Your immune system is your body’s defence against illness and infection. It’s a network of cells, tissues and organs that work together to protect against harmful pathogens like bacteria and viruses. Having a strong immune system helps stop you getting sick. So what can you do to maintain it? Here we look at lifestyle factors like diet, exercise and stress management that support immune health.
How Stress Impacts Immunity
Feeling constantly stressed activates your body’s physiological stress response. This prepares you to deal with perceived threats by increasing alertness and tensing muscles. While this can be helpful for short-term ‘fight or flight’ situations, ongoing stress keeps your body in a constant state of high alert.
Chronic stress causes elevated levels of the hormone cortisol. This can suppress and disrupt the proper functioning of the immune system. As a result, prolonged periods of stress make you more susceptible to illness and infection.
Studies show that chronic stress increases production of the hormone corticotropin-releasing factor (CRF). Higher CRF levels inhibit important immune cells called leukocytes from migrating to sites of infection and inflammation in the body. This reduces the ability of your immune system to do its job.
Stress also causes a decrease in lymphocytes, white blood cells that help the body fight disease. This makes it harder for your body to mount an appropriate immune defence when faced with viruses or bacterial infections.
Managing stress is therefore critical for keeping cortisol, CRF and inflammation under control so your immune cells can function optimally.
To minimise the immune-compromising effects of stress, focus on relaxation and stress management techniques like:
- Regular exercise – releases endorphins which boost mood
- Good sleep hygiene and habits
- Limiting intake of alcohol and caffeine
- Talking through worries or journaling
- Spending time with supportive friends
- Practicing mindfulness, meditation or breathing exercises
- Doing enjoyable hobbies and activities
Making lifestyle changes to reduce stress can help strengthen your immunity.
Nutrition For Immune Health
Eating a nutritious, balanced diet gives your immune system the vitamins, minerals and nutrients it needs to work effectively. While no single food can meet all your immune needs, getting a variety of these vitamins and minerals from different sources is key:
Vitamin C – Found in citrus fruits, peppers, broccoli, berries and kiwi fruit. Vitamin C is a potent antioxidant that supports the production and function of immune cells.
Vitamin D – Made in the body from sunlight and found in oily fish, eggs and fortified foods. Vitamin D helps regulate immune responses. Most people require supplementation, especially in winter.
Zinc – Present in meat, shellfish, eggs, nuts, seeds and wholegrains. Zinc assists with development and communication between immune cells.
Vitamin A – Found in liver, dairy products, leafy greens and orange veg like carrots. Vitamin A keeps mucous membranes in the eyes, lungs and gut healthy to prevent entry of germs.
Selenium – Found in selenium-rich soils and absorbed by grains, meat, eggs, nuts and shellfish. Selenium helps immune cells reproduce and function optimally.
Probiotics – Found in fermented foods like yogurt, kimchi and kefir. The healthy gut bacteria boost immunity by competing with harmful pathogens.
Other key immunity boosting nutrients include:
Iron – Iron helps carry oxygen around the body in red blood cells. Low levels can reduce cell-mediated immune function. Get iron from meat, seafood, legumes, fortified cereals and dark leafy greens.
Protein – Important for production of antibodies and immune cells. Eat lean meats, eggs, dairy, beans, lentils, nuts and seeds.
Prebiotics – Prebiotics feed probiotics and are found in bananas, onions, garlic, leeks and artichokes.
Polyphenols – Abundant in fruits, vegetables, coffee, tea, red wine and dark chocolate, polyphenols are antioxidants that help immune cells neutralise pathogens.
Making sure your diet includes plenty of fruits, vegetables, lean proteins, nuts, seeds and whole grains will help provide varied nutrients to support a robust immune response.
Exercise To Boost Immunity
Regular moderate exercise has been shown to benefit immune health in several ways:
- Improved circulation allows immune cells to travel through the body more efficiently to sites of infection.
- Exercising causes a short-term rise in stress hormones that gives immune cells a readiness drill, preparing them to be triggered when needed.
- It lowers levels of inflammation in the body. Chronic inflammation can impair immune responses.
- It enhances the coordinated regulation of the immune system.
- Active people tend to have more effective pathogen-fighting antibodies and cells compared to sedentary people.
The best evidence indicates that 30-60 minutes of moderate exercise 5 days per week provides the most immune benefit. This could include activities like brisk walking, swimming, cycling, dancing, tennis and yoga.
Aim to get your heart rate elevated to around 50-70% of your maximum, while still being able to maintain a conversation. For most people, this means exercising at an intensity of 12-14 on a 20 point Borg scale of perceived exertion.
Exercising outdoors is great for also getting some immune-boosting vitamin D from sunlight. But if it’s cold, icy or you feel unwell, adjust your workout to avoid injury and further stress on the body. Activities like yoga, pilates, indoor cycling or cardio videos can be done in a warm environment instead.
