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As cases of coronaviruses grow around the world, we’re in no doubt that we need to wash our hands more. But what else can we do to give our immune systems a fighting chance of beating the virus if we are struck down, or preventing it altogether?

“This is a serious infection and no amount of lifestyle intervention will make you invincible,” says Dr Jenna Macciochi, an immunologist at the University of Sussex, whose timely new book, Immunity: The Science of Staying Well, is out on April 16.

“But there are plenty of small things you can do that may strengthen your immune system.”

1. Follow the advice... whatever your age

This is not the time to ignore public health messages, says Dr Ross Walton, a viral immunologist currently developing vaccines for flu. While the elderly are indeed more at risk, your immune system actually started to decline years ago. “Your thymus gland is where the body’s T cells [white blood cells that fight infection] are produced, and this starts to atrophy in your twenties,” says Dr Walton. “But that’s only one reason everyone should be taking these measures; the other is that healthy, relatively young people have a responsibility to stay well so they can avoid spreading an infection that could kill someone more vulnerable.”

2. Wash your hands with plenty of water

There’s handwashing and there’s handwashing during a global pandemic. When you wash your hands, it’s more about the water than the soap. “Warm water is better, but getting a lot of water over your hands while you’re rubbing them together is much more important than the amount of soap used.” Indeed, unless it’s antivirucidal, an antibacterial soap won’t kill the virus, anyway. As for gels, look for 60 per cent alcohol content, as this will have antibacterial and antivirucidal activity (but they won’t work at all if your hands are heavily soiled or greasy).

3. Eat a colourful Mediterranean diet

Eating a low-carbohydrate Mediterranean diet, rich in different coloured fruits and vegetables, will give you the best chance of getting the wide variety of antioxidant and anti-inflammatory phytonutrients your body needs to fight infection, says Dr Claire Bailey, a GP with a special interest in immunity and author of Clever Gut and Blood Sugar Diet. The more colours you include, the more nutrients you get. “Eat the fruits and vegetables ideally with the skin on, as this contains essential fibre that feeds the healthy bugs in your digestive tract, crucial to fighting infection.”

4. If you get symptoms, dose up on vitamin C

The kiwi fruit is also a good source of vitamin C

China might be running out of oranges, but there’s little evidence showing vitamin C prevents infection. “What the evidence does show is that once a cold has hit, vitamin C can shorten the duration of symptoms,” says Dr Macciochi. “Our immune cells have a high need for vitamin C when they are working hard to fight infection, so if you find yourself with symptoms, this is the time to start dosing up on vitamin C.” Oranges aren’t the only source, mind, it’s also kiwi fruits, red peppers, spinach, grapefruit, cauliflower and Brussels sprouts, as well as organ meats.

5. Don’t lose sleep over it

“Adequate sleep is the bedrock of your whole immune system,” says Dr Macciochi. “If you’re not sleeping, no other lifestyle measure will make such difference because while we sleep, the hormone melatonin stimulates new immune cells.”

6. Move around throughout your day – and build some muscle

Movement throughout the day is essential for your lymphatic system, which relies on movement and muscle for stimulation

Yet another reason to take that lunchtime walk. “Regular and often is the key for exercise and immunity,” says Dr Macciochi. “Movement throughout the day is essential for your lymphatic system, which relies on movement and muscle for stimulation. It’s essential to helping your immune cells perform their surveillance function of moving around the body fighting germs that might be trying to get inside your tissues.” And while it’s not exactly quick, strength training is essential to immunity as you age. “Muscle produces chemicals that work on our thymus gland (where immune cells are made) and can help its functioning as we get older.”

7. That two litres of water rule – heed it

“Hydration is critically important but vastly overlooked,” says Dr Walton. “So many metabolic functions rely on it.” Indeed, if you get dehydrated, it can change the mucus layer in your respiratory tract and your digestive tract that has antibodies that trap germs and stop them getting into your cells, Dr Macciochi points out. Oh, and tea and coffee are diuretics, so they don’t count.

8. Get enough vitamin D...

Pooled data from 16 clinical trials involving 7,400 people show that taking vitamin D supplements reduces the risk of experiencing at least one respiratory infection including influenza and pneumonia by a third with positive benefits seen within three weeks. In those with low vitamin D status, the protection was even greater, reducing the risk of respiratory infection by almost a half compared with placebo. Another analysis published in 2017 in the British Medical Journal looked at 25 studies and involved around 11,000 people from 14 countries. It found that vitamin D supplements reduced the risk of acute respiratory infections by 11 per cent compared with placebo. A cheek spray is great for fast absorption of vitamin D into your bloodstream.

9. ...and zinc

“We can’t make zinc in our bodies, we have to get it from our diets,” says Dr Macciochi. “Yet it plays a role in hundreds of reactions in our bodies and is extremely important to fighting infection. There’s some evidence that taking extra zinc in the winter months is helpful at preventing infection but zinc is not something to take all the time as it can cause toxicity.”

Food sources include red meat, shellfish, legumes, seeds and dark chocolate. 

10. Eat sourdough bread - and other gut-friendly fibre

Sourdough is one of the healthiest things you can eat for your microbiome, which is crucial to immunity

“Your gut bacteria – or microbiome – is crucial to immunity,” says Dr Macciochi. “This breaks down your food in the digestive tract and produces metabolites known as ‘post-biotics’ that are helpful for our immune systems.” But keeping your gut happy doesn’t only involve eating fashionable fermented foods such as kimchi, sauerkraut, kombucha and kefir. “These are important as they are the sources of healthy bugs,” says Dr Bailey. “However, what is even more important is getting the fibre foods that feed those healthy bugs and encourage them to grow.”

Sourdough is one of the healthiest things you can eat for your microbiome and a great source of fermented fibre, which is the best of both worlds, she explains. “Look for the slow-fermented variety from artisan bakers ideally made with a more ancient grain such as spelt, or einkorn.” Other gut-friendly fibres include fruit and vegetables, whole grains and legumes.

11. Add crushed garlic to your food

Garlic contains a compound that's known for its antibacterial, anti-inflammatory and antimicrobial effects

Those delicious bulbs contain a compound called allicin, well studied for its antibacterial, anti-inflammatory and antimicrobial effects, explains Dr Macciochi. “But this is only released when the garlic has been crushed and left to sit for a while, before use in cooking.” Meanwhile, some studies have tried to take this active ingredient out of garlic and make it into a supplement, but they haven’t been effective.

The Daily Telegraph