Immune Health During Winter

Cold and flu season is here again, along with the extra challenges this year of covid and rhinovirus as the world opens again, increasing the exposure of Australians to illnesses that we’ve managed to avoid for a couple of years. 

In addition to the usual precautions of vaccinations, hand washing and mask wearing as appropriate there are diet and lifestyle factors that you can add into your routine if you haven’t already that will help you sail through these challenges with as little disruption as possible.


Lack of sleep can decrease your immunity, making you more likely to become sick if exposed to an infection and affecting how long it takes you to recover after getting sick.  During sleep your body releases proteins called cytokines, which are needed if there is inflammation or infection or when you’re under stress.  Lack of sleep may decrease the production of cytokines.  Infection fighting antibodies and immune cells are suppressed when you are not getting enough sleep.

Prolonged stress can also have a negative impact on immunity.  Stress is the physiological or psychological response to challenging circumstances.  The immune system functions in response to stress.  Acute stress over a few minutes rallies the immune system and clotting factors in preparation for injury or infection.  Chronic stress, which can last from days to years, leads to a high amount of these pro-inflammatory substances that are ordinarily meant to protect you in the short-term floating around in the blood stream for days, or years.  This leads to an increased risk of chronic illnesses, such as atherosclerosis, or auto-immune disease, or reactivation of latent viruses.  (That’s why people tend to get cold sores while they’re stressed!)  Also, stress affects our brain chemistry, destabilising happy neurotransmitter serotonin, 90% of which is made in our gut (not our brains).  Around 70% of our immune surveillance occurs in our digestive systems, so a chemical destabilisation on that level in the gut will of course affect our immune systems.

The way to look after yourself and support your immune system, especially in winter and during the pandemic as we ride the peaks and troughs of COVID surges is to really prioritise rest.  Do the things that calm you.  Go to bed early.  Develop practices and routines that nurture your mental and physical health.  Your immune system will thank you.

I have written about how to get better sleep.  Here are my recommendations on Good Sleep Hygiene and I also wrote about tips for better sleep for people who are Wired and Tired

Dietary Suggestions

Starting your day with a meal of complex carbohydrates including oatmeal, whole grains nuts and fruits leaves you feeling fuller for longer, which will stabilise your blood sugar and your mood, enabling you to maintain focus for longer.  Complex carbohydrates include both soluble and insoluble fibre and starch.  Insoluble fibre promotes bowel health and regularity and support insulin sensitivity.  Soluble fibre dissolves in water and forms a gel that moves slowly through the gut, where it is used as a food source for good gut bacteria.  It also has been found to reduce blood cholesterol and improves blood glucose control. 

Oats in particular are highly nutritious, being rich in manganese, phosphorus, magnesium, copper, ion, zinc and Vitamins B1 and B5.  Coats contain beta glucans, a soluble fibre that reduces LDL and total cholesterol, reduces blood sugar and feeds the good bacteria in the gut.  In Traditional Chinese Medicine, oats build and regulate qi energy, making it excellent for nurturing people who are nervous, run down or recovering from illness.

Vitamin C and Zinc work together to support healthy immune systems.  Both are used to make healthy mucous membranes and collagen, improving the barrier functions in the body.  Vitamin C is a potent antioxidant that strengthens blood vessels, especially if eaten in the form of citrus fruit with some of the white pith still on. 

If you wanted to read more about how elevated blood sugar and vitamin C affects immunity I have written a great article here.

Food sources of vitamin C are citrus fruits, kiwi, berries, broccoli, pumpkin, sweet potato and spinach.  Frozen is fine if that’s what you can get, as it’s often cheaper and snap frozen while at optimum nutrient levels. 
Food sources of zinc – meat, shellfish, dairy, legumes and nuts

Vitamin D deficiency is still quite high among Australians especially in the middle of winter.  It helps the body to absorb and retain calcium and phosphorus, making it very important for bone health.  Vitamin D also reduces inflammation and helps control infections by modulating the innate and adaptive immune response.   Vitamin D levels in our bodies fluctuate with the seasons, with the levels typically being highest during the Summer and lowest during the Winter, which would relate to sun exposure and the amount of skin we have uncovered during those times.  It comes as no surprise then that we are more vulnerable to infections during the cooler months as the Vitamin D levels in our bodies naturally decline.

Sources of Vitamin D – sun exposure as per Australian Cancer Council guidelines and foods such as eggs, mushrooms, fatty fish (salmon, mackerel, sardines) and fortified milk.

In winter we are more like to crave more comfort foods that are high in sugar and saturated fat, such as pastries and the good old mac and cheese.  This is because energy dense foods warm you up quickly, but it’s important that we choose energy dense foods that are nutrient dense as well.  Healthy fats such as omega 3’s, omega 6’s and poly unsaturated fats reduce over-eating by helping us feel full for longer and they are very useful within the body for good heart health, healthy cells and maintaining hormone function.  Omega 3’s, omega 6’s and poly and monounsaturated fatty acids are important to immunity as a source of energy, as structural components of cell membranes, as signalling molecules and as precursors for the synthesis of white blood cells and other chemical mediators utilised by the immune system.

Sources of Omega 3 fatty acids are oily fish (salmon, mackerel, sardines)

Sources of Omega 6 fatty acids – nuts (especially walnuts), seeds (chia seeds) and olives

Monounsaturated fats – avocado, almonds, hazelnuts and pecans, pumpkin seeds, sesame seeds

Polyunsaturated fats – flaxseed oil, sunflower oil, walnuts, flax seeds, fish

Fermented foods help populate the gut with a wide range of healthy and diverse microbes, which maintain good digestive health.  This is important in supporting immunity as the digestive system is an important barrier for protecting us from the rest of the world, protecting us from disease and infection, with up to 70% of our immune function, both innate and adaptive, taking place in the digestive system. 

Sources of probiotics – yoghurt, kim chi, sauerkraut, miso, kefir,

There are also foods that specifically support immunity because of the nutrients, antioxidants and phytochemicals they contain which reduce inflammation in our bodies.  These are onions, garlic, ginger, turmeric, chilli (check out my Vege Curry for a recipe that includes all of these ingredient), fresh herbs, spices, blueberries, apples, dark green leafy vegetables, beetroot (Click here for my beetroot Borscht recipe) and mushrooms of all kinds.  When choosing fruit and veg to eat to support immunity, choose those which are brightly coloured and eat a wide variety of different colours to make sure all the bases are covered.

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