

Participants had previously been infected with SARS-CoV-2, had received a Long Covid diagnosis, and suffered from persistent fatigue. Serum L-arginine levels were measured prior to the trial and at 28 days.

At the end of eight weeks researchers reported measureable improvements in both aerobic and anaerobic performance. Treatment induced greater improvements in handgrip strength, and 80% of participants reporting reduced fatigue—the most prevalent symptom in Long Covid.

“A short-term oral administration of L-arginine significantly decreased the mean pulmonary arterial pressure and vascular resistance and improved peak oxygen consumption and dead-space ventilation in patients with precapillary pulmonary hypertension,” the researchers wrote in the study findings.

The study was published in Nutrients in November 2022.

Though the study broke new ground in that it examined L-arginine as it relates to Long Covid, it is certainly not the first examination of L-arginine in supporting the original Covid-19 illness.

A review published in Nutrients a year earlier, in November 2021, concluded L-arginine was an effective therapeutic in treating Covid-19 patients.

“There is a strong rationale indicating a beneficial effect of L-arginine in Covid-19, and preliminary results from the randomized clinical trial seem to support this view,” the researchers wrote in the study summary.

Optimal Health Systems offers L-arginine in two of its blends:

Optimal Opti-T
NOS Performance Paks

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Sources: Nutrients (Nov. 2022 Italian Long Covid study), Nutrients (Nov. 2021 Covid therapeutics study).