A new systematic review authored by researchers from Greece examines the prognostic role of micronutrient status and dietary supplement use in COVID-19 outcomes. Finding that micronutrient deficiency on admission to hospital is related to a high risk of admission to an intensive care unit (ICU), intubation, and death, the review specifically highlights the importance of ensuring a healthy micronutrient status and notes that supplements may make a significant difference to patient outcomes.
Published in the Food and Chemical Toxicology journal, the review looks at 31 studies (27 observational studies and 4 clinical trials) involving a total of 8,624 patients. The average age of the patients was 61. Fourteen of the studies focused on vitamin D, 12 on calcium, 4 on zinc, 4 on magnesium, 3 on phosphorus, 2 on vitamin C, 2 on selenium, and 2 on folate. Other micronutrients studied included iron, vitamin B12, vitamin E, melatonin, and N-acetylcysteine.
The researchers write that most human studies on COVID-19 patients agree that having vitamin D levels within normal limits on admission to hospital may assist in a favorable outcome. They say this finding strengthens the hypotheses that vitamin D acts both as an immune booster and an antiviral agent.
Along with vitamin D, the researchers state that calcium is currently the most studied molecule among critically ill COVID-19 patients. Noting that, even prior to the COVID-19 outbreak, low blood levels of calcium were already a known abnormality accompanying multiple viral infections, they say their results indicate that normal calcium levels act protectively and are related to survival.
Turning to zinc, the researchers describe how a deficiency of this mineral disturbs the development of immune cells and that, in clinical practice, has been related both to viral infections and severe pneumonia among the elderly. They add that zinc supplements have been shown to be effective in recovery from the common cold. Noting the clinical improvement of COVID-19 patients with normal zinc levels compared to those deficient in the mineral, they say zinc supplements show promise as a treatment for COVID-19.
The researchers also write positively about selenium, which they describe as a crucial biomarker for the prognosis of multiple viral infections including influenza, coxsackie virus, cytomegalovirus, and hepatitis C. They additionally note that low selenium levels have been related to high pathogenicity of influenza and suppressed immune response, and refer to the negative role of selenium deficiency in COVID-19 patients.
On the downside, while they acknowledge that other recent reviews agree that micronutrients play a crucial role in COVID-19 progression, prognosis, and survival, the researchers claim that findings from human studies and clinical trials for vitamin C and other antioxidants are unclear. In reality, of course, this is hardly the case.
Not only has high-dose vitamin C has been clinically used for several decades, a placebo-controlled clinical study conducted in China in 2020 documented that it greatly reduces mortality in patients at life-threatening stages of COVID-19. Last year, building on this finding, a review of 12 studies, including 5 randomized controlled trials, provided still further confirmation that vitamin C is effective at treating COVID-19. The authors found clear evidence that intravenous vitamin C may improve oxygenation parameters, reduce inflammatory markers, decrease days in hospital, and reduce mortality.
Ultimately, therefore, while the Greek Food and Chemical Toxicology journal researchers are of course right to say that more research is needed, the fact is that in every scientific field more research is always needed. At some point, however, in the field of medicine, the level of evidence supporting a treatment’s efficacy and safety reaches the point where the time has come to implement it into clinical practice. In the case of nutritional and Cellular Medicine approaches to COVID-19, that time is now.