Gut health is much more than having good digestion and regular bowels. A healthy gut contributes to better health in almost every other organ and system in your body. But how and why? The answer lies in the massive populations of good bacteria that live in your gut – the so called microbiome – and the role of prebiotics and probiotics.

What is the microbiome?

There are trillions of bacteria in your gut. (A trillion? That’s 1,000,000,000,000). It is estimated that there are 30 to 50 times that many little guys living inside your digestive system. Some say there may be 10 times as many bacteria than human cells in the average person. This all sounds a little creepy, but the bacteria in your digestive system are critical for good gut health.

Known collectively as the microbiome, this ecosystem is home to 1–2 kg of these organisms. The bacteria in your gut help you break down food, converting the nutrients into substances your body needs.
However, not all bacteria are our pals. Inside the body, the ‘good’ bacteria keep the ‘bad’ bacteria – the ones that cause disease and change your mood – in check. In a favourable environment they multiply so rapidly that the unhealthy bacteria don’t have space to grow. Luckily, we’re able to improve gut health if it has gone out of kilter.

Where the microbiome originates

You get your gut microbiome from your mother at birth. As you grow up, the world around you affects it too, as does your diet. People from different backgrounds may have vastly different gut bacteria. These differences in gut bacteria globally are so interesting that they’re the subject of numerous medical and genetic research projects. You could say that science is finding more and more truth in what was before just a ‘gut feel’.

So is it all about nutrition, grumpy guts?

What is astounding scientists (and us too) is how many common complaints are linked to imbalances in the microbiome.

Nearly 2500 years ago, Hippocrates, the father of modern medicine, wrote, ‘All disease starts in the gut.’ Yet medical researchers have only recently begun to study the gut/health link, and they’re confirming that the microbiome in your digestive tract plays a huge role in both physical and mental health. Says TV health presenter Dr Michael Mosley, ‘We know, for example, that people who live with depression and people who sleep poorly both have abnormal microbes in the gut.’

Say what?!

Of course there are all sorts of conditions that we now associate with poor gut health. Ulcerative colitis, Crohn’s Disease, Irritable Bowel Syndrome (IBS) – it follows almost intuitively that these conditions can be linked to a healthy symbiotic relationship with our microbiota. And the list of disorders related to gut health is growing at an incredible rate. For example:


We’re no fans of animal testing, but there is some fascinating information emerging from research labs. In one study, bacteria transferred from obese mice into healthy mice caused the healthy mice to become obese. (Strangely, transferring bacteria from the healthy mice to the obese ones did not make them lose weight.) So, as always, be very sceptical of products or diets that promise the world.

The chance of finding out how the human body would react in lab conditions if it were forced into a state of unhealthiness is zero. But we know with certainty that replacing good food with junk food makes everyone unhealthy. Quite simply, following a healthy diet can show reduced signs of inflammation; eating processed foods increases inflammation. The greatest irony? A bad diet, too little exercise and generally feeling poorly are regarded as potential causes of depression (see below).

We are just scratching the surface of gut health research. There are so many questions that need answers: What does it mean to have a healthy range of bacteria? Which bacteria do we need, and how many? Should we all aim to have the same bacteria for good gut health?

There are compelling signs that improving diversity can make a difference – by reducing cravings, or helping the body to cope. ‘Future studies should focus more on how the composition of gut bacteria can be modified to reduce the risk of obesity and associated metabolic diseases and cardiovascular disease,’ says Professor Marju Orho-Melander of the Department of Clinical Sciences at University of Lund in Sweden.

Stress, anxiety and depression

Another particularly cruel test on young rats provides a surprising insight. Two groups were formed. In one group, the youngsters were separated from their mothers. This group showed signs of depression. They moved around less and, when placed under stress – being forced to swim as long as they could – the ‘depressed’ group did not swim as long as the other group. Incredibly, probiotic therapy reduced the signs of stress. It got the poor guys to make an effort to swim harder.

Several other tests confirm that a higher level of beneficial bacteria eases anxiety, and enables you to tolerate an increased amount of stress before your health is impacted.

Some people who are depressed show signs of low levels of inflammation. This simply means that your body feels invaded or under attack. And the body responds by releasing chemicals in defence. These same markers present in depression can be found when people suffer from IBS or damage to the lining of the gut, such as in gut permeability disorders. Chemical messages like these are present when people experience any form of stress – physical, mental or emotional.

Low immunity, chronic fatigue, skin problems and eczema

All of these are on the list of conditions associated with poor gastro-intestinal health.

