Analysis: there's no specific food guaranteed to protect you from the coronavirus so general healthy eating guidelines are the best advice for now

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Dr Oz has been all over US network television this week advising on strategies to avoid getting the coronavirus and also on how to treat the virus. The nutrition aspect of his "survival guide" talks about the benefits of vitamin D supplements, eating fruit and veg to protect yourself and consuming elderberry syrup four times a day for five days to treat the viral infection. If only it were that simple!

Thankfully, Oz is not heading up the national response to containing the coronavirus in Ireland. In the words of Jürgen Klopp, "people with knowledge will talk about it. I wear a baseball cap and have a bad shave. My opinion is really not important."

But is there any truth at all in the claims from Oz? The former Oprah Winfrey protégé has a history of doling out scientifically dubious claims, so let’s see if there is anything worth taking from his survival guide. Washing your hands, maintaining social distancing, avoiding touching your mouth or nose, appropriate cough and sneeze etiquette as well as practicing good food hygiene are all accepted as sound advice with good evidence in support of these recommendations. The WHO also advise on adopting good sleep, activity and dietary practices, if you feel stressed during the outbreak.

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But they do not advocate elderberry syrup. It is implicit in the WHO advice that optimal lifestyle practices (sleep, activity and diet) can support health and may prevent ill health. However, the bottom line is that there is no magic pill or a specific food guaranteed to bolster your immune system and protect you from the coronavirus.

Nevertheless, there are real ways you can take care of yourself and give your immune system the best chance to do its job against any respiratory illness.  A healthful diet is important to maintain a functioning immune system. However, no single food or natural remedy has been proven to ward off disease.

For many years, high dose vitamin C consumption has been part of cultural practice when suffering with a cold or flu. This is due to a book published by Nobel prize winner Linus Pauling theorising on how vitamin C helps treat colds.

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In the following few decades, multiple randomized controlled studies examined whether the vitamin had any effect on the common cold. The results have been disappointing. An analysis of 29 studies including 11,306 participants concluded that supplementing with 200 mg or more of vitamin C did not reduce the risk of catching a cold. However, regular vitamin C supplements had several benefits, including reduced cold severity and duration. Supplements decreased recovery time by 8% in adults and 14% in children, on average. A supplemental dose of 1–2 grams was enough to shorten the duration of a cold by 18% in children, on average.

Zinc supplements and lozenges are another popular remedy for fighting off colds and respiratory illness. Some studies have found that zinc lozenges may reduce the duration of cold by about a day and may reduce the number of upper respiratory infections in children. However, the data on zinc are mixed.

The data on vitamin D and immune function is also equivocal. Vitamin D, often referred to as the sunshine vitamin. is found in fatty fish, such as salmon, and in milk or foods fortified with vitamin D. A more recent analysis of 25 randomized controlled trials of 11,000 patients showed an overall protective effect of vitamin D supplementation against acute respiratory tract infections. The research is not conclusive, and some studies of vitamin D have not shown a benefit.

A healthful diet is important to maintain a functioning immune system, but no single food or natural remedy has been proven to ward off disease.

It has long been know that an individual’s nutritional status can influence their susceptibility to and their response to infection. Adherence to general healthy eating guidelines, and consuming adequate fluids seems like the best advice for now.  The last word should go to Hippocrates, the founder of the concept of food as medicine: "if we could give every individual the right amount of nourishment and exercise, not too little and not too much, we would have found the safest way to health."


The views expressed here are those of the author and do not represent or reflect the views of RTÉ