When it comes to maintaining good health, the immune system is our most precious asset; Incredibly sophisticated and astonishingly complex. 
 
Following the impact of COVID one thing’s become very apparent-we need a resilient immune system. A well-functioning immune system not only helps protect us from infective organisms like viruses and bacteria though. We also rely on this complex immune network to protect us from our own malfunctioning cells. 
 
Roughly 70% of our immune system is located in our gut and our immune systems are completely unique to us, just like our fingerprints. We all inherit a set of coded immunity genes and although these codes can’t be changed, the expression of these codes is very much something that can be managed. By manipulating this genetic code through diet and lifestyle choices we can help support and maintain our immune systems. Our gut microbiota, diets, sleep, stress and physical activity levels, all play a part. 

How does the gut microbiota help our immune systems? 

The gut microbiota is the name given to the trillions of microbes living in our gut and recent studies have shown that the types and diversity of these gut bugs play a huge role in immunity. Scientists are now referring to the gut microbiota as a ‘new organ’ because it appears to have such a significant impact on our biological systems. 

Where do the gut bugs live? 

We have gut microbes throughout our whole gut but the majority live in the small section of the bowel called the large intestine. It is here where the gut bugs exert their impact on our health. 

What do these trillions of bugs actually do? 

They are responsible for many things including educating our immune system, digesting food, making nutrients such as B vitamins, making beneficial chemicals like antifungals and antibiotics to fight invading organisms, neurotransmitters like serotonin and also chemicals called short chain fatty acids. Short chain fatty acids are really important because it is the food for the cells of our gut lining-much needed food for the maintenance of a healthy, well-functioning gut. 

What does the gut lining do? 

The gut lining is a very thin barrier which is actually just one cell thick to allow easy transport of all the beneficial products of digestion to pass into the bloodstream for transport around the body. If this barrier isn’t functioning well it can become a bit ‘leaky’ and allow harmful microbes or bits of unwanted food to pass into our blood system. This leads to a localised immune response and inflammation. It’s relentless work for our immune cells. They are constantly on guard, assessing whether things passing through this lining are friend or foe. When the immune system is continuously dealing with invading foes the resulting excessive, often chronic inflammation affects the whole immune system and leads to the development of chronic disease. 
 
A healthy gut microbiota feeds our gut lining to help maintain healthy barrier helps make helpful nutrients and helps fight invading pathogens. All these functions help our immune system. But how do we make sure we have the right types of gut bugs? 

What does a healthy gut microbiota look like? 

You may have heard of good and bad gut bugs. Some bugs are very beneficial to health and some are associated with disease but it’s actually having a diverse mix of bugs that’s been found to be most important. A diverse gut microbiota is needed to be really healthy. If you think beautiful English country garden bursting with colourful varied perennials rather than arid scrubland with just a few species you’ll get the picture. 

How do we maintain a diverse gut microbiota? 

Our sleep our levels of physical activity and stress levels all affect gut bug diversity but it is the food we eat that has the biggest impact. Taking the garden analogy, by feeding your perennial border it will mean the beautiful colourful flowers will flourish and the weeds will be left with little room to grow. The same thing happens in the gut. Food choice will encourage the certain colonies to flourish and good food choice improves diversity. 

Which foods are best for improving diversity? Prebiotic and Probiotic foods. 

Prebiotic is a term to describe the foods the microbes like to feed on. Healthy gut bug food if you like. These foods are the most important foods to include in your diet and the main drivers of good gut health. 
 
The term probiotic refers to large amounts of helpful live bacteria found in fermented foods and supplements that are beneficial to health. At the moment the jury is out on whether these live bugs actually colonise the gut after ingestion but even if they just end up passing through they are believed to exert all the beneficial effects of the good host bugs before being pooped out. 
 
Which foods are prebiotic? 
 
High fibre complex plant foods. Each plant-based food group contains different fibres and getting a variety of different fibres is best for diversity and immune health. Food groups include legumes, wholegrains, vegetables, fruits, nuts and seeds. Colourful fruits and vegetables are high in plant chemicals called polyphenols and are great prebiotics. Seasonal foods are also more nutrient dense. 
 
Great examples include apricots, artichokes, asparagus, beetroot, pomegranates, garlic, oats, wheat bran, leeks, Brussels sprouts, almonds, pistachios, dates, chickpeas, beans, teas and coffee, dark chocolate and red wine. 
 
Which foods are probiotic? 
 
Good examples include live yogurts, kefir, kombucha, unpasteurised cheeses, unpasteurised sauerkraut and kimchi. 
 
Try to include at least one portion of these foods a day.If you struggle with these fermented foods you can use probiotic supplements and there are many good quality products available . 
 
Foods to avoid 
 
Eating a diet high in sugar or high fat processed foods can have a really negative impact on gut bug diversity so avoid these whenever possible. 
 
Summary 
 
So yes, the gut microbiota really are important for a well-functioning immune system. To help maintain a well functioning immune system each time you reach for your fork ask yourself,’ will my gut bugs like this?’ 
 
Top tips for eating to support gut and immune health 
 
Eat whole foods-think natural, wholegrains and pulses.  
Eat variety. Diversity of plant foods is the goal. Aim for about 8 different plant portions a day possible and 30 each week.  
Eat a rainbow. Coloured fruits and vegetables contain different beneficial nutrients and fibres.  
Eat seasonally if possible as foods tend to be richer in nutrients.  
Eat a portion of fermented food each day.  
Avoid processed foods
Tagged as: Gut health
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