Researchers from the University of Toledo have analyzed 26 published studies, including a number of controlled clinical trials, in order to study the effect of several vitamin supplements on hospitalized COVID-19 patients. The findings indicate vitamin D, vitamin C and zinc supplements have no effect on mortality outcomes in severe COVID-19 cases.
The new study focused specifically on understanding whether there is a clinical benefit in giving certain vitamin supplements to people who are very sick with COVID-19. The study was not looking at whether pre-existing vitamin deficiency increases the severity of COVID-19 or whether taking supplements can prevent someone from being infected in the first place.
The systematic review looked at 10 studies reporting the results of controlled clinical trials and 16 observational studies. The final analysis included 5,633 hospitalized COVID-19 patients and the overall finding was that taking vitamin D, vitamin C or zinc supplements had no effect on a person’s risk of dying compared to sick patients not taking those supplements.
"A lot of people have this misconception that if you load up on zinc, vitamin D or vitamin C, it can help the clinical outcome of COVID-19," said lead author on the study Azizullah Beran. "That hasn't been shown to be true."
Looking more closely at the data the researchers found vitamin C and zinc supplements did nothing to benefit hospitalized COVID-19 patients compared to those not taking the supplements. However, there were small signals indicating vitamin D supplements may lower a patient’s risk of intubation and shorten their overall hospital stay.
The researchers are cautious to note there are discrepancies between studies on the benefits of vitamin D for treating severe COVID-19. Some trials have found no benefits from giving hospitalized COVID-19 patients vitamin D, while others have detected minor benefits. Beran and colleagues call for a larger more focused clinical trial to validate the influence of vitamin D on severe COVID-19 outcomes.
Although this new study focused on vitamin supplementation as a treatment for those already suffering from severe COVID-19 there is research looking at whether certain pre-existing vitamin deficiencies can influence the severity of disease. So far the results on this subject are mixed, with some studies finding a link between pre-infection vitamin D deficiency and increased disease severity and mortality, and others finding no association whatsoever.
The US National Institutes of Health (NIH) states there is insufficient evidence to recommend either for or against the use of vitamin D, vitamin C or zinc in the treatment of COVID-19. The NIH also warns excessive intake of zinc can lead to gastrointestinal harm.
Beran and colleagues are keen to point out their findings do not suggest people avoid vitamin supplements altogether, especially if they are deficient or malnourished. Instead, they say vitamin supplements should not be used as a replacement treatment for COVID-19 therapies with good evidence.
"What we're saying is this: If you don't medically need these supplements, don't take them thinking they're protective against COVID-19," said Beran. "They're not going to prevent you from getting it and they're not going to prevent you from dying."
The new study was published in the journal Clinical Nutrition Espen.
Source: University of Toledo
