Dietary Supplements for COVID-19

  • End date
    Dec 14, 2022
  • participants needed
  • sponsor
    The Canadian College of Naturopathic Medicine
Updated on 14 March 2022


This is a double blind, placebo controlled, phase III randomized controlled trial evaluating the effects of the dietary supplements vitamin C, vitamin D, vitamin K, and zinc versus placebo on the overall health, symptom severity, and symptom duration of outpatients diagnosed with SARS-CoV-2.


This study proposed is a double-blind, placebo-controlled, phase III randomized controlled trial powered to detect meaningful differences in the overall health and symptom severity of people with COVID-19 between the treatment and control arms. Eligible participants will be randomly assigned, using a web randomization system, in a ratio of 1:1 to one of the following groups: (1) nutrient therapy with vitamin D, vitamin C, vitamin K2, and zinc or (2) placebo. Total trial duration will be 12 weeks. Nutrients or placebo will be given for a period of 21 days following enrolment and randomization. Total trial duration will be 12 weeks. Adverse events will be collected during the treatment phase plus one additional week (maximum 4 weeks).

With respect to the primary outcome of participant-reported overall health, power calculations were conducted based on between-group differences at a single time point (21 days) and Cohen's guideline for a small effect size of 0.3. A sample size of 176 (88 per arm) provides 80% power to detect a difference at an α of 0.05. To account for an approximate 10-15% lost to follow-up we will enrol 200 participants (100 per arm).

Condition Covid19
Treatment Vitamin D3 50,000 IU, Vitamin C/Zinc, Vitamin K2/D, Microcrystalline Cellulose Capsule, Medium Chain Triglyceride Oil
Clinical Study IdentifierNCT04780061
SponsorThe Canadian College of Naturopathic Medicine
Last Modified on14 March 2022


Yes No Not Sure

Inclusion Criteria

Adults (≥18) who test positive for SARS-CoV-2 in an outpatient setting
Access to internet

Exclusion Criteria

Symptom onset greater than 4 days prior to enrolment
Supplementing regularly with >500 mg vitamin C, >1000 units vitamin D, >120 mcg vitamin K (any form), or >15 mg zinc taken daily within the past month
Currently taking warfarin or an equivalent vitamin K antagonist anticoagulant
End stage chronic kidney disease
History of calcium oxalate kidney stones
Active granulomatosis (sarcoidosis, tuberculosis, lymphoma)
Known hypercalcemia or hypervitaminosis D
Currently taking either of the following antibiotics: cephalexin, tetracyclines
Participating in an investigational study or participation in an investigational study within the past 30 days
Any reason which, under the discretion of the qualified investigator or delegate, would preclude the patient from participating
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Additional screening procedures may be conducted by the study team before you can be confirmed eligible to participate.

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If you are confirmed eligible after full screening, you will be required to understand and sign the informed consent if you decide to enroll in the study. Once enrolled you may be asked to make scheduled visits over a period of time.

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