SARAH DI LORENZO: How to look after your gut feelings for stronger immunity and better mood

Our gut health plays a very big role in immunity and mental wellbeing.

Taking care of our gut can help to lower our risk of colds, flu and even support mood and cognitive function. With all the recent research about gut health and our awareness of our incredible microbiome — the community of microbes in our digestive tract — there is ample evidence supporting the role our gut plays in our immunity and mental health.

Think about it — 70 per cent of our immune cells are in our intestinal tract. The immune cells are amongst trillions of microbes in our gut, all these microbes are differentiating between what could be food particles, good bacteria or invaders.

Beneficial microbes help train the immune response, teaching them to recognise threats and respond.

When the gut is healthy so is our immunity. On the other hand, when the microbes are disrupted, otherwise known as dysbiosis, the body’s immune response is weak, making people more susceptible to respiratory infections, colds and flu. Diet, stress, antibiotics and illness can also throw the gut out of balance, weakening defences.

There is some interesting recent research on the gut–lung axis. This has shown that changes in the gut microorganisms can have an influence on immunity in the lungs and airways. Again stress, antibiotics and poor diet that impacts microbiota can increase risk of respiratory illness, flu and asthma.

The key is to be eating fibre-rich foods and fermented products such as yoghurt, kimchi, sauerkraut, miso, kombucha, tempeh and tofu to feed protective microbes and increase production of short-chain fatty acids such as butyrate that are important for our overall health, lowering risk of chronic disease and improving our immunity.

The diet needs to be full of whole foods with lots of diversity to feed all of those beneficial microbes to support our immune system. My tip is to try and eat 30 different plant foods per week. It is easier than you think.

The gut–brain axis refers to the communication between the gut microorganisms and the brain and it is constant.

It is co-ordinated by hormonal, neural and immune signals. Research shows those with depression, stress related illness and anxiety have a disrupted microbiota.

People who have diversity in their gut bacteria have been linked to having lower incidence of anxiety and depression. When people have been treated with probiotics for mental health there has been reported improvement in some clinical trials.

The gut has a major role in the production of serotonin and dopamine. These neurotransmitters play a huge role especially in mood but also in digestion.

About 90 per cent of serotonin is produced in the gut. Serotonin makes us feel good. Our gut microbes can influence how much serotonin is produced by breaking down dietary tryptophan and signalling gut cells to release serotonin. Serotonin signals the brain via the vagus nerve to affect mood and anxiety.

When it comes to feel-good dopamine, nearly half of the body’s dopamine is made in the gut using the amino acids tyrosine and phenylalanine found in protein-rich foods such as soy, beef, fish, tofu and eggs.

Dopamine in the gut can impact digestion, movement of food and stomach acid, but also sends signals that indirectly influence brain motivation, reward and mood through gut–brain communication pathways.

When our gut bacteria changes it will influence serotonin and dopamine and in turn may influence mood, gut health and stress response. The best course of action is to make sure you have a good diverse range of plant foods in the diet such as fruit, vegetables, whole grains and legumes.

Make sure you are having fermented foods daily. Start by adding sauerkraut as a side to your salads or drinking a miso soup instead of an extra coffee or tea. Remove all junk foods, excess sugar and processed foods from your diet and for extra support, consider a good quality probiotic.

Taking care of your gut health through diet, lifestyle and probiotics can support immunity, lowering risk of colds, flu and respiratory infections, while at the same time enhancing mental health.