The gut microbiome: explained

The gut microbiome refers to the diverse community of microorganisms residing in the digestive tract. It plays a crucial role in digestion, immune function, and metabolism. Imbalances in the microbiome can lead to digestive disorders, inflammation, and compromised overall health, highlighting its significance for gut health. Leading medical weight loss specialist Dr Philip Bazire explains everything you need to know.

What is the gut microbiome?

The gut microbiome is a community of around 100 trillion microbes (bacteria, viruses, fungi, protozoa) that live in the small and large bowel. The number of bacteria, the types that are present and the range of different types (diversity) are all important factors that determine the health of our gut microbiome. While research primarily focuses on the colon, understanding microbes in the small intestine is an increasing area of research.

Gut microbes utilise nutrients from food, producing enzymes that aid digestion and create by-products like gases and beneficial chemicals. These chemicals, including vitamins and fatty acids, provide energy, support metabolic functions, and enable communication between the gut microbiome, immune system, and nervous system via the gut-brain axis.

How does diet affect the gut microbiome?

Our gut microbiome, influenced by diet, medications like antibiotics, pesticides, heavy metals, stress levels, and diseases, plays a vital role in health. Greater microbial diversity improves gut function and resilience. As our diet affects microbial diversity, a varied diet is crucial. Compared to the past, today's Western diet is less diverse, impacting gut microbial diversity negatively. Ultra-processed foods lack prebiotic components, containing high fat and sugar content, further disrupting the gut microbiome. This leads to detrimental changes in microbial composition, affecting overall health.

What are the best foods to promote a healthy gut microbiome?

There are two ways we can help our gut microbiome through our diet. One is by eating foods that contain microbes useful to the gut (probiotics), the other is by eating foods that specifically feed the microbes already present in our gut (prebiotics).

The probiotics are mainly fermented foods, such as kefir, kimchi, tempeh, sauerkraut and yoghurt with live cultures. Prebiotics are certain types of plant fibre that cannot be digested by the human gut but that can be used by the gut microbes. Given the diversity of the gut microbiome, we need a wide variety of fibres to be able to feed all of them.

The following types of fibre considered to be most beneficial as prebiotics:

• Beta glucans, found especially in oats and barley
• Inulin and oligosaccharides, found in asparagus, garlic, leeks, onions, chicory root and Jerusalem artichoke
• Pectins, found in fruit, especially apples, citrus fruit and berries, and in some vegetables, especially carrots, tomatoes, green beans and potatoes
• Resistant starch, found in legumes, green bananas, cold cooked pasta and potatoes.

Can gut microbiome imbalances contribute to weight gain?

The gut microbiome has been found to contribute to weight gain in three ways:

• The chemical byproducts of microbial metabolism are involved in signalling to the appetite centres in the brain via the gut-brain axis. This can work both ways, increasing or decreasing our appetite, Due to this, it is an active area of research in weight management.
• Gut microbial changes driven by a poor diet facilitate calorie extraction from the food we eat, and promote the storage of those calories as fat.
• An unhealthy gut microbiome exposes the lining of the gut to damage, leading to chronic inflammation, which has been shown to increase our appetite.

How can I improve my gut health through diet?

Caring for our gut microbiome is crucial for weight management and disease prevention. While our microbiome is established in early childhood, its composition can shift over time, making it challenging to introduce new microbes through probiotics. Instead, focusing on feeding existing microbes with prebiotic-rich foods, especially diverse plant fibres, is key for maintaining gut health. Plant-based foods also provide polyphenols, supporting beneficial microbes and reducing harmful ones, with added antioxidant and anti-inflammatory benefits.

To optimise gut health, you should consume a variety of fruits, vegetables, nuts, seeds, legumes, and spices. While dark chocolate and red wine offer polyphenols, moderation is advised. Prioritising these dietary choices promotes a thriving gut microbiome, enhancing overall well-being.

Are there any supplements or probiotics that support a healthy gut microbiome?

Probiotics are live microbes in foods or supplements that support gut health by aiding resident organisms, fortifying the gut wall, and interacting with immune cells. They are beneficial post-illness or antibiotic therapy, aiding the gut microbiome's recovery. Fermented foods like kefir, kimchi, and sauerkraut, along with yoghurts, provide long-term support and natural prebiotics. Prebiotic supplements offer similar benefits but lack the diverse nutrients of natural sources like fruits and vegetables. The natural food matrix enhances nutrient absorption and utilisation in the gut, potentially influencing their effectiveness compared to isolated supplements.

The gut microbiome plays a crucial role in our overall health and can impact weight management. Inclusion of a wide variety of foods that contain nutrients (fibres) that feed the microbes will increase microbial diversity and favour the “good” microbes over the “bad” ones. A diverse microbiome is beneficial to health and weight stability.

If you would like to learn more about gut microbiome and would like to book a consultation with Dr Ba ire, do not hesitate to do so by visiting his Top Doctors profile today.

Refs:

Gut microbiota: a non-target victim of pesticide-induced toxicity. Gut Microbes. 2023; 15(1). doi: 10.1080/19490976.2023.2187578

A healthy gastrointestinal microbiome is dependent on dietary diversity. Molecular Metabolism Volume 5, Issue 5, May 2016, Pages 317-320. https://doi.org/10.1016/j.molmet.2016.02.005

Functions of Gut Microbiota Metabolites, Current Status and Future Perspectives. Aging Dis. 2022 Jul 11; 13(4): 1106–1126. doi: 10.14336/AD.2022.0104

20 Things you Didn’t Know About the Human gut Microbiome. J Cardiovasc Nurs. 2014 ; 29(6): 479–481. doi:10.1097/JCN.0000000000000166.

Gut Microbiota and Its Possible Relationship With Obesity. Mayo Clinic Proceedings, Volume 83, ISSUE 4, P460-469, April 2008. DOI: https://doi.org/10.4065/83.4.46