Gut Health for Cold and Flu Season

When people think cold and flu prevention, they don’t often think about the importance of gut health for immune resilience.  Read ahead for some gut health tips for preventing colds, flu and other common infections.

What’s a leaky gut and what’s the connection between how a leaky gut can weaken your immune system?

The gut and the immune system are intricately intertwined.  Consider the fact that the gut is a major gateway of foreign substances into the body, and it becomes understandable that a whopping 80% of our immune system is actually located in the gut lining – in what is called gut associated lymphoid tissue, or GALT for short.   Our gut lining is protected by an abundance of beneficial bacteria and a series of mechanisms, such as tight-junctions between cells, to help moderate what substances are allowed entry into the blood stream.

If the gut lining becomes damaged, or if it is exposed to irritating foods, toxins and / or pathogens, it can become “leaky”.  The medical term is intestinal hyperpermeability, more commonly known as leaky gut.  When the gut is leaky, substances that normally wouldn’t be able to enter the blood stream are able to enter.  When this happens it triggers the immune system into responding to the influx of foreign agents and an inflammatory cascade begins.  If the exposure is constant, or the permeability is not restored to its appropriate state, this inflammatory process can become chronic.  It usually coincides with a situation called dysbiosis (an imbalance of good and opportunistic microbes in the gut).  Overgrowths of opportunistic bacteria produce a substances called lipopolysaccahide (LPS) which can then enter the blood stream through the leaky gut and result in chronic inflammation and a disrupted immune system, leaving some people more susceptible to recurrent or chronic infections, others to atopic conditions like asthma and eczema, and others to autoimmune conditions such as hashimoto’s thyroiditis.

Leaky gut affects immune function by initiating an inflammatory response

How does gut health affect immunity as it relates to the common cold and illnesses like the flu? 

With so much research on the microbiota (gut bugs) coming out, most people now know probiotics have a beneficial effect on the digestive system, however their work does not just stop there.  Probiotics have a regulatory role on the immune system (most of which is found in the lining of the gut).

Several strains of probiotics in the gut increase the production of immunoglobulins and specialised immune cells called Natural Killer cells (NK cells) and T Lymphocytes (T cells) which protect us against infection, including against flu and common cold.

For example, a 2015 study in the UK of highly stressed undergraduate students showed that daily consumption of the probiotic Bifidobacterium bifidum reduced the number of sick days among 581 students, compared to placebo.

Foods to include for keeping immunity strong through winter

The three super foods for great immune function are bone broth, fermented foods and cod liver oil (and or organic liver).  The combination of these foods provide a power-packed wealth of minerals, enzymes, probiotics and vitamins, especially vitamins A, D, and C which all play important roles in immune function and have antiviral activity.

Fermented foods include things like fermented veggies (think sauerkraut or kim chi), water kefir or coconut water kefir (probiotic fizzy drinks) and coconut yoghurt to name just a few.  With fermented veggies, it’s always best to start with a small amount – even just a teaspoon of the juice of the veggies, and slowly increase.  This is so that kids (and adults) get used to the flavour (if they’re not used to having sour / tart foods) and so that you’re introducing beneficial bacteria slowly.  Introducing too much too quickly can result in bloating, burping or excessive flatulence – not particularly socially acceptable!

To help probiotics colonise and stay in the gut, be sure to consume plenty of prebiotics too.  Prebiotics are the foods that probiotics (friendly bacteria) like to eat.  Prebiotics are found in vegetables – so have plentiful veggies in the diet of you and your kids.  Eat the rainbow.

With Cod Liver Oil, choose a high quality brand – you usually get what you pay for – and have about a teaspoon per day (kids and adults alike).

For bone broth, anywhere from half a cup to 4 cups a day.  Enjoy as a drink on it’s own (season with salt and pepper and herbs if desired, or add to cooking).

Dietary Immune Destroyer

The number one item to avoid is without doubt, Sugar.  Sugar inhibits phagocytosis – the action of engulfing viruses and bacteria by neutrophils (a type of white blood cell), effectively suppressing immune function.

Lifestyle choices effect immune function

The biggies here that are well studied include sleep, stress, exercise and social isolation.  Not enough sleep or exercise and too much stress or social isolation all inhibit immune function, so be sure to get adequate and good quality sleep, practice stress management techniques, move your body (preferably in a nature) in a way appropriate to your needs and capability and connect with friends and family who you feel good around.




Langkamp-Henken B, Rowe CC, Ford AL, et al. Bifidobacterium bifidum R0071 results in a greater proportion of healthy days and a lower percentage of academically stressed students reporting a day of cold/flu: a randomised, double-blind, placebo-controlled study. Br J Nutr. 2015 Feb 14;113(3):426-34. doi: 10.1017/S0007114514003997.