Do vitamin D, zinc, and other supplements help prevent COVID-19 or hasten healing?
The appeal of safe and natural treatments is undeniable. This is true for age-old conditions such as the common cold and for new illnesses, especially if they have no known cure. So it makes sense that there is a lot of interest in supplements for COVID-19, whether for prevention or treatment.
Indeed, zinc, melatonin, vitamin C, vitamin D and other supplements are commonly prescribed from the first days of the pandemic.
But do they work?
Why Supplements Can Help Prevent or Treat COVID-19
While science can show whether a drug works, we may not always know why. When antibiotics were first discovered in the 1920s, understanding of the biology involved was limited. But failure to explain their benefits has not discouraged doctors from recommending these highly effective treatments.
While it is less clear whether a drug works, the biological plausibility – that is, a logical and well-understood reason why the drug should work – increases the expectation that he could.
So what is the suggestion that vitamin C, vitamin D, zinc, and melatonin might help fight any virus?
- Vitamin C is an antioxidant that has long been promoted as a key player in healthy immune function.
- Zinc may have antiviral activity, either by improving the function of immune cells that fight viral infections or by reducing the ability of viruses to multiply.
- Some evidence (see this study and this study) suggests that the combination of vitamin C and zinc may limit the duration and severity of cold symptoms.
The cases of vitamin D and melatonin differ. While there is also some evidence that vitamin D and melatonin may have positive effects on immune function, a specific antiviral effect remains to be proven.
What is the evidence that supplements are helpful for COVID-19?
Although COVID-19 is a new disease, a few clinical trials have explored the possibility that the supplements are effective. And, unfortunately, most of the evidence is not convincing.
For example, a few observational studies link lower blood levels of vitamins to a higher risk of testing positive for the virus that causes COVID-19 (see this study and this one). But studies like these can’t prove that vitamin D protects people from infections. Additionally, a randomized controlled study in people with moderate to severe COVID-19 who received a high dose of vitamin D showed no benefit.
Likewise, a 2021 study on zinc and vitamin C showed no benefit for people with mild COVID-19. In this study, people whose symptoms did not require hospitalization were randomized to receive
- vitamin C only, 8000 mg / day (the recommended daily dose is 75 mg / day for women and 90 mg / day for men)
- zinc only, 50 mg / day (the recommended daily dose is 8 mg / day for women, 11 mg / day for men)
- both supplements at the above doses
- no supplement.
The researchers found that people receiving the supplements, whether individual or in combination, had no improvement in symptoms or faster recovery compared to otherwise similar patients not receiving any supplements.
Supporters of melatonin for COVID-19 have encouraged researchers to conduct trials on this supplement, but so far convincing evidence of its benefits is not yet available.
Even without convincing evidence, why not take them anyway?
Despite questions about the overall benefit of these supplements, many doctors began to prescribe them routinely early in the COVID-19 pandemic. The logic, perhaps, has been that with so little knowledge of how best to deal with this new infection and a long history of safety for these supplements, why not?
But there are some important risks to consider. These include side effects, allergic reactions, interactions with other drugs, the cost of unnecessary supplements, and the dangers of consuming too much. For example:
- High doses of vitamin C can cause diarrhea or upset stomach. There are also concerns that high-dose vitamin C supplementation may interfere with anticoagulants or cholesterol-lowering drugs.
- High doses of vitamin D can cause serious symptoms, such as upset stomach, kidney damage, and pancreatitis, and can even be life threatening.
That said, people with nutritional deficiencies should receive supplements. Zinc or vitamin D deficiencies are not uncommon and can contribute to poor immune function. Therefore, even without specific evidence linking supplement use to improvement in people with COVID-19, these supplements may be appropriate for people in whom a deficiency is suspected or confirmed. For example, a person with little sun exposure and a diet low in dairy products may be susceptible to vitamin D deficiency. A simple blood test can confirm or rule out a vitamin D or zinc deficiency.
If you are taking supplements, it is safer to take the recommended daily amounts your body needs, unless your doctor tells you otherwise (see this information for people 51 years of age and older, and this information on a full range of supplements. ).
The bottom line
Based on science, there is reason to hope that supplements such as vitamin C or D, zinc or melatonin power helps fight COVID-19. While there is no evidence yet that they do, additional research may show benefit in certain situations, or with a different dose or formulation of the supplement. So it’s worth keeping an open mind.
In the meantime, we must not dismiss the results of negative studies simply because the results were not what we hoped for. When it comes to preventing or treating COVID-19, I would rely more on CDC recommendations than unproven supplements.
Check with your doctor before starting a supplement. Find out about the dosage, what other medicines you are taking, and what other health concerns you have. The last thing you want to do is take a supplement that causes more harm than good.
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The post Do Vitamin D, Zinc, and Other Supplements Help Prevent COVID-19 or Speed Healing? first appeared on the Harvard Health Blog.
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