The Truth About 'Boosting' Your Immune System Against Covid-19

Smoothie and supplement companies might get your hopes up, but "medically, it doesn’t really make sense".

There’s no shortage of articles advising you how to “boost” your immune system against Covid-19 – and no shortage of companies claiming their snack bar/smoothie/supplement/fermented tea is the solution.

But if staving off coronavirus was as simple as eating a few blueberries or downing some kombucha, wouldn’t world leaders be telling us to do it?

“There’s no way you can scientifically ‘boost’ your immune system,” Dr Jenna Macciochi, an immunologist based at the University of Sussex, tells HuffPost UK. “Medically, it doesn’t really make sense – the immune system isn’t a switch that you turn on and turn up high.”

Why do scientists hate the term ‘boosting’ your immune system?

Broadly speaking, the immune system works in two ways. Firstly, by sparking a first-line defence to help us cope with infections such as Covid-19, then secondly – at around five to seven days – the body will start making antibodies and have a more specific immune response tailored to the virus.

If someone’s immune system is operating at a higher level than normal, this is actually a bad thing. Having an overactive immune response can cause an autoimmune reaction, when the body mistakingly starts to attack its own healthy tissues and organs.

“If it goes into overdrive, we’ll actually damage our own bodies and that’s what we see with severe Covid,” explains Dr Macciochi. “With a lot of the people who are hospitalised with Covid, it’s actually because their immune system has gone a bit over the top.”

Okay, but isn’t having a strong immune system a good thing?

It’s a common misconception to talk about the immune system as a binary of “weak” or “strong”, says Dr Macciochi. Instead, the system represents a “hugely complex dance that’s happening between many different components”.

“It’s like an orchestra,” she explains, “it all has to play together for the song to sound correct. If one of the instruments is screeching in the background, it knocks everything else out.”

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We inherit some of the key components of our immune systems through our genes, making them unique. “Some people suffer colds really badly, for example, but they never get a stomach upset,” explains Dr Macciochi. “There’s inherent differences in us.”

Everyone has their own individual base level of immunity, let’s call this 100%. While you can’t “boost” your immune system to work at 110% – or make yourself magically immune to Covid-19 – you can support it to function at its fullest.

“Potentially, you’re sort of giving yourself the best chance of not having Covid-19 too severely and recovering,” explains Dr Macciochi.

How can you give your immune system the best shot?

Eating a balanced diet to ensure you’re not deficient in any key nutrients is a key way to help your immune system function at its best.

“That’s not just the classic vitamin C and zinc, but all the essential nutrients and getting enough protein, because that’s the building block of all the cells and antibodies of our immune system,” says Dr Macciochi.

Taking care of the gut is a good idea for health in general, as is aiming for 30 different plant foods per week, she says. You should also focus on “diversity of dietary fibre”, which means eating a variety of fruit, veg, legume, nuts, seeds and whole grains.

Unfortunately, psychological stress has been found to hinder the immune system – something unavoidable in the global pandemic. But Dr Macciochi says getting enough rest and good quality sleep can help.

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What about those vitamin D headlines?

In short, the jury is still out. There’s been much debate about the use of vitamin D supplements to fight Covid-19 and even Matt Hancock seems a little confused about the research that has and hasn’t happened.

A paper published in the Lancet journal casts some doubt on the evidence to date, saying “laboratory data relating to effects of vitamin D on host responses to SARS-CoV-2 specifically are scarce”. The authors say we need further studies before making firm conclusions, but add “there is nothing to lose” from considering vitamin D supplements.

Dr Macciochi says vitamin D is the one supplement people may want to consider taking, as it’s hard to get from food alone. But she urges caution in seeing any supplement – including vitamin D – as a solution and emphasises that we need to follow guidelines on social distancing, masks and good hygiene practices as the priority.

“Be aware of marketing claims as supplements are able to state their product is good for immunity if it contains a key nutrients needed by our immune system,” she says. “No supplement will be a magic quick fix because health is complex – and the immune system is mind-bogglingly complex.”