An interesting fact: Studies show that the balance of bacteria in your gut can be disturbed for up to a year after a course of antibiotics. The obvious conclusion is that every single one of us could get closer to optimal wellness by paying greater attention to what is happening in our internal engine room. Thankfully, many of the things we can do to improve our gut health are simple, inexpensive and taste pretty darn good!

Improving the ‘good’ bacteria in your gut

Take probiotics

The benefits of probiotics for gut health are well publicised. Found in some foods, these ‘good’ bacteria match the ones already in your gut, increasing their numbers and helping keep everything in balance. There are many types of probiotic bacteria. Some strengthen your immune system, others may boost gastrointestinal health (useful if you suffer with conditions such as IBS or leaky gut syndrome). Some probiotics can help ease symptoms of allergies and help with lactose intolerance.

Find probiotics in dairy products like yoghurt and mature cheeses. Check the ingredients list – you’re looking for live cultures of bacteria such as bifidobacteria and lactobacilli. There are billions of probiotics in a single gram of fermented foods, like kimchi, kefir and sauerkraut, and pickled vegetables such as onions and gherkins. But probiotics need feeding too. So you need to add…


You are what you eat. Or more accurately, you are what you feed the huge ecosystem of microbes, including bacteria, in your gut. Only recently making waves in health headlines, prebiotics are non-digestible complex carbohydrates, mainly fibre. These carbs are fermented by colonies of bacteria in the gut and helps to alter the composition of the gut microbiome. ‘Prebiotics act a bit like scattering fertiliser on your lawn,’ says Dr Michael Mosley. ‘They’re vital if you’re looking to maintain good gut health.’

Find prebiotics in foods such as bananas, raw garlic, onions, leeks, raw asparagus, artichokes, soya beans, whole-wheat foods. Slippery elm is an excellent prebiotic supplement as it contains both soluble and insoluble fibre, and is extremely soothing to the digestive tract.


Probiotics can increase the number of good bacteria, and prebiotics feed probiotics. When you combine the two, they form a synbiotic. Synbiotics help probiotics live longer. Create your own synbiotic combinations by combining bananas with yoghurt, stir-fried asparagus with tempeh, or berries with nuts and seeds – smoothie bowl anyone?

Other ways to improve gut health

Cut down on sugar

Refined carbohydrates and processed foods are more likely to encourage the growth of bacteria that are bad for gut health. Instead, tuck into unrefined natural sweeteners, raw organic chocolate and cocoa powder, peanut and other nut butters, maple syrup, honey and fresh medjool dates.

Reduce stress

There’s a close link between the mind and the gut – remember exam-time ‘butterflies’ in your stomach? Get so worried you feel sick? A new area of science, called psychobiotics, is exploring the connection between gut health and the brain.

Hormonal, neuronal and bacterial changes in the bowel are transmitted to the brain via the vagus nerve. So the path to a person’s brain is in fact through the stomach, as the proverb does not go. Here’s some good news: Some bacteria literally produce our feel-good chemicals. Sure, serotonin may have a different job down there, but it’s a pretty pleasing way to imagine your bacterial buddies.


Whatever our state of health, we can all benefit from taking better care of our ‘gut garden’, says Dr Mosley. And we’re not talking the latest ‘superfoods’ here. ‘I think many vegetables are superfoods,’ says Mosley. ‘I think cabbage and beetroot are superfoods. Whether they’re sexy “superfoods” is another matter. But they are absolutely nutrient-packed and tasty, and provide you with elements you may not be getting from the rest of your diet.’

And for a good night’s sleep? Take a slippery elm (such as Flora Force full-spectrum Slippery Elm tablets) with a glass of warm milk at bedtime. Sleep tight!

Acknowledgements & Photo credits

Article compiled for Flora Force by Judy Beyer.


  1. American Microbiome Institute. 2016, Jan. How many bacteria vs human cells are in the body?
  2. Evrensel, A and Ceylan, ME. The gut-brain axis: The missing link in depression. Em>Clinical Psychopharmacology and Neuroscience. 2015 Dec;13(3): 239–244.
  3. Harvard Health Letter. Do gut bacteria inhibit weight loss? Harvard Health School. 2018.
  4. Leaver, Kate. Could it be your gut keeping you awake at night?The Guardian. March 2018.
  5. Mayo Clinic staff. Prebiotics, probiotics and your health. What’s the difference between a probiotic and a prebiotic and why you need them.
  6. Mosley, Michael. The clever guts diet.

Photo credits

  1. Abdomen photo courtesy of silviarita
  2. Yoghurt photo courtesy of RitaE