
Since the beginning of the COVID-19 pandemic, there has been much interest in which vitamins and supplements might help guard against coronavirus, and very little data. But a new study by the COVID Tracking Project has shed light on which supplements may be protective against COVID-19—although it comes with some caveats. Researchers asked 1.4 million people using the ZOE Covid Symptom Study app which supplements they had used, and their COVID status history. These vitamins and supplements have "small protective effect," claims the study—read on, and to ensure your health and the health of others, don't miss these Sure Signs You've Already Had Coronavirus.
Multivitamins

"Taking a multivitamin may increase daily quality of life through increased energy, often from the B vitamin combinations, along with other protective measures," says Dr. Danielle Plummer, PharmD. However, "It's important to choose a vitamin that has the nutrients in which you are deficient and meets your nutritional needs," she warns.
Vitamin D

"Low levels of vitamin D may put people at risk for developing COVID-19, according to a new study by Leumit Health Care Services and Bar-Ilan University's Azrieli Faculty of Medicine," reports the Jerusalem Post. "The main finding of our study was the significant association of low plasma vitamin D level with the likelihood of COVID-19 infection among patients who were tested for COVID-19," say researchers. "Furthermore, low vitamin D level was associated with the risk of hospitalization due to COVID-19 infection."
Omega-3

"Have you considered taking an omega-3 supplement?" asks Dr. Deborah Lee. "These are polyunsaturated fatty acids, which have been found to be vital for many cell-signaling and repair mechanisms in the body. They have a hugely important role in immune function, blood clotting and have strong anti-inflammatory effects. Reduced levels of omega-3 have been found in people with dementia. Although not conclusive, studies suggest increasing intake of omega-3 may help protect you."
Probiotic Supplements

"Supplementing daily with a high-quality probiotic can help strengthen your immune system, ease digestive issues, decrease overall inflammation and help with regularity," says Danielle Omar, MS, RD, Integrative Dietitian. "A form of 'good' bacteria, probiotics work to restore a healthy balance of microflora in the body by decreasing the 'bad' inflammatory bacteria in our guts, and replacing the 'friendly' bacteria that are often destroyed, like when we take antibiotics."
On the Other Hand, Researchers "Saw No Protective Effect" From The Following

Supplements such as vitamin C, garlic, and zinc have no correlation to a lower amount of COVID-19, according to the study.
The Researchers Note This Research is Still Speculative

"Our research is an observational study and not a clinical trial, so it is quite speculative, and we can't make strong recommendations based on the data we have," said lead researcher Dr. Cristina Menni. She said that because the study relied on people's self-reporting of supplement usage, those results could be imprecise.
"We need large randomized controlled clinical trials to determine whether supplements have a real effect on COVID risk, and several studies investigating the effect of vitamin D are underway. Until we have further evidence about the role of supplements in COVID prevention, we recommend following NHS guidance on vitamins usage, as part of a healthy balanced diet," she added.
There May Be a Few Biases at Play

Another caveat: The researchers found that multivitamins, vitamin D, omega 3, and probiotic supplements all seemed to modestly protect women, but not men. That could be because of immune system differences between men and women, or reporting bias (women being more likely to report supplements they're taking). The truth is unclear.
Another significant question: does the correlation reflect a "healthy bias," meaning that people who take supplements are more likely to follow public-health measures that can reduce coronavirus transmission, such as handwashing and social distancing?
"If our results were only a reflection of the healthy bias effect, we would expect to see an effect from all the supplements we looked at, but we only see a protective effect from multivitamins, vitamin D, omega-3 and probiotics," said Menni.
"What's more, we adjusted our data to account for lots of potentially confounding factors that may reflect the 'healthy bias' like smoking, healthcare status, diet, income, BMI, age and underlying health conditions, and the correlation remained significant," she said.
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So How Do You Keep Your Immune System Strong Against COVID?

So does this mean you should stock up on supplements to avoid getting COVID-19? Dr. Anthony Fauci, the nation's leading infectious disease expert, says there's good evidence for some supplementation, and not for others. "There is good evidence that if you have a low vitamin D level, that you have more of a propensity to get infected when there are infections around," he said last fall. "Those data are pretty good data." Fauci has said he takes vitamin D and vitamin C supplements.
However: "If you really want to keep your immune system working optimally, there are things that you do that are normal things: get a reasonable amount of sleep, get a good diet, try to avoid or alleviate severe stress, which we know can sometimes impact the immune system," said Fauci. "That is much more healthy living than giving yourself supplements of anything."
And do everything you can to prevent getting—and spreading—COVID-19 in the first place: Wear a face mask, get tested if you think you have coronavirus, avoid crowds (and bars, and house parties), practice social distancing, only run essential errands, wash your hands regularly, disinfect frequently touched surfaces, and to get through this pandemic at your healthiest, don't miss these 35 Places You're Most Likely to Catch COVID.