As the temperatures drop and coughs, colds and scratchy throats start circulating, most people reach for vitamin C tablets.
But one of the most powerful defences you have is actually inside you already, your gut.
Often called the body’s “second brain”, the gut does far more than digest food. It plays a central role in keeping your immune system strong, responsive and resilient. Supporting it now could make all the difference in how well you fend off winter bugs.
Why the Gut Matters for Immunity
Around 70–80% of your immune system lives in the gut. This is where your body decides what’s friend or foe, builds antibodies and trains immune cells to respond appropriately.
A healthy gut microbiome, the trillions of bacteria living in your digestive tract, helps to:
- Regulate inflammation, preventing overreactions that leave you feeling run-down
- Block pathogens, acting as a physical and chemical barrier against harmful microbes
- Support antibody production, including IgA, which protects your nose, throat and lungs
- Break down nutrients, such as zinc and vitamins A, D and B, which fuel immune function
When your gut flora is diverse and balanced, your immune system is better prepared to respond to seasonal threats.
How Gut Imbalances Make You More Vulnerable
An imbalanced microbiome, often caused by stress, poor diet, too little fibre, antibiotics or lack of sleep, can weaken your defences. This might show up as:
- More frequent colds
- Slower recovery
- Digestive discomfort
- Fatigue
- Increased inflammation
Essentially, when the gut is struggling, your immune system struggles too.
Ways to Strengthen Gut Health This Winter
The good news? Small daily habits can dramatically strengthen both your gut and your immunity.
1. Load Up on Fibre and Polyphenols
Your beneficial gut bacteria thrive on the diverse fibres found in vegetables, fruits, legumes, nuts and seeds. Aim for a variety of colours, each one feeds different microbes.
Polyphenols, found in berries, green tea, cocoa, olives, herbs and colourful plants, are also powerful allies for gut health. Because they aren’t fully absorbed in the small intestine, they reach the colon and act as fuel for beneficial bacteria. As these microbes break polyphenols down, they produce anti-inflammatory compounds that strengthen the gut lining and support a balanced microbiome, ultimately boosting overall immunity.
2. Add Fermented Foods
Foods like kefir, yoghurt with live cultures, sauerkraut, kimchi, miso and kombucha introduce helpful bacteria and support greater microbial diversity.
3. Consider Probiotics
A probiotic can help support microbial balance. I developed my Biome 9 over 20 years of seeing what works best with my patients.
4. Avoid Excess Sugar and Ultra-Processed Foods
Ultra-processed foods can disrupt the balance of gut bacteria, while sugar feeds the less beneficial strains, potentially inflaming the gut lining and weakening immunity.
5. Prioritise Sleep
Lack of sleep disrupts the microbiome and increases susceptibility to infections. Aim for 7–9 hours each night.
6. Stay Hydrated
Water supports the gut lining and helps keep digestion moving, both essential for a healthy microbiome. Ideally choose well-filtered water and avoid plastic bottles where possible!
The Bottom Line
A strong immune system starts with a strong gut. By nourishing your microbiome with whole foods, good sleep and healthy daily habits, you support your natural defence against seasonal illnesses.
