Red beetroot juice may have positive effects on multiple pathways involved in long COVID. The aim of this pilot study was to explore the impact of beetroot juice supplementation on physical function, gut microbiota, and systemic inflammation in adults with long-COVID

A single-center, double-blind, placebo-controlled randomized trial to test the effects of 14 days of beetroot juice supplementation on functional and biological outcomes in adults with long-COVID.

Participants were randomized 1:1 to receive either daily oral supplementation with 200 mL beetroot juice or placebo for 14 days. The primary endpoint was the change from baseline to day 14 in the fatigue resistance test. Secondary outcomes included the distance walked on the 6-min walk test, handgrip strength, and flow-mediated dilation. Secondary endpoints also included changes from baseline in circulating inflammatory mediators, metagenomic and fecal water metabolomic profiles. Partial least squares discriminant analysis (PLS-DA) models were built to evaluate the differences in biological variables associated with the interventions.

Inclusion Criteria:

• a certification of a previous SARS-CoV-2 infection
• a negative COVID-19 swab test at least four weeks prior to the screening visit
• meet the criteria for long-COVID diagnosis according to the World Health Organization criteria
• report persistent fatigue

Exclusion Criteria:

• intolerance to beetroot juice or its derivatives
• clinical conditions and/or use of medications that may interfere with trial outcomes (e.g., pregnancy or breastfeeding, diabetes, use of steroids or non-steroidal anti-inflammatory drugs, immunosuppressants, nitrates)
• participation in other intervention trials for long-COVID