Introduction to Gut Bacteria

What is the gut microbiota?

Your gut microbiota refers to all of the microorganisms (e.g. bacteria) that live within your gut. In fact, the largest population of microorganisms within the body live within the bowel.

The bacteria/microorganisms that live within your gut is completely unique to each individual. The human gut microbiota consists of over 100 trillion microorganisms, and weighs around 200g, around the same as an adult hamster!

Why is it so important?

Your microbiota has many functions, including defending against harmful microorganisms and digesting dietary fibre, that humans are unable to digest. Your microbiota also ease the absorption of some essential vitamins, and can even affect your mental health.

Early research suggests that some of the earliest changes that lead to Parkinson’s disease may actually begin with the gut microbiota. This recent discovery only highlights just how much we’re yet to discover about the microorganisms that occupy our gut, and the connection to our brain.

What influences your gut microbiota?

We can influence our gut microbiota, but only to an extent. There are many factors at play, and some begin before you even leave the womb.

Some factors we can influence:

• Feeding methods, such as breast milk, artificial milk and introduction of solid food
• Any medication such as antibiotics, acid suppressants and more
• Dietary habits and the way food is cooked
• Environment and lifestyle factors e.g. rural vs urban and exercise
• Weight gain

Some factors we can’t influence:

• Genetics
• Gestational age; whether you were born preterm vs. full-term
• Delivery mode; vaginal delivery vs. C-section
• Ageing

What can I do to help my gut microbiota thrive?

The food you eat is the main fuel for your gut microbes. A review of the research literature suggests that diet can modify your microbes, this in turn has a profound impact on your overall health. Moreover, some studies have shown that gut microbiota composition is different in conditions such as type 2 diabetes, obesity, and inflammatory bowel diseases.

Some of the food that you eat does not absorb inside your body (fibre), but feeds the trillions of microorganisms that live in your gut. This part of the fibre that feeds these microbes is called a prebiotic (literally meaning ‘before living organisms). If we consider our microbes as our gut garden, then the prebiotic is the fertiliser that helps to nourish our gut microbes.

Food sources of these prebiotics are plant foods. Some foods containing larger amount of prebiotics include: artichokes, asparagus, chicory, bananas, berries, tomatoes, garlic, onions, legumes, green vegetables and wholegrain cereals.

Fermented foods (frequently termed probiotics) are usually added to yoghurts, juices or taken as food supplements and are often described as ‘good’ bacteria. These foods are not harmful for most people with a healthy immune system, although the overall evidence that they are helpful in modifying the gut microbiome is inconclusive. If you have a digestive disease, you should talk to your doctor or dietitian before trying them.