Tier 2 — strong

Effects of nicotinamide riboside on NAD+ levels, cognition, and symptom recovery in long-COVID: a randomized controlled trial

Wu CY, Reynolds WC, Abril I, McManus AJ, Brenner C, González-Irizarry G, Gutiérrez-Martínez L, Sun O, Rosand J, Tanzi RE, Arnold SE, Guzmán-Vélez E
EClinicalMedicine 2025 89; 103633

Bibliography

PubMed
PMID 41357333
PubMed Central
PMC12675013
DOI
10.1016/j.eclinm.2025.103633
Funding
Niagen Bioscience, Massachusetts General Hospital research funds and Alzheimer’s Association support.
Competing interests
Two authors disclosed Niagen Bioscience scientific-advisory roles and equity; additional pharmaceutical research and consulting relationships were reported.

Study snapshot

DesignRandomized placebo-controlled human trial
ModelHuman participants
Sample58 adults with long COVID; 37 NR-NR and 21 placebo-NR
InterventionNR 2000 mg/day with placebo lead-in and delayed-start comparison
Duration24-week protocol; up to 20 weeks of active NR
EndpointsCognition; fatigue; sleep and mood

What the study showed, in plain terms

NR increased blood NAD+ but did not improve cognition, fatigue, sleep or mood versus placebo.

Key findings

NR increased blood NAD+ but did not improve cognition, fatigue, sleep or mood versus placebo.

What this study can and cannot tell us

Substantial differential dropout and exploratory, unadjusted within-group analyses limit favorable symptom interpretations; those analyses do not replace the randomized comparison.

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Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction Dr. Amr Yasser, PhDCardiometabolic, Musculoskeletal, Gut & Bioavailability Dr. Abdulla Mostafa, PhDCellular Senescence, Neurological, Mitochondrial & Brain-Ageing Biology