Gut Health in Cold and Flu Season

Updated: Aug 6, 2018

credit to @thefermentedkitchen

Like it or not, cold and flu season is here. So what are you going to do to fight off the bugs that give us that awful, lingering sore throat and “feeling flat” mood for weeks on end? We all know the usual messages - wash your hands, cough into your elbow, take vitamins and for god’s sake, don’t touch the hand rail! But what about our natural immunity? How can we use our body’s natural immune system to our greatest advantage during this cold and flu season?

Immune defence. You see it on various vitamin packets and Instagram accounts. Smoothie shops offer “immune boost shots” or various concoctions of certain juices that make an “immunity elixir” and even your grandma talks about ginger, lemon honey tea to fight off your sore throat. But what is this mystical, mythical “thing” that is supposed to help us fight “the bug”? It seems that everyone has an opinion on it. So what’s the deal? What is the evidence? What will REALY help your immune system stay strong?

Our body’s immune system is the complex network of organs, cells and proteins that is our body’s defence against infection. Our immune system keeps a detailed record of every germ (microbe) ever to be defeated on its turf so it can recognise and destroy it quickly the next time in enters the body. It is kind of like an OCD football coach, keeping track of new and old players on the opposing team and shouting orders to players to “watch out for Jimmy’s quick left side step”.

The most commonly known parts of the immune system are [1]:

- White blood cells

- Antibodies

- Complement system

- Lymphatic system

- Spleen

- Bone marrow

- Thymus

Other important body parts that form a part of the resistance are:

- Skin- water proof barrier to the outside

- Lungs- mucous in the lungs traps foreign particles that eventually get coughed out.

- Digestive tract- mucous lining in the gut contains antibodies and the acid in the stomach can kill many microbes.

Your gut (digestive tract) is not just good for extracting all the useful stuff (i.e. vitamins, minerals, energy, protein, fat) out of our food. It also integrates with many other systems in our body such as our circulatory system, nervous system and lymphatic system. Gut Associated Lymphoid Tissue (GALT) thinly lines our gut walls [2]. Its like your mother with eyes on the back of her head—it closely monitors everything that passes through the gut that could potentially be absorbed into your bloodstream and cause more havoc.

GALT is richly populated with Peyer’s Patches, which are very specialised small masses of lymphatic tissue found in our guts [2]. These are crucial for identifying the pathogenic (bad) bacteria, ensnaring them and disarming them. Picture GALT as the castle mote and fort walls and Peyer’s Patchers as the archers shooting down the enemy’s (bad bacteria) but sparing the allied forces (good bacteria).

If our bodies already have inbuilt immune cells that hold the fort, why do we need to worry about our “gut health’?

Our “good” friendly gut bacteria are like the nurses and doctors that keep the archers on the castle wall in top health. Basically having plenty of “good” bacteria in your gut keeps the “bad” bacteria in check, therefore the Peyer’s Patches can perform their job of protecting you properly. If the enemy is too prolific and start climbing over the fort walls then the archers struggle to do their job. The result? You are more vulnerable to the bad bacteria you pick up from your everyday environment and may find yourself getting sick more often than you’d like!

Our good bacteria also ferment fibre and resistant starch to form a fatty acid called butyrate. Butyrate acts to increase blood flow to the gut wall and provides essential energy to the cells that line your colon—this is all vitally important for the repair and growth of healthy colon cells [3].

Would you agree that a well functioning gut and balance of good and bad bacteria is important for a healthy immune system? Do I hear a resounding “hell yeah?!” Very good. So here are the key steps to support a healthy gut:

1. Probiotics—including food that contains probiotics helps to restore the “good” bacteria in our guts, especially if you’ve been through or are currently taking a round of antibiotics. Many fermented food products such as sauerkraut, kombucha and yoghurt contain probiotics and other by-products that are good for building a healthy gut.

2. Use antibiotics as a last resort—they can be life-saving however unnecessary use can “flush out” our good gut bacteria as well as the pathogenic ones.

3. Hydrate—drinking water helps hydrate us, keeping the bad bacteria propelling through the digestive tract, aiding easy elimination.

4. Eat plenty of fibre, resistant starch and prebiotics—this is A-grade fuel for the good bacteria in your gut. Click here to find out more about prebiotic fibre.

5. Happiness—the gut-brain connection is becoming more and more supported by research as having a strong impact on overall wellbeing. The neural network that connects the two organs is complex and intricate, but scientists are starting to unveil the function of a healthy gut brain connection… more about mood and gut health in a later blog.


[1] Better Health Channel. Immune System, 2018. Available from:

[2] Colquhoun J. Everything you need to know about gut health, 2016. Available from:

[3] Enders G. Gut, the inside story of our body’s most under-rated organ, 2015. Scribe Publications: Carlton North, Australia.



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