Eating well and being active are two key steps you can take to improve your immune fitness and resilience to infection.
As I explained last week in Good Health, looking after your immunity doesn’t mean you won’t ever get ill, but it does improve your body’s capacity to respond and adapt to challenges effectively and get back to a healthy state.
As well as being physically active and nourishing gut bacteria, which is key to immune fitness, there are specific steps you can take to ward off infection — it is vital, for instance, to avoid deficiencies in essential vitamins and minerals.
When it comes to respiratory infections such as colds and flu, vitamin D takes centre stage.
When you’re ill your immune system requires resourcing and time. Resourcing means focusing on a healthy diet, plenty of sleep and rest and not too much stress, which collectively help equip your immune system to battle pathogens, alleviate symptoms and restore you to health
Approximately one person in five has vitamin D levels low enough to reduce the effectiveness of the immune defences. Keeping up with your vitamin D supplementation all year round is important.
It’s also a good idea to prioritise protein — which helps us build antibodies and repair our tissues — and omega-3 fats, which can inactivate certain viruses by making the conditions in our cells less favourable for them to replicate.
But if you do come down with an infection, whether it’s a cough, cold or a mild case of Covid-19, the framework here can help get you on the road to recovery.
If you do catch a bug…
When you’re ill your immune system requires resourcing and time. Resourcing means focusing on a healthy diet, plenty of sleep and rest and not too much stress, which collectively help equip your immune system to battle pathogens, alleviate symptoms and restore you to health.
But time is crucial, too. When we become infected, the immune system searches in the 10 billion-strong pool of antibodies and 100,000 T cells — specialist cells that seek out and destroy pathogens — to select those capable of binding to that specific virus.
When a match is found, the B cell responsible for producing that antibody starts a factory to produce more — also refining that antibody so it binds to the germ more effectively. Specific T cells that bind to that germ are selected and multiplied; they also develop specialised functions to deal with the threat.
Building armies of highly specific T cells and antibody-producing B cells can take days or weeks; it even needs a few days to reactivate immunity you already have.
This is why symptoms — a side-effect of the immune system doing its job — can start days or weeks after you have been infected.
- Accept a fever: It is a symptom of the immune system doing its job and it is generally OK to let a fever run its course. Recent evidence suggests we should hold back on taking drugs to reduce the fever (such as paracetamol) unless it becomes too distressing.
- Prioritise rest and sleep: Sleep is more important than ever when fighting an infection, but infection is a sleep disruptor. In fact, changes to your sleep pattern might be an early indicator of infection. Fighting infection often requires more sleep, so you’re likely to feel sleepy as infection-fighting immune cells act on neurons in the brain, signalling to increase sleep and dampening wake-promoting chemical messages.
Accept a fever: It is a symptom of the immune system doing its job and it is generally OK to let a fever run its course.
- As well as allowing the immune system to produce more infection-fighting substances, sleep aids the formation of the brain messengers needed to enhance your T cell response. Rest really is the best medicine.
- Drink plenty of fluids: The reason we’re always told this is because hydration keeps your mucus membranes soft and moist, helping this barrier resist infection. It’s also important for the flow of blood and lymph around the body, keeping tissues well oxygenated and allowing immune cells to perform their surveillance.
Eat to get better
Appetite is naturally suppressed when we’re sick as a protective mechanism to conserve energy used by the digestive system.
There are several nutrients that can support the extra demands your body makes when you’re ill, and which help counterbalance inflammation (your immune system’s response to germs but which, if it becomes chronic, is also the key risk factor for serious diseases), provide symptom relief and possibly help shorten the duration of the illness.
Protein: When you’re unwell, aim for 1.5g/kg/day (so if you weigh 70kg that’s around 100g of protein a day) and focus on sources high in the amino acids glutamine and arginine, which are used at a higher rate by the immune system during illness, helping to inhibit inflammatory responses. White meat is a rich source (one reason why chicken soup is considered an antidote to colds and flu) but these amino acids can also be found in nuts, beans and legumes.
