From the moment we are born, during vaginal birth, our body is populated by millions of microscopic creatures. These creatures – thousands of species of bacteria, viruses, and fungi (also known as the microbiota) – assemble the human Microbiome. These tiny beings, invisible to the naked eye, reside throughout our outer cell layer – from the skin protecting our exterior to our gastrointestinal system and lungs.
In recent years, research exploring the Microbiome and its composition has been accelerating and expanding. Since 2003, almost 13,000 articles about it were published, which make more than 80% of the articles ever written about it. It has revealed momentous discoveries, such as that the Microbiome could affect the onset of diabetes, autoimmune diseases, allergies, cardiovascular diseases, mental illness, neurodegenerative diseases, and even cancer. However, researchers still struggle to explain how these effects occur.
The organisms in the Microbiome maintain a symbiotic relationship with the human body: they protect it, and in return receive good environmental conditions and steady nutrition. About 25% of the Microbiome community is determined genetically. For instance, a person with a naturally hyperacidic stomach and oesophagus, will not be a good host to some bacteria. The rest of the Microbiome is affected by our nutrition, health and physical surroundings (the air we breathe, the water we drink). An extreme diet, for instance, could influence up to 40% of the gastrointestinal Microbiome community by depriving bacteria of nutrition necessary for it to live.
Contrary to popular belief, consumption of beneficial bacteria (“probiotics”), whether by medical supplements or by eating foods such as pickles and yogurt, is not always effective in changing our Microbiome. It can be effective mainly when the Microbiome was damaged, for instance after using antibiotics.
Nowadays, researchers examine how changes to the Microbiome can treat a variety of medical conditions. For example, transferring good bacteria to an area that lacks them (like faecal transplantation from a healthy relative) or creating environmental conditions that allow beneficial bacteria to prosper (using skin creams to set the ideal acidity for specific bacteria). These methods can achieve a beneficial balance in the Microbiome composition, paving the way to a new era in medicine.
The goal: understanding how the Microbiome affects us
Studies show that the Microbiome is most susceptible to changes before adulthood. Later in life, the Microbiome stabilises, except for extreme bodily changes or an ongoing change in diet. Researchers had discovered that changes in the Microbiome during childhood could affect the development of diseases later in life. For example, celiac disease has been connected to certain changes in the gut Microbiome, and the lung Microbiome has been linked to the onset of asthma and allergic reactions. However, the effects of the Microbiome on our health don’t stop after puberty. For instance, scientists have connected the gut Microbiome to the forming of beta-amyloid plaque in the brain – which is considered a leading factor in the development of Alzheimer’s disease.
It was also discovered that certain species of bacteria in the gut Microbiome can affect metabolic illnesses such as diabetes types 1 and 2, morbid obesity and fatty liver. This effect is linked to the bacteria’s ability to change sugar absorption and insulin secretion, as well as the ability to break down sugary foods in the intestine. This discovery has led health firms to offer a new service of personalised diets, based on the Microbiome composition of a patient’s faeces. These personalised diets ensure low sugar intake over time, rather than glucose spikes in the blood that could be dangerous. As the Microbiome community is unique to each person – the recommended diet for each patient is unique as well.
One of the main topics researched today is predicting the effect of certain drugs on our body, based on the Microbiome. Some studies link gut bacteria to the way our body reacts to medicine – even if the drug did no go through the digestive system at all. For example, the existence of a specific gut bacteria was found to predict the effect of anti-cancer immunotherapy medication from a specific group. It is unclear at this stage whether the existence of the bacteria is somehow affecting the mechanism of the drug or whether a third factor affects them both.
The challenges and potential of the Microbiome
Many achievements and discoveries aside, Microbiome research still faces considerable challenges. Many questions on the way bacteria works remain unanswered, such as whether the quality, quantity, or ratio of bacteria affects its functions. Also, some parts of the Microbiome appear “dormant”, despite the presence of their DNA. Thus, more research is needed as to what makes certain bacteria flourish in the Microbiome.
Another challenge for Microbiome-based medicine is personalising treatments and creating custom “Microbiome cocktails” for each patient. It is likely to assume that such personalisation would make these treatments costly, at least at the beginning, so they wouldsuit mainly affluent populations.
Despite the challenges, the research of the human Microbiome shows great potential. By understanding how the Microbiome functions, researchers could not only predict future illness and choose appropriate treatment – but also develop new, advanced medication and treatments. Changing the Microbiome composition and using it to effectively treat for various diseases may cause fewer side effects, compared to treatments available today, and of course prevent needless suffering. The more we know about the human Microbiome and how it works, the more we can offer smarter, more effective medicine in the future.