Eating for real immune support this winter

When winter temperatures plunge, there’s often a spike in the prevalence of colds and flu, but the right diet can provide the immune support your body needs to stay healthy.  

In defence, we typically turn to the latest flu shot, as well as vitamin and mineral supplements in the hopes of giving our immune systems a protective ‘boost’, but one of the most effective ways to support your immune system is through daily nutrition.

 Consistent nourishment

Registered Dietitian and spokesperson for the Association for Dietetics in South Africa (ADSA), Retha Harmse points out that we must keep in mind that our immune system relies on consistent nourishment, not quick fixes.

“Multiple nutrients work together to keep our immune defences strong, reduce inflammation, and help your body recover from illness.

“Therefore, if you want to reduce your risks of succumbing to winter colds and flu, it makes sense to double-down on your focus on daily nutrition as your first and most critical line of defence.”

Retha’s advice for optimal immune support in winter is to focus on variety – a colourful plate including plant and animal food sources, herbs, and spices.

The food matrix

Mpho Tshukudu, another Registered Dietitian and ADSA spokesperson agrees: “A balanced diet made up of whole foods support the immune system because of the concept known as the food matrix effect.”

Mpho explains that nutrients and compounds in foods don’t act alone – they interact with each other and the structure of the food in intricate ways that influence how well our bodies can absorb and use them.

“Eating whole foods improves your digestion, nutritional absorption, and immunological response because you’re consuming a complex variety of bioactive substances, fibre, proteins, fats, and phytonutrients rather than just individual vitamins and minerals.”

“In colder months, when our bodies are under more stress and infection risk is higher, they need to rely on the synergistic effects found in whole foods.”

An example of this is that vitamin C in foods such as guavas and oranges is effective for your immune system because of the surrounding matrix of fibre, phytonutrients and other nutrients that improve its absorption and usage.

Getting more nutrients

This highlights why what you eat in winter matters – while our immune system is at work throughout our body, 70% of immune cells are in our gut.

While you may need to use supplements to fill specific nutritional gaps due to illness, food allergies or digestive intolerances, it’s important to note that they cannot replicate the foundation of a consistent, nutrient-dense diet.

Synching with nature by eating seasonally is an important way of optimising immune support. In the winter months, the fresh produce provides so much of what we need to support and protect our bodies.

For instance, there’s a natural abundance at this time of year of fruit and vegetables rich in vitamins A and C.

Mpho explains that vitamin A helps the body defend against viruses and bacteria. She says,

“It occurs as beta-carotene in seasonal vegetables such as orange-fleshed sweet potatoes, pumpkins, butternut and dark leafy greens like morogo or spinach and kale. Winter is also the season for citrus fruits like naartjies, oranges, lemons, and grapefruits which, like guavas, are particularly rich in Vitamin C. This significant micronutrient supports the immune system in fighting off infections and reducing the severity of colds so that they do not develop into more serious respiratory illnesses.” 

What is important to remember is to eat a variety of fresh, uncooked and cooked vegetables and fruits, as both raw and cooked vegetables offer unique benefits. 

Gut-immune connection

Retha reminds us that gut health is a long game. Consistency and variety, not strict rules or quick interventions, lead to the best outcomes.

Retha’s top tips to support gut health in winter include:

1. Increase fibre-rich foods: “Fibre is food for your gut bacteria. Include legumes such as lentils, chickpeas, and beans; whole grains such as oats and brown rice; fruits such as apples, pears, and bananas; and vegetables such as broccoli, carrots, and spinach.”
2. Choose fermented foods regularly: “These contain probiotics which are beneficial bacteria. Add amasi, maas, live yoghurt, sauerkraut, kimchi, or kefir to your diet several times a week.”
3. Rotate your plant foods: “Try to eat at least 30 different plant foods per week. This supports a greater diversity of the beneficial bacteria in your gut which is linked to better health.”
4. Limit ultra-processed foods: “These often contain additives, refined sugar, and are low in fibre – all of which disrupt the gut barrier and feed inflammatory microbes.”
5. Stay hydrated: “Water is essential for digestion, the gut lining, and microbiome balance. Aim for 6–8 glasses daily, or more in dry winter conditions.”