The bugs within us – the human microbiome

Would you be surprised to know that you are home to over a trillion microorganisms? If that number is too big to grasp, that is over 10 times the number of cells in your body and weighs around 2 to 3 pounds, depending on your body weight. Before you say ‘Yikes,’ let me also tell you that this collection of microorganisms or microbiome, as it is called in scientific jargon, is vital for your good health. Indeed, if not for the microbiome, you will most likely die rather quickly.

The microbiome refers to the collection of microorganisms including bacteria, viruses, fungi, and protozoa that live on and inside the human body, and play important roles in maintaining human health, including aiding in digestion, strengthening the immune system, and helping to prevent the growth of harmful pathogens. Imbalances in the microbiome, known as dysbiosis, have been linked to a variety of health problems, including inflammatory bowel disease, obesity, certain types of cancer, and mental disorders such as depression and anxiety.

Here are some examples of how the microbiome affects our health:

Digestion: The microbiome helps break down food, absorb nutrients, and produce short-chain fatty acids that nourish the gut lining. Imbalances in the gut microbiome can lead to digestive disorders such as inflammatory bowel disease and irritable bowel syndrome.

Immune system: The microbiome helps to train and regulate the immune system. An imbalance in the microbiome can lead to an overactive or underactive immune response, which can increase the risk of infections and allergies.

Metabolism: The microbiome helps to regulate metabolism and energy storage. An imbalance in the microbiome can lead to obesity and metabolic disorders, such as diabetes.

Mental health: The microbiome can affect the production and metabolism of neurotransmitters, which are chemicals that carry signals in the brain and play a role in mood regulation. The gut-brain axis, a communication pathway that connects the gut and the brain, modulates our emotional and cognitive processes. It is composed of the enteric nervous system, which is in the gut, and the central nervous system, which includes the brain and the spinal cord. The gut-brain axis is bidirectional, meaning that information can travel in both directions between the gut and the brain.

The gut-brain axis handles the modulation of emotional and cognitive processes, including mood, anxiety, and stress response. The gut microbiome also plays an important role in this communication by producing molecules that can act on the brain and affect the behaviour, for example, gut bacteria can produce neurotransmitters such as serotonin, dopamine and GABA, that are involved in regulating mood and anxiety. Research has shown that the gut-brain axis is involved in the development of several disorders such as depression, anxiety, irritable bowel syndrome

(IBS) and functional gastrointestinal disorders (FGID), and in the pathogenesis of these disorders.

The gut-brain axis is also involved in regulating appetite and satiety, food intake, and energy balance. It is a complex and dynamic system, and more research is needed to fully understand how it works and how to effectively target it to treat various disorders.

Maintaining a healthy gut microbiome is important for maintaining overall health, including mental wellbeing. The gut microbiome also produces molecules such as short-chain fatty acids, that can regulate the immune response and also modulate the gut-brain axis. Studies have found that changes in the gut microbiome are associated with mental health conditions, such as depression, anxiety, and autism.

Cardiovascular health: The gut microbiome has been linked to cardiovascular health by affecting the levels of lipoproteins (cholesterol and triglycerides) and blood pressure.

Skin health: The skin microbiome helps to protect the skin from harmful pathogens and to maintain the skin barrier function. An imbalance in the skin microbiome can lead to skin conditions such as eczema, psoriasis, and acne.

Respiratory health: The respiratory microbiome plays a role in the health of the respiratory system; it helps to protect the lungs from harmful pathogens and to modulate the immune response. An imbalance in the respiratory microbiome can lead to respiratory conditions such as asthma and COPD.

How you can help maintain a healthy microbiome.

Eat a varied and balanced diet: A diet rich in fruits, vegetables, whole grains, and fermented foods promotes the growth of beneficial microorganisms in the gut. Avoiding processed foods and added sugars helps.

Most diets recommended in books are more suitable for western countries so here are some local foods that are beneficial for a healthy microbiome: Green leafy vegetables are abundant in Sri Lanka and are used as condiments (rampe and curry leaves), as a porridge or ‘kola kende’ or finely chopped as a ‘mallung’. Green leaves contain beneficial compounds, such as antioxidants and polyphenols, which can help to promote a healthy gut microbiome. These compounds have been shown to have anti-inflammatory and antimicrobial properties, which can help to protect against harmful bacteria and promote the growth of beneficial gut bacteria. Green leaves are moreover, an excellent source of dietary fibre, which is important for maintaining a healthy gut microbiome. Eating a diet rich in green leaves may also help to improve gut motility and regularity, further supporting the health of the gut microbiome.

Tea, especially green tea, has several benefits on the gut microbiome. The polyphenols in green tea can help to promote the growth of beneficial gut bacteria and reduce the growth of harmful bacteria. Green tea polyphenols have also been found to have antiinflammatory effects, which may help to reduce inflammation in the gut and promote gut health. Theanine, an amino acid found in green tea, is also known to have relaxing effects on the gut, which may help to improve gut motility and regularity. Drinking tea reduces the risk of gut-related disorders such as inflammatory bowel disease and colon cancer. Unfortunately, our habit of mixing our tea with loads of sugar and milk negates most of these benefits.

Take probiotics: Probiotics are live microorganisms that help to restore balance to the gut microbiome. They can be found in fermented foods such as yogurt and kefir, as well as in supplements.

Avoid taking antibiotics unnecessarily: Antibiotics kill beneficial microorganisms in the gut, leading to dysbiosis. If antibiotics are necessary, consider taking a probiotic supplement to help restore the balance of the gut microbiome.

Exercise regularly: Regular physical activity has a positive impact on the gut microbiome.

Practise good hygiene: Regular hand washing and keeping a clean living environment prevents the growth of harmful pathogens in the gut.

Manage stress: Chronic stress has a negative impact on the gut microbiome, hence managing stress through meditation, yoga, or other relaxation techniques, helps to promote a healthy microbiome.

Individual microbiomes vary, and what works for one person may not work for another. It is important to monitor and evaluate the effectiveness of these methods and make adjustments accordingly.

If you like to read up more, I would recommend “The Diet Myth: Why the Secret to Health and Weight Loss is Already in Your Gut” by Tim Spector, a professor of genetic epidemiology at King’s College London. He explains how different food and lifestyle choices can affect the balance of gut bacteria, and how this, in turn can affect our health and weight, presenting the latest research on the gut microbiome, and how it can be harnessed to improve health and prevent disease.

Eating a varied and balanced diet, taking probiotics, avoiding antibiotics, exercising regularly, practising good hygiene, and managing stress are all important steps to maintaining a healthy microbiome. By taking care of our gut, we can improve our overall health and well-being.