The Claim

Three months of daily 4-gram L-citrulline supplementation reduces ICAM-1 levels by approximately 32.6 ng/mg of protein and increases six-minute walk test distance by 141.2 meters in adults recovering from severe COVID-19 who were hospitalized during acute infection.

Source: Effect of L-Citrulline Supplementation on Endothelial Function and Body Composition in Post-COVID-19 Syndrome: A Randomized Clinical Trial

What the research says

Supports is higher

Support is ahead, but a single strong opposing study can change this.

Supports
74score
Challenges
0score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

Quantitative
1 study reviewed
In plain English

In adults recovering from severe COVID-19 who were hospitalized, taking 4 grams of L-citrulline daily for three months lowers ICAM-1 protein levels by about 32.6 ng/mg and increases the distance walked in six minutes by about 141.2 meters.

See the scientific wording

Three months of daily 4-gram L-citrulline supplementation reduces ICAM-1 levels by approximately 32.6 ng/mg of protein and increases six-minute walk test distance by 141.2 meters in adults recovering from severe COVID-19 who were hospitalized during acute infection, suggesting a potential benefit for endothelial inflammation and aerobic capacity in this specific population.

Why this might work

L-citrulline is converted into L-arginine in the kidneys, which is used by blood vessel cells to make nitric oxide. Nitric oxide relaxes blood vessels, reduces inflammation in the lining of blood vessels, and lowers the amount of a protein called ICAM-1 that attracts immune cells. This improves blood flow to muscles during exercise, allowing more oxygen to reach them and enabling longer walking distance.

Verified mechanismbased on 1 study

What the research says

1 study

  1. Study: Effect of L-Citrulline Supplementation on Endothelial Function and Body Composition in Post-COVID-19 Syndrome: A Randomized Clinical Trial

    This study found that people who took 4 grams of L-citrulline every day for three months after being hospitalized with severe COVID-19 had less blood vessel inflammation and could walk 141 meters farther in six minutes than those who didn’t take it.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

Fit Body Science verdict — we translate health claims into clear verdicts backed by peer-reviewed research.

Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.