There is a distinct chill in the air and winter has made its presence felt. Now is the perfect time to start building up your immune system. But, how exactly do we go about boosting immune health and what impact does our diet really have?

Many factors can influence our immune health. In a previous blog post, I explored how stress affects our immune health. The food that we eat is another major player in the integrity of our immune system and it’s ability to fight off invading pathogens.

Why is the diet so important for immune health?

Our diet is our primary source of essential vitamins, minerals and macronutrients (proteins, fats and carbohydrates). Our immune system — like all other organ systems in the body — requires these nutrients in order to function efficiently. Good quality proteins and fats provide the structural components for building immune cells. Vitamins and minerals enable the immune cells to function optimally. Omega-3 fatty acids (found primarily in fish and seafood) support the immune system by reducing inflammation.

The types of foods that we choose to eat can have a significant impact on our gut microbiome — the population of bacteria and other microbes that reside in our digestive tract. Before I go on and explain how different foods impact our the balance of our gut microbes, I want to tell you more about the role that these little guys have in regards to immune health.

The microbes in our gut aid the digestive process and can enhance the bioavailability and absorption of nutrients from the food we eat. The microbiome also makes up part of our mucosal immune system and provides protective effects in two ways:
1. By interacting directly with pathogens to prevent them from invading at the mucosal surfaces (nasal and sinus passage, throat, lungs, digestive tract).
2. By communicating with the immune system and stimulating its response to invading pathogens.

Healthy microbiome foods

Just like the cells in our body need fuel to function, our microbial population also requires a fuel source. But, rather than just take a cut from its host’s energy intake, these clever microbes utilise carbohydrates (known as prebiotics) that humans cannot digest. Typically, foods that contain prebiotics also provide essential vitamins and minerals, proteins, fibre and healthy fats — all important nutrients for maintaining a healthy immune system.

Prebiotic-rich foods
Vegetables Jerusalem artichokes, chicory, garlic, onion, leek, shallots, spring onion, asparagus, beetroot, fennel bulb, green peas, snow peas, sweetcorn, savoy cabbage
Legumes Chickpeas, lentils, red kidney beans, baked beans, soybeans
Fruits Custard apples, nectarines, white peaches, persimmon, tamarillo, watermelon, rambutan, grapefruit, pomegranate. Dried fruit (eg. dates, figs)
Grains and cereals Barley, rye bread, rye crackers, pasta, gnocchi, couscous, wheat bran, wheat bread, oats
Nuts and seeds Cashews, pistachio nuts, flaxseeds (linseeds)
Other Human breast milk
Nuts and seeds Cashews, pistachio nuts, flaxseeds (linseeds)

This table has been adapted from information on the Monash University website

**If you are new to prebiotic foods, it is a good idea to start slowly when introducing them — our microbes produce gas when breaking down prebiotics. If we overload them, things could get a little windy 💨

The not so good foods

While the prebiotic-rich foods are great for nourishing our microbiome, there are also foods that can be detrimental. The primary culprits include processed foods, excess sugar, and alcohol.

Processed foods often contain poor quality fats and excess sugar, which disrupt our healthy microbial population. In addition, processed foods also generally lack essential nutrients, healthy fats, quality protein, fibre, and prebiotics — all the good stuff that supports our microbiome and immune system.

The excessive intake of sugar not only disrupts the good microbial population but, it can also feed the not-so-great microbes and contribute to inflammation. There is also some research that suggests that high sugar intake also reduces the phagocytic function of white blood cells.
*phagocytosis is a PacMan-like action that white blood cells utilise to gobble up pathogens.

Heavy or chronic intake of alcohol disrupts the balance of our microbiome, and in some case can cause damage to the integrity of our digestive tract. Low to moderate intake of alcohol can definitely be part of a healthy diet, and enjoying your beverage of choice with a meal can reduce potential damage to the gut wall.

What about taking supplements to boost immunity?

As a naturopath, I am quite often asked: “what are the best supplements for boosting immunity?” and my response is almost always “good, quality foods”.

Don’t get me wrong. There is absolutely a place for supporting the immune system with supplements and herbal medicines when needed. However, they cannot replace the value of a nutritious, balanced diet. Healthy eating is not about completely cutting out the not-so-good foods, but rather enjoying them in moderation while loading up on fresh, seasonal whole foods.

I always look to increase specific nutrients through foods first and then supplement to fill any nutritional gaps. In saying that, additional nutrient supplementation during the acute stage of infection can help to alleviate symptoms and reduce the duration of infection.

As for immune-specific herbal medicines, they can do an amazing job in increasing resistance to infection as well a providing additional immune support during acute infections. But again, there is only so much that herbal medicine can contribute if the diet and microbiome are out of kilter — it all comes down to balance.

Are you or your family in need of some naturopathic and nutritional support for your immune health? Find out about my services or book a consultation with me


Sarah Woolner

I’m Sarah — a qualified naturopath and food enthusiast. I am currently practicing on Sydney's Northern Beaches, in Brookvale and Mosman. If you would like to make an appointment please send me an email via the contact page.

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