A: Here is the best evidence we found.
Vitamin C: No. Modest evidence in prevention (even for the common cold). Evidence for treatment is still being examined in COVID-19 but unlikely to yield much benefit. May reduce ICU stay length and decrease need for mechanical ventilation but still being studied.
Vitamin D: Yes to daily recommended doses. Some observational studies have pointed to the association between low Vitamin D levels and cold seasons. Early studies are coming out showing association between severity of illness in COVID-19 and low Vitamin D levels. Still, we don’t know the relationship yet. Adults are recommended to take standard daily doses of approximately 1000IU to 2000IU daily.
Zinc: Maybe. There is moderate evidence for use of Zinc in shortening the duration of the common cold and decreasing incidence of respiratory infections. Adults may take zinc to prevent common colds but there is no evidence that it prevents COVID-19. If taken, limit to daily recommended dose of 8mg for women and 11mg for men.
Elderberry: No. There is modest evidence in lab studies of modulation of inflammation. However, there are no gold standard clinical trials and limited evidence in COVID-19.
Silver: NO. Issued a warning by the FDA for harmful side effects. Proposed properties do not outweigh benefits and risks.
In sum, it can’t hurt to take a multivitamin and a daily dose of Vitamin D (1000-2000IU maximum). Everything else (especially in higher than daily dose recommendations) is not recommended by the experts.
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