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Vitamin C and zinc Covid study was “destined to fail” campaigners and industry groups claim

A recent study showing that zinc and vitamin C are not effective treatments for COVID-19 was “destined to fail” and “plagued by weak design”, natural health campaigners and industry groups have claimed. 

In a small study by Cleveland Clinic, 214 adult patients with a confirmed COVID-19 infection were randomized and either received 10 days of zinc gluconate (50 mg), vitamin C (8000 mg), a combination of both micronutrients, or standard care.

The study, published in the JAMA Open Network, was halted when no significant difference among the four groups could be identified, leaving the researchers to conclude that “zinc or ascorbic acid (vitamin C) – or a combination of the two – do not significantly decrease the severity or duration of symptoms in COVID-19-positive patients, when compared to standard care”. 

“Destined to fail”
But the Cleveland study has been roundly criticised by natural health campaigners and industry groups. Alliance for Natural Health International claims the study was “destined to fail”. In a commentary, ANH’s scientific director, Dr Robert Verkerk, says the study’s failure was: “predictable as the nutritional treatments started too late – only after symptoms of disease were being expressed, which may have been between 4 and 12 days after the study participants became infected”. Verkerk adds that the “treatments were also inadequate because the vitamin C dose was too low, and they failed to include another key nutrient, pro-hormone and immune system modulator, vitamin D”. 

“Oral nutritional supplements like vitamin C and zinc, as well as vitamin D, are all about prevention”

More fundamentally, says ANH, the Cleveland team made an error in studying vitamin C and zinc’s effectiveness as treatments for Covid patients. Verkerk writes: “Oral nutritional supplements like vitamin C and zinc, as well as vitamin D, are all about prevention… So if the trial was really to look at prevention, much more meaningful results would have been gained if the subjects in the supplement arms were already taking vitamin C and zinc for at least 2 weeks prior to symptoms being tracked. In the case of vitamin D, it would be around 3 months”. 

“Plagued by weak design”
In the US the Council for Responsible Nutrition said the Cleveland study was “plagued by weak trial design” and “provided little insights into understanding the appropriate role of these nutrients”. 

CRN president and CEO, Steve Mister, said in a statement:  “Publication of this study and the accompanying commentary does nothing to advance our understanding of the role of nutrients in reducing the risk of COVID-19 and provides little insight for treating the disease. The study is plagued by a poor, open-label design, insufficient number of participants, substantial differences in the health status of participants by group, and the expectation that essential nutrients should behave like high-powered pharmaceuticals. 

“Publication of this study and the accompanying commentary does nothing to advance our understanding of the role of nutrients in reducing the risk of COVID-19 and provides little insight for treating the disease.”

“It’s not surprising this weak study design and haphazard approach would lead to unclear results. What’s more disappointing is that JAMA published it at all and accompanied it with a commentary that recklessly makes broad generalizations about the role of dietary supplements in the prevention and treatment of COVID-19. The sleight of hand potentially deters future research that may demonstrate the valuable role nutrients play in supporting immune function over time and preventing COVID-19 in particular. 

Meanwhile Todd Runestad, a senior editor at New Hope Network, took aim at an accompanying commentary on the Cleveland Study (also published in JAMA) by two doctors at John Hopkins University, which used the findings of the trial to launch an attack on the vitamin industry. “Just another salvo in a greater campaign to discredit supplements, with the implicit conspiratorial theory that pharmaceutical drugs are the only way to improve lives,” concluded Runestad.

Photo by Diana Polekhina on Unsplash

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