Arginine plus vitamin C supplementation for long COVID Original paper

Long COVID is characterized by the persistence of symptoms after an acute COVID-19 episode and is associated with fatigue and reduced physical performance. Symptoms of impaired vascular function, such as dizziness when standing, have also been reported.^[1]

Supplemental L-arginine has been credited with supporting vascular health and improving endothelial function via stimulation of nitric oxide synthesis. Research was needed to determine whether supplementation with L-arginine can aid recovery from long COVID.

This single-blind randomized controlled trial included 46 participants (median age of 50; 65% women, 35% men) who were experiencing persistent fatigue after COVID-19. The participants received either a placebo or a combination of 1.7 grams of L-arginine plus 500 mg of liposomal vitamin C to be taken twice daily for 28 days.

The primary outcome was the distance walked in the 6-minute test. Handgrip strength and reported fatigue were also tracked, along with flow-mediated dilation (a noninvasive measure of endothelial function based on arterial dilation).

Supplementation with L-arginine + vitamin C improved walking performance and muscle strength compared to placebo. Endothelial function was also greater in the supplement group compared to the placebo group. At 28 days, 21 participants in the placebo group reported persistent fatigue, compared to only 2 participants in the supplement group.

Although this trial was not sized to detect sex-based differences, the treatment effects were more evident in female participants than in male participants.

The authors of this trial concluded that although more research is needed, these preliminary results suggest that a combination of L-arginine and vitamin C may restore physical performance and relieve persistent symptoms in people with long COVID.

A single-blind design was selected to maximize participant safety in the absence of a safety monitoring board. All outcome measures were assessed by investigators who were blinded to participant group assignment.