Dietary supplements to reduce symptom severity and duration in people with SARS-CoV-2: a double-blind randomised controlled trial
Dugald Seely, Mark Legacy, Ellen Conte, Caitlyn Keates, Athanasios Psihogios, Tim Ramsay, Dean A Fergusson, Salmaan Kanji, John-Graydon Simmons, Kumanan Wilson
BMJ Open, doi:10.1136/bmjopen-2023-073761
Background COVID-19 has caused morbidity, hospitalisation and mortality worldwide. Despite effective vaccines, there is still a need for effective treatments, especially for people in the community. Dietary supplements have long been used to treat respiratory infections, and preliminary evidence indicates some may be effective in people with COVID-19. We sought to evaluate whether a combination of vitamin C, vitamin D 3 , vitamin K 2 and zinc could improve overall health and decrease symptom burden in outpatients diagnosed with COVID-19. Methods Participants were randomised to receive either vitamin C (6 g), vitamin D 3 (1000 units), vitamin K 2 (240 μg) and zinc acetate (75 mg) or placebo daily for 21 days and were followed for 12 weeks. An additional loading dose of 50 000 units vitamin D 3 (or placebo) was given on day one. The primary outcome was participant-reported overall health using the EuroQol Visual Assessment Scale summed over 21 days. Secondary outcomes included health status, symptom severity, symptom duration, delayed return to usual health, frequency of hospitalisation and mortality. Results 90 patients (46 control, 44 treatment) were randomised. The study was stopped prematurely due to insufficient capacity for recruitment. The mean difference (control-treatment) in cumulative overall health was -37.4 (95% CI -157.2 to 82.3), p=0.53 on a scale of 0-2100. No clinically or statistically significant differences were seen in any secondary outcomes. Interpretation In this double-blind, placebo-controlled, randomised trial of outpatients diagnosed with COVID-19, the dietary supplements vitamin C, vitamin D 3 , vitamin K 2 and zinc acetate showed no clinically or statistically significant effects on the documented measures of health compared with a placebo when given for 21 days. Termination due to feasibility limited our ability to demonstrate the efficacy of these supplements for COVID-19. Further research is needed to determine clinical utility. Trial registration number NCT04780061.
Competing interests None declared. Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Patient consent for publication Not applicable. Ethics approval This study involves human participants and this study was approved by the Research Ethics Boards of the Ottawa Health Sciences Network (20210072-01H) and Canadian College of Naturopathic Medicine (CCNMREB036. Seely.Wilson). No study activities took place before approval by both organisations. Each participant signed an informed consent form approved by both organisations prior to participation in the study. Participants gave informed consent to participate in the study before taking part. Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available on reasonable request. Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages),..
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