Immunity Starts in Your Gut

Winter often sends us searching for ways to avoid the next cold. From vitamin C tablets to immune-boosting supplements, there's no shortage of products promising to keep us healthy. But one of the most important places to support your immune system isn't found in the supplement aisle at all: it's your gut.

Around 70% of your immune cells are found in and around your gut, making it one of the largest immune organs in your body. This means looking after your gut isn't just important for digestion. It also plays a key role in helping your immune system do its job.

So, how are your gut and immune system connected?

Your digestive tract is home to trillions of microbes, collectively known as the gut microbiome. These microbes aren't just passive passengers.

They constantly communicate with your immune system, helping it recognise harmful bacteria and viruses while learning to tolerate harmless substances like food and beneficial microbes. This balance helps your immune system respond appropriately when it needs to.

When your gut microbiome is healthy and diverse, it helps strengthen this barrier, supports the production of beneficial compounds called short-chain fatty acids, and contributes to a well-functioning immune system.

Feed your gut microbes

One of the best ways to support both your gut and your immune system is by eating plenty of fibre.

Unlike us, your gut bacteria love fibre. They ferment it to produce short-chain fatty acids, which help nourish the cells lining your bowel, support the gut barrier and play an important role in immune health.

Aim to include a wide variety of plant foods across the week, including:

• Vegetables
• Fruit
• Wholegrains
• Legumes, such as beans, chickpeas and lentils
• Nuts and seeds

Rather than looking for one "immune-boosting" food, focus on diversity. Different plants feed different gut microbes, and a more diverse microbiome is associated with better overall health. Aim to "eat the rainbow" across the week. Different coloured plant foods contain different fibres and beneficial plant compounds, helping nourish a wider range of gut microbes!

Don't forget fermented foods

Fermented foods containing live cultures can also help support a healthy gut microbiome.

Foods such as yoghurt, kefir, kimchi and sauerkraut can introduce beneficial microbes to your gut and are an easy way to add more variety to your diet. While they aren't essential, they can be a helpful addition alongside a fibre-rich eating pattern.

What about vitamin C?

Vitamin C often gets the spotlight during cold and flu season, but it's important to know what it can and can't do.

Research shows that regularly eating vitamin C-rich foods won't prevent most people from catching a cold. However, it may reduce the duration of symptoms by around half a day.

Rather than relying on supplements when you feel a scratchy throat coming on, focus on consistently eating a balanced diet that naturally provides vitamin C from foods such as kiwifruit, citrus fruits, capsicum, strawberries and broccoli. 

Other nutrients that support your immune system

While no single nutrient can "boost" your immune system, several nutrients help it function normally, including:

• Protein, needed to build immune cells and antibodies.
• Zinc, which supports normal immune function.
• Vitamin D, which helps regulate immune responses.

The good news is that these nutrients can all be found in everyday foods like lean meat, seafood, eggs, dairy, tofu, legumes, nuts and seeds.

It's about more than food

Your immune system doesn't rely on nutrition alone.

Nutrition is only one piece of the puzzle. Prioritising sleep, staying physically active, managing stress and keeping hydrated all help support a healthy immune system.

A Final Word

There isn't one food, drink or supplement that can guarantee you won't get sick.

Rather than chasing the latest immune supplement each winter, focus on the habits that matter all year round. Filling your plate with a wide variety of plant foods, including enough protein and other essential nutrients, and looking after your gut won't guarantee you never get sick, but it will help give your immune system the support it needs to function at its best.

Need some inspiration? Check out our Immune Boosting Meals graphic below for simple meal ideas that nourish your gut while providing the nutrients your immune system relies on.