Can vitamin supplements boost immunity against coronavirus? Which vitamins can I take to avoid or fight COVID-19?‍

We all know that vitamins and minerals are vital for our immune systems. But which vitamins should you take to boost your immunity against the novel coronavirus? Is there any evidence that these supplements work? And even if they don't, what's the harm? 

We spoke to ZOE co-founder Professor Tim Spector, author of the book 'The Diet Myth,' to find out. ‍

Do vitamins play a role in immunity?‍

The novel coronavirus is sweeping the world, and as a result, everyone is searching for ways to protect themselves and their loved ones. Many people have been buying supplements and vitamins, particularly so-called ‘immune-boosting’ supplements, to try and stay healthy.‍

Vitamins play a central role in helping our immune systems protect against infection and fight disease. Vitamins A, C, E, and B6 all support healthy, normal immune responses to pathogens like viruses, as do minerals like folic acid, zinc, selenium, iron, and copper. 

Deficiencies of these nutrients can leave us more susceptible to infections or less able to shake off illness. 

So, should we all be taking supplements to make sure we’re getting enough of these vital vitamins to keep our immune systems working properly?  ‍

It’s important to note that people with medically diagnosed vitamin deficiencies can benefit from appropriate supplements prescribed by a registered professional such as a GP or dietitian. ‍

For example, the NHS currently recommends vitamin D for breast-fed babies, and vitamin A, C and D for children under 5, especially those who don’t eat a varied diet. 

As for most of the rest of the population? Unfortunately, vitamin supplements aren’t the easy immunity solution that they might seem. ‍

Can vitamin supplements boost the immune system?

“The evidence in the scientific literature to support vitamin supplements is pretty dreadful,” says Tim. “I would say there's absolutely no data to support most of them, with only two or three possible exceptions.”

“One exception would be zinc," he explains, "but that data which allows any supplement with a trace of zinc to make health claims is about 20 or 30 years old and hasn't been updated so it could be flawed.” 

Indeed, recent studies have failed to prove that taking zinc supplements can decrease your risk of catching respiratory infections.

“There was also one report about vitamin D with a summary of a few bad studies to show it could help the immune system,” adds Tim. “But these are mostly observational studies and rigorous vitamin D supplementation trials for various conditions have proven that it’s not helpful.” 

What’s more, several studies have shown that vitamin D supplementation does not reduce rates of colds and flu. It also did not lower the risk of catching swine flu (H1N1) during the 2009-10 epidemic. In fact, looking at it the other way around, low vitamin D may just be a marker of being less healthy.

"People often ask about vitamin C too," says Tim. "All the meta-analyses of the trials about vitamin C have shown that it doesn't prevent any infections.”

He adds, “There's some evidence that if you take large amounts just as you get a common cold, you can reduce the symptoms by about half a day. But you have to time it perfectly.”

So, the evidence for vitamin supplements is pretty sketchy. The truth is, most of them don't work for most people. Many of them aren’t absorbed well by the body, while others just end up giving you expensive urine. ‍

What’s the harm?‍

“Vitamins are by definition needed in minute amounts, but in large doses can be very bad for you,” Tim explains. “There's probably more people dying because of taking vitamin supplements than are ever saved by them. The body is used to small, steady amounts of vitamins and minerals in food, and isn’t used to taking in large amounts of pure vitamin chemicals.”

For example, vitamin D overdoses can have serious medical consequences, while taking beta carotene, vitamin E, and high doses of vitamin A have been shown to increase death rates. 

It’s also important to remember that many vitamins and other supplements can interfere with any medication you may be taking and reduce its effectiveness. 

For example, taking calcium or magnesium as a supplement can reduce the effect of a range of drugs from aspirin to some antibiotics and anti-retroviral drugs, which could have substantial knock-on effects on your health.‍

What is the best way to support my immune system to fight COVID-19?‍

The answer is simple, although much less alluring than the pricey supplement concoctions advertised online. 

"Get a balanced diet, with plenty of diversity of plants, fruits, and vegetables,” says Tim. “That will give you all the vitamins and minerals you need.”

And as a bonus, a healthy diet with lots of different plants will also help keep your gut microbes happy. 

“That's the most certain way you can maximize your immune system,” says Tim. “A healthy microbiome is likely to support your immune system and in turn - whilst no guarantee - will increase your chances of staying healthy too.”‍

The summary on supplements:

• Vitamins and minerals are essential to support healthy immune system function
• The best way to support your immune system is to eat a healthy, varied diet
• Talk to your doctor or a registered dietitian if you are concerned about vitamin deficiency

To find out more about how you can eat the way your body loves and give it all the micronutrients it needs, sign up for our newsletter.‍

Find out more:

• The Role of Vitamins and Minerals on the Immune System
• Zinc supplementation for the prevention of acute lower respiratory infection in children in developing countries: meta-analysis and meta-regression of randomized trials.
• The sun goes down on Vitamin D: why I changed my mind about this celebrated supplement – The Conversation
• Effects of vitamin D supplements on influenza A illness during the 2009 H1N1 pandemic: a randomized controlled trial.
• Vitamin C and Infections
• Do vitamins in pills differ from those in food? – Scientific American
• Fact or Fiction?: Vitamin Supplements Improve Your Health – Scientific American
• Coronavirus: how to keep your gut microbiome healthy to fight COVID-19 – The Conversation
• The Diet Myth - Tim Spector
• Spoon Fed - Tim Spector