Skip to main content

In Australia, we have just started our winter season, which means increased sales of cold and flu medicine, more work absenteeism and in some states,  we have even run out of supplies of the flu vaccine!

Whilst the cold air and frosty weather would have some impact on our health, emerging science is showing a greater association between food and the gut for overall immunity and there is certainly more truth than ever in the age old saying that ‘we are what we eat.’

All the food that we eat and drink passes through our GI tract, which is lined with mucous that contains millions of bacteria, commonly known as the gut microbiome.  A healthy person will have a balanced microbiome with diverse types of bacteria, allowing the body to harvest nutrients from food, whilst at the same time reacting to harmful pathogens that can cause illness and disease.

Illness, stress, overuse of antibiotics are some of the factors that can result in an unbalanced gut microbiome, which can lead to gut inflammation and decreased ability to fight infection and increased illness. Diet plays a critical role in supporting good immunity via a balanced microbiome, especially fermentable fibres , which encourage growth of healthy bacteria. This is known as the “prebiotic effect” when these fibres are selectively utilised by the host microorganism to confer a health benefit. 1

A typical Western diet of high fat, high protein processed foods is low in these fermentable fibres, which can result in an imbalance of bacteria within the gut. A lack of sufficient fermentable fibres to feed the growth of healthy bacteria results in a decline in overall bacterial diversity, decreased gut cell wall integrity and increased gut permeability (often referred to as ‘leaky gut syndrome’) . As a result, specific immune pathways are affected, leading to greater increase of illness and disease.

To combat illness and disease, we need to let food be our medicine. We need to feed the trillions of bacteria with prebiotic fibres from foods such as fruits, vegetables, legumes and whole grains. When the bacteria break down these fibres through fermentation, short chain fatty acids (acetate, propionate, butyrate) are produced, which nourish the lining of the cell wall and help to maintain immunity.

There is increasing research into prebiotic fibres and stimulation of the immune system. It is possible that the effect is indirect, that is it is mediated through the increase in healthy bacteria such as lactobacillus and bifidobacillus. Or it is possible that the prebiotics may act directly on the immune system. The gut contains the largest pool of immune cells in the body which are separated only by a single layer of cells from the gut lumen and so the dietary components might be able to act directly on these immune cells.

One thing is for certain though, the path to illness or good health goes directly via our gut. So whilst the flu shot may help stave off winter illness, make sure you look after your gut at the same time!

Yours in good health this winter,





Teri Lichtenstein (APD)
The Healthy Grain Brand Ambassador




Intended as general advice only. Consult your health care professional to discuss any specific concerns.

Leave a Reply