Vitamin c: When you’re fighting an infection, your immune system uses more vitamin C. Eating more foods rich in vitamin C such as citrus fruits and berries or supplementing with up to 1g a day can reduce the duration and severity of symptoms (although high doses can upset the digestive tract).
Maximise the benefits by eating whole fruit because beneficial compounds such as quercetin are often found in the pulp and the white core of fruits high in vitamin C and, acting with the vitamin, support the immune response.
Zinc: A key nutrient in tackling infection, zinc is found in meat, poultry, shellfish, nuts and seeds. Taking supplemental small doses over the day (total daily dose of 10-40mg) can substantially reduce the duration of common colds. Take the flavonoid quercetin at the same time because it helps zinc get inside your cells and has its own antiviral properties.
Selenium: Lack of selenium allows pathogens to mutate and infect for longer, so a supplement can be useful for the elderly and those at risk. Brazil nuts, seafood and offal are the richest sources.
Berries: The deep red and purple polyphenols (beneficial plant compounds) found in berries are packed with antioxidants and anti-inflammatory compounds, but also show antiviral properties.
The road to recovery
When an acute infection starts to resolve, the focus needs to shift to calming any inflammation your immune response might have triggered. Again, it’s important to prioritise rest and restorative sleep.
Any inflammatory response will result in a degree of oxidative stress, which could deplete nutrients but you can counter this:
Omega-3s (in supplements or oily fish) are my top choice for promoting a return to normal because of their ability to calm the inflammatory process before it gets out of hand and starts to damage cells. While the usual dose is 250-500mg (combined EPA and DHA) each day, when recovering from infection, 1-3g can have a positive impact if used in the short term (don’t have more than 3g a day).
Bromelain is an enzyme from the fruit or stem of the pineapple plant. Studies show clinical benefit in injuries, infections and respiratory-tract diseases.
Note: Check with your doctor before taking supplements. Adapted from Your Blueprint For Strong Immunity by Dr Jenna Macciochi, published by Hodder on February 24 at £14.99. © Dr Jenna Macciochi 2022. To order a copy for £11.99 (offer valid to March 1; UK P&P free on orders over £20), visit mailshop.co.uk/books or call 020 3176 2937.
And why you should try these natural remedies
When you’re dealing with minor infections there are some natural antimicrobials which have been shown to effectively tackle pathogens:
- Oregano oil contains carvacrol and thymol, two powerful antibacterial compounds. Look for therapeutic-grade oil from a reputable herbalist and take one to two drops daily for 14 days.
- Honey has been shown to be a better alternative to over-the-counter medicines for tackling sore throats and coughs in children. Take 2.5ml daily when ill; mix with lemon and ginger for a soothing elixir. Manuka honey is a rich source of antimicrobials, with growing scientific evidence for healing wounds.
- Garlic contains compounds such as allicin, which have antimicrobial effects for treating and preventing upper respiratory viruses. One study showed a raw, crushed clove activates genes related to immune function (we need three times as much cooked garlic as some phytonutrients reduce with cooking). Chop or crush then leave it for a few minutes to let the reaction generating allicin to occur.
- Turmeric — active curcuminoids in turmeric have antiviral and antibacterial properties. Your body absorbs up to 2,000 per cent more when turmeric is paired with a dash of black pepper. Supplements can be taken in 500mg doses twice daily to reduce inflammation.
- Acetylcysteine is an amino acid derivative which interferes with viral replication and helps to thin mucous secretions, so the body can easily clear them; 600mg twice daily is effective in reducing respiratory viral symptoms.
- Ginger, cardamom, eucalyptus and clove— added to cooking or drinks — interfere with the process by which germs talk to each other and so help alleviate pain and inflammation.
- Mushrooms and yeasts offer a plethora of antimicrobial properties. Try eating more mushrooms in periods of extra stress, infection risk or at the first sign of a cold or other minor infection.
- Regular supplementation with lactoferrin (a protein in milk), from 600mg to 2g a day, has been shown to prevent colds and cold-related symptoms.