Arginine & Vitamin C for Long COVID: Does it Help?

randomized-controlled-trial PMID: 36501014

Quick Summary: A recent study found that taking l-arginine and vitamin C supplements together may help people with long COVID feel less tired and improve their physical abilities, like walking and grip strength.

Can Arginine Help Long COVID Symptoms?

This research looked at whether a combination of l-arginine and vitamin C could help people struggling with long COVID. The study found that taking these supplements for a month improved:

Walking distance: People could walk further in six minutes.

Muscle strength: Grip strength improved.

Blood vessel function: Improved blood flow.

Fatigue: Fewer people reported feeling tired.

What The Research Found

The study showed that taking l-arginine and vitamin C together for 28 days led to:

Better Walking: People walked an average of 30 meters further in six minutes.

Stronger Grip: Handgrip strength increased by about 3.4 kg.

Improved Blood Flow: Blood vessel function improved.

Less Fatigue: Only a small number of people in the supplement group felt tired, compared to the placebo group.

Study Details

Who was studied: Adults aged 20-60 who had long COVID and were experiencing fatigue.

How long: The study lasted for 28 days (about a month).

What they took: Participants took either:

l-arginine (1.66 grams) and vitamin C (500 mg) twice a day.
A placebo (a pill with no active ingredients) twice a day.

What This Means For You

If you have long COVID and are experiencing fatigue, this research suggests that taking l-arginine and vitamin C might help you:

Feel less tired.

Improve your physical performance.

Boost your muscle strength.

Important: Talk to your doctor before starting any new supplements. They can help you decide if this is right for you and make sure it won't interfere with any other medications you're taking.

Study Limitations

It's important to remember:

Small Study: The study only included a small number of people, so more research is needed.

Short Time: The study only lasted a month, so we don't know the long-term effects.

Combination: The study looked at the combination of l-arginine and vitamin C, so we don't know if one works better than the other.

Single-Blind: Participants knew if they were taking the supplement or the placebo, which could have influenced the results.

Key Findings

The study found that daily supplementation with l-arginine (1.66 g twice daily) plus liposomal vitamin C (500 mg twice daily) for 28 days significantly improved physical performance, muscle strength, endothelial function, and fatigue in adults with long COVID. Key results included:
- +30 meters walked in the 6-minute walk test (p = 0.001).
- +3.4 kg improvement in handgrip strength (p = 0.03).
- 14.3% flow-mediated dilation (FMD) vs. 9.4% in placebo (p = 0.03).
- Only 8.7% of participants reported fatigue vs. 80.1% in placebo (p < 0.0001).

Study Design

Type: Single-blind, randomized, placebo-controlled trial.
Population: Adults aged 20–60 with persistent fatigue post-COVID-19, recruited from a post-acute outpatient clinic.
Sample Size: 50 participants randomized (23 in active group, 23 in placebo group completed the trial).
Duration: 28 days of supplementation.
Allocation: 1:1 ratio to either l-arginine + vitamin C or placebo.

Dosage & Administration

Intervention:
l-arginine: 1.66 g orally, twice daily.
Vitamin C: 500 mg liposomal formulation orally, twice daily.
Placebo: Identical administration schedule with inert substances.
Timing: Supplementation period lasted 28 days.

Results & Efficacy

6-Minute Walk Test: Active group increased distance by 30 m (SD 40.5), while placebo showed no change (0 m, SD 75; p = 0.001).
Handgrip Strength: Active group improved by +3.4 kg (SD 7.5) vs. +1 kg (SD 6.6) in placebo (p = 0.03).
Flow-Mediated Dilation (FMD): Active group achieved 14.3% FMD (SD 7.3) vs. 9.4% (SD 5.8) in placebo (p = 0.03).
Fatigue Persistence: At day 28, 2/23 (8.7%) in the active group reported fatigue vs. 21/26 (80.1%) in placebo (p < 0.0001).
Statistical Significance: All primary and secondary outcomes met significance thresholds (p < 0.05).

Limitations

Single-Blind Design: Participants knew their treatment group, risking placebo effects or bias.
Small Sample Size: Only 46 completers (23 per group), limiting generalizability.
Short Duration: Effects observed over 28 days; long-term efficacy/safety unknown.
Combination Effect: Results reflect the combined intervention, not individual contributions of l-arginine or vitamin C.
Demographics: 65% women, median age 51 (IQR 14), potentially skewing results toward middle-aged women.

Clinical Relevance

For adults with long COVID experiencing persistent fatigue, this study suggests that l-arginine + vitamin C may offer measurable benefits in physical performance, vascular health, and fatigue reduction. However, the findings should be interpreted cautiously due to the small sample size and short duration. Clinicians might consider this combination as an adjunct therapy while monitoring individual responses. Supplement users should consult healthcare providers before use, particularly given the liposomal vitamin C formulation and lack of data on standalone l-arginine effects. Further research is needed to validate these results in larger, more diverse populations.

Source: PubMed - 2022