Can you boost your immunity through food?
Recipe by Marnie Nitschke, Accredited Practicing Dietitian at Fork That Nutrition & Cockatoo Grove Ambassador.
The short answer is – yes! Eating enough food (and the right balance) is essential to provide our bodies with the nutrients our immune system needs. Here, we’ll take a look at some of the key nutrients that can affect our immunity, and their food sources. We’ll also look at gut health, and why it’s so important to a thriving immune system.
The immune system, in a nutshell
Our immune system is really complex! It involves cells, chemical messengers, tissues and organs. Its main job is to protect the body against infection – which it does by recognising invaders that don’t belong (bacteria, viruses and abnormal cells), and mounting an attack against them. Importantly, our immune system also has a memory, and can distinguish between harmful pathogens and helpful ‘symbiotic’ organisms.
Pretty amazing hey?
Why gut health is so important for good immune function
Our gut is basically a long, winding tube that runs right through our body. From the moment we’re born, our intestines are exposed to potential pathogens through eating, drinking, kissing, mouthing and licking. Just imagine how many things go into a baby’s mouth every day!
For this reason, it makes sense that our gut needs to be very good at fighting off potential nasties. In fact, the Gut Associated Lymphoid Tissue (GALT) in and around our intestine represents a huge 70% of our entire immune system. The GALT and our gut microbes work very closely together to keep us safe and healthy.
A strong, healthy gut environment will have a secure gut lining (that lets in nutrients but keeps out the things we don’t want). Importantly, it will also be home to a diverse population of billions of friendly gut microbes.
Top tips for nurturing your gut health and GALT
Eat lots of plant foods – fruits, vegetables, legumes, nuts, seeds and whole grains will provide the fibre and prebiotics to feed your gut microbes and keep everything harmonious. Aiming for 30 different plant foods each week is a great way to do this.
Reduce your intake of ultra-processed foods (like preserved meats, commercial biscuits, packet sauces) and artificial sweeteners, which can break down the mucous lining of our gut, and make it more susceptible to pathogens.
Include fermented foods like sauerkraut, kimchi, miso, tempeh, kefir and kombucha, which can help promote the diversity of our gut microbiome.
Eat more polyphenol-rich foods like berries, tomatoes, Extra Virgin Olive Oil, dark chocolate, tea, herbs and spices. Embrace chili, cloves, turmeric, ginger and cinnamon in cooking. Our gut bugs love polyphenols, and the metabolites they produce play a nurturing and protecting role in our gut health.
Prioritise a good sleep! Most adults need at least 7-8 hours each night, to support optimal digestive function and immunity. We also tend to eat differently when we’re under-slept. Studies have shown a greater incidence of impulsive eating and preference for salty, sugary and fast foods in people subjected to sleep deprivation.
Targeted probiotic strains can be a helpful adjunct to boost your immunity, and can be found in probiotic yoghurts, drinks, capsules and powders. Certain strains have been shown to influence our immune system and provide increased protection against colds, respiratory infections, gastroenteritis and travelers diarrhoea.
Here are a few key probiotic strains with evidence for improving immune function, and reducing the winter coughs and colds:
- Lactobacillus rhamnosus GG (LGG)
A widely studied probiotic strain, with evidence to suggest it can reduce the duration and severity of respiratory tract infections and gastrointestinal illness, particularly in children. Example product: Vaalia probiotic yoghurt, Farmers Union ‘Gut Good’ yoghurt.
- Lactobacillus acidophilus NCFM
Shown in clinical trials to reduce cold and flu-like symptoms, by supporting the gut-immune axis. Example product: Inner Health Plus double strength probiotic.
- Bifidobacterium lactis Bi-07 (or BB-12)
Often paired with L. acidophilus in research. Associated with improved immune cell activity and reduced frequency of upper respiratory tract infections. Example Product: Life-Space Broad Spectrum Probiotic Advanced.
What are the most important nutrients for a thriving immune system?
OK! LETS GO ...
Protein, B12, iron and zinc
These key nutrients are vital to the many different immune cells we produce, and deficiencies can impact the health of our immune system, and our ability to protect ourselves from common illnesses. Zinc is also important for gut epithelial cells and barrier function.
Good sources of these nutrients include red meat, chicken, fish, shellfish and eggs – servings don’t have to be big to really pack a punch.
Vegetarian sources are a little harder to absorb, so if you’re vegetarian you’ll have to work harder to get these nutrients: include lots of green leafy veggies, nuts, seeds and legumes. Because absorbable B12 is only found in animal foods, vegans will need to take a supplement, and have their B12 and iron levels tested regularly.
Vitamins A (Beta carotene) and C
Both these vitamins are important for optimal immune function, and deficiency is associated with poor healing, reduced skin integrity and immunity. Great food sources include sweet potatoes, spinach, carrots, citrus, berries, mango, broccoli and tomatoes. Green and orange veggies are the way to go.
Vitamin E
Vitamin E actually acts as an antioxidant – reducing inflammation and damage in our body. It has been shown to be important for specific immune cells (including the intense-sounding ‘natural killer cells’), as well as enzyme reactions and signalling molecules of our immune system. Sources of vitamin E include avocado, nuts, seeds (eg. flaxseed / linseed) and vegetable oils (particularly soybean, sunflower, corn, walnut, and wheat germ). Supplementary doses have been shown in some studies to enhance immune activity and resistance to infection.
Vitamin D
Often known as the sunshine vitamin – is key for immune function, with deficiency known to affect healing and inflammation levels in our body. Dietary sources include fatty fish, eggs, vitamin D-fortified foods like milk, juice or margarine and vitamin UV activated mushrooms.
Did you know that you can give common supermarket mushrooms a vitamin D boost at home? Just place them (gills up) outside or on the window sill for 30 minutes! We also produce vitamin D in our skin, when it’s exposed to sunlight, but many of us will have suboptimal or deficient levels of Vitamin D in winter.
This is especially true for the elderly, those with darker skin and those who don’t get outside much. Get your vitamin D levels tested, and take an oral supplement if recommended by your doctor.
What about ‘immune boosting’ supplements, teas and powders?
This is the part when I tell you that eating a really diverse and adequate diet (full of all the foods discussed here) is the best way to boost your immune system. While nutrient supplements are needed sometimes (when your diet is lacking and blood levels are deficient), there is little evidence for supplements boosting immunity in healthy individuals.
Water soluble vitamins like B and C vitamins can’t be stored by our body, so mega doses of these will just result in more being excreted in your urine. Fat soluble vitamins like A, D, E and K can build up in the body if taken inappropriately. It’s best to consult your doctor or an Accredited Practising Dietitian for individual advice on supplements and functional foods like pre- and probiotics.
Final thoughts
Our diet isn’t the only important factor in a healthy immune system and good immunity against colds and infections – but it is super important! Because it is rich in plant polyphenols, Extra Virgin Olive Oil can play a delicious role in helping you support your best nutrition and immunity. A healthy lifestyle with frequent exercise, good sleep and stress management will also help to optimise your immunity and energy levels.