While prolonged, intense cardio like marathon training can sometimes depress immunity, evidence indicates that moderate regular exercise prevents this. Light exercise like taking the stairs, gardening and active chores also contribute to an overall active lifestyle that supports immune resilience.
If new to exercise, build up the duration, frequency and intensity gradually. Even 10-15 minutes a day is beneficial. Consistency over time has the greatest impact on immunity, so find types of exercise you enjoy and make movement a lifelong habit.
Aim for 150 minutes of moderate exercise like brisk walking or cycling per week. This could be 30 minutes a day, 5 days a week. Even light exercise is beneficial. Start slow if new to exercising and build up gradually.
Immunity-Boosting Foods
Specific foods containing high levels of nutrients that support immune function include:
Citrus Fruits – Oranges, lemons, limes and grapefruit are packed with vitamin C. Enjoy the fruits themselves or juice them to bump up C intake.
Red Peppers – These vibrant veg contain even more vitamin C than citrus fruits. Eat raw with dips or add roasted peppers to salads, pastas and pizzas.
Broccoli – A great source of vitamins A, C and E, as well as fibre. Enjoy it lightly steamed, roasted or raw in salads.
Garlic – Garlic’s antimicrobial properties help fight viruses and bacteria. Use it crushed or minced in dishes for the most benefit.
Ginger – Gingerol, the bioactive substance in ginger, is a powerful anti-inflammatory and antioxidant. Enjoy in stir fries, broths, baked goods and tea.
Yogurt – Probiotic yogurt contains beneficial bacteria that support gut and immune health. Look for unsweetened varieties.
Almonds – Rich in antioxidant vitamin E, manganese and magnesium, nutrients that assist immune cell function. Enjoy almonds raw or toasted as a snack.
Turmeric – The curcumin in turmeric has antioxidant and anti-inflammatory effects. Use the spice in curries, soups, smoothies and more.
Green Tea – The polyphenols in green tea protect against oxidant damage and enhance immunity. Sip regularly as a hydrating drink.
Other foods high in immunity enhancing compounds include:
Poultry – Chicken and turkey contain vitamin B6 that assists antibody production and zinc for immune cell growth. Remove skin and cook lean portions.
Sunflower seeds – An excellent source of selenium and vitamin E which act as antioxidants and support immunity.
Oily fish – Salmon, mackerel, sardines and tuna are rich in omega-3s and vitamin D to regulate immune responses.
Sweet potatoes – Packed with beta carotene that converts to vitamin A, vital for skin and mucous membrane barriers against bacteria and viruses.
Mushrooms – Mushrooms contain antioxidants as well as selenium, zinc, B vitamins and vitamin D. Shiitake and maitake offer the most immune benefits.
Papaya – Papaya is rich in vitamin C and the antioxidant beta-cryptoxanthin that may enhance immune function.
Kiwi – Kiwis are an excellent source of vitamin C, antioxidants and fibre that benefit the immune system.
Spinach – Spinach provides vitamin C, beta carotene, zinc and iron for immunity. Lightly cook to increase its antioxidant availability.
Eating a rainbow of brightly coloured fruits and vegetables ensures you get a wide range of protective antioxidants and phytochemicals to strengthen your body’s defences.
Supporting Your Immune Health
Here are some key tips for keeping your immune system strong and resilient:
- Reduce stress through relaxing activities like yoga, deep breathing and meditation.
- Exercise regularly with moderate intensity cardio and strength training.
- Get enough sleep – aim for 7-8 hours per night minimum.
- Eat a balanced diet full of varied fruits, vegetables, lean proteins and whole grains.
- Stay hydrated by drinking water throughout the day.
- Take supplements like vitamin C, vitamin D, zinc and elderberry syrup which assist immunity.
- Stop smoking – smoking impairs lung and immune function.
- Cut back on alcohol – excess alcohol suppresses immune responses.
- Handle food safely – cook meat thoroughly and wash produce to avoid pathogens.
Some other tips for optimising immune defences include:
- Wash hands regularly and avoid touching your face to prevent spread of germs.
- Open windows regularly to circulate fresh air and limit buildup of bugs.
- Clean surfaces like sinks, counters and toilet seats frequently with disinfectant.
- Get an annual flu shot to protect against influenza viruses.
- Stay up to date with other vaccinations like tetanus, pneumonia and shingles.
- Avoid sharing cups, cutlery and towels with someone who is sick.
- Stay home from work if you feel unwell to prevent infecting others.
- See your doctor if you have recurrent infections as you may need testing.
Supporting your immune health takes consistency and making healthy lifestyle choices over the long term. But the effort is well worth it for staying happy and healthy all year round.
Photo by @rw.studios on Unsplash
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