What is the microbiome?
There has been a lot of talk recently about the human microbiome. But what exactly is this? The microbiome refers to your gut bacteria or friendly bacteria. It is the collection of trillions of microbes (and includes bacteria, yeasts and viruses) that live in and on the human body. There are about a thousand different bacterial species that live in the mouth, gut and vagina, and on the skin. There are actually more bacterial cells in your body than human cells, and they weight 1-2kg.
A mutually beneficial relationship
While previously we would have thought of bacteria as something bad and harmful, many bacteria are very helpful and are known as symbiotic. This means that the bacteria helps the person in or on whom they live while gaining benefit themselves – a mutually beneficial relationship. Some of the microbes in the microbiome are helpful while some can potentially be harmful. However, as long as most of the bacteria are beneficial and symbiotic, and are in balance, they can coexist without problems.
Why is the microbiome important?
The bacteria in the microbiome have a number of important roles.
Digestion of fibre
Fibre is indigestible. We eat it to help move through the gut and prevent constipation. However, gut bacteria are able to digest or ferment fibre resulting in short-chain fatty acids (SCFAs). The SCFAs feed and nourish the cells lining the gut keeping them healthy.
Regulation of the immune system
The gut microbiome can control how your immune system works. The bacteria are able to communicate with immune cells to control how your body responds to infection.
Protection against disease
A healthy microbiome protects against disease causing or pathogenic bacteria. The symbiotic bacteria are able to prevent pathogenic bacteria from colonising the gut by directly killing them, competing for nutrients and enhancing the immune system. Healthy bacteria can even prevent pathogenic bacteria from sticking to the gut wall, thereby protecting them from damage.
The gut bacteria have the ability to synthesise some vitamins, including B vitamins and vitamin K.
Communication with the brain
More recent research has indicated that the gut microbiome can also have an effect on the brain, which is why the gut has sometimes been referred to as your second brain. This was discussed in more detail in my previous blog.
Protection against chronic diseases
A health gut microbiome may also help protect against chronic diseases such as heart disease and diabetes. For example certain bacteria have been found to produce chemicals from animal products that block arteries while healthy bacteria found in probiotics can help lower cholesterol and reduce the risk of heart disease. The gut microbiome has also been found to play a role in blood sugar control and thus the risk of diabetes.
Poor diversity of the gut microbiome has been associated with weight gain and obesity. In fact, people who are overweight or obese tend to have a less diverse gut microbiome. And certain bacteria have been associated with less visceral fat (belly fat).
How can the microbiome help improve your health?
A lower diversity of gut bacteria is found in people with chronic conditions such as diabetes, inflammatory bowel disease, obesity, psoriatic arthritis and atopic eczema. Most likely this will be the case for many other conditions too. Therefore increasing the diversity of your gut microbiome could help reduce your risk of certain conditions.
Looking after your microbiome
Your diet is the most important influencer of your gut microbiome. There are several ways in which you can help improve your own microbiome.
Eat a wide range of different high-fibre foods including vegetables, fruits, pulses and wholegrains.
Try some fermented foods, for example yoghurt (make sure it’s one without added sugar), kefir, kombucha and sauerkraut.
Avoid sugar and white refined carbohydrates which can help ‘feed’ unfavourable microbes that compete with the healthy bacteria.
As well as avoiding sugar don’t be tempted to replace them with artificial sweeteners. These can increase your blood sugar by stimulating the growth of certain unhealthy bacteria.
Take a probiotic supplement. Probiotics provide live bacteria to help restore your gut microbiome with healthy microbes.
Eat prebiotic foods. These are foods which contain a type of fibre that feeds your healthy bacteria and encourages them to proliferate. They include artichoke, asparagus, oats, bananas and apples.
Include foods which are high in polyphenols. These are plant compound that have a positive effect on the gut microbiome helping to encourage diversity. They include red wine, green tea, dark chocolate, olive oil, berries, cherries, blackcurrants, beans, nuts and wholegrains. Supplements rich in polyphenols are also available.
Limit antibiotics by only taking them when absolutely necessary. Antibiotics not only kill off the bacteria that you want to destroy but also destroy many good bacteria too.
We are already learning how important the gut microbiome is not only to the health of your digestive system but also in terms of your general health. If you look after your gut microbiome, it will look after you. With more research, it is likely that we will discover even more about the importance of this vital part of the body’s ecosystem.
Dr Sharon Pitt is a registered nutritionist at Nutrition First, with 18 years’ experience.
Nutrition First is a small and personal nutrition consultancy providing expert nutrition advice, based on sound scientific evidence.
At Nutrition First we help patients manage their digestive symptoms naturally and look at the connection between digestive health and other body systems. Contact us at Nutrition First to see how we can help you.