The human body contains approximately 10 trillion human cells, but it is also home to numerous microorganisms. These microorganisms are clusters of bacteria found in various locations, including the skin's surface and deeper layers, as well as in the mouth, nose, lungs, and stomach. The largest population of these bacteria, around 100 trillion and weighing up to 2 kg, exists in the gut. Although this may seem alarming, these bacteria play a vital and beneficial role in maintaining our health.

Ilya Mechinikov was the first scientist to recognize the significance of gut microbes, earning the Nobel Prize in 1908 for his research on the immune system. Residing in Paris during the late 19th century, he witnessed the cholera epidemic affecting many across Europe. Driven by curiosity, Mechinikov began investigating the disease, which led him to consume food contaminated with cholera bacteria. Surprisingly, he remained healthy. Encouraged, he had a colleague partake in the experiment, who also experienced no illness. However, when another colleague was tested, he suffered severe consequences and nearly lost his life. Mechinikov's work ultimately highlighted the complex relationship between gut microbes and health.

What caused the varying reactions to the same illness? By examining cholera microscopically, Mechinikov discovered that certain gut bacteria promoted cholera's growth, while others inhibited it. His research led him to understand that gut bacteria are crucial for human well-being, with the proper microbial balance playing a role in disease prevention. Unfortunately, his insights were not widely recognized during his lifetime and faded into obscurity after his passing in 1916.

Ten years later, the discovery of antibiotics transformed medicine. These powerful medications have saved innumerable lives by enabling healthcare providers to eradicate harmful bacteria that infect injuries, cause severe illnesses, and contaminate food supplies. However, over time, the remarkable effectiveness of antibiotics has led some physicians to prescribe them excessively. Additionally, society has increasingly viewed all germs as harmful, prompting individuals to strive for complete cleanliness. This ongoing battle against microbes has persisted for nearly a century, but this mindset has inadvertently harmed public health, contributing to an increase in allergies and weakened immune systems.

Scientists are increasingly recognizing the crucial connection between microbes and human health. Recent research highlights that the vast array of microbial species in the gut serves various essential roles, making our well-being highly reliant on these diverse organisms. By colonizing our bodies, these microbes inhibit the growth of harmful bacteria. As a result, individuals with a robust bacterial community may experience fewer negative effects from mildly contaminated food, while those with an imbalanced or reduced microbial population could be more susceptible to foodborne illnesses. Additionally, these microbes support our immune system by helping to differentiate between beneficial substances and harmful ones. Consequently, a lack of essential microbes or a decrease in their diversity can lead to several health issues.

Certain microbes assist in digesting vegetables and milk in the stomach. Their absence complicates the absorption of these foods, leading to an imbalanced diet and health issues. Additionally, some bacteria contribute to the production of vitamins B and K, along with essential amino acids for the body.

Certain gut microbes influence the toxicity of specific medications to the liver and affect the efficacy of drugs for heart conditions. Additionally, these microbes play a role in regulating appetite hormones that signal fullness or hunger. A loss of these microbes may lead to increased body fat. A recent study demonstrated that transferring gut bacteria from a lean mouse to an overweight mouse resulted in weight loss for the latter, while the opposite transfer caused the lean mouse to gain weight.

Some researchers recognize the vital importance of microbes and are exploring ways to use this understanding for healing. Instead of relying on antibiotics, they have discovered that restoring or boosting essential microbes lacking in a patient can help treat certain illnesses. For instance, individuals suffering from severe diarrhea, experiencing up to 20 bathroom visits daily, found no relief through antibiotics. Researchers introduced beneficial microbes from a healthy donor into these patients' intestines. Remarkably, just one day after the transplant, all symptoms disappeared, and the diarrhea stopped. These patients returned to a state of health, with their gut microbiota starting to mimic that of the donor, showcasing the potential of microbial therapies in medicine.

Nutritionists recommend several strategies for maintaining a healthy gut, primarily through our diet. Consuming foods rich in beneficial bacteria, such as yogurt, kimchi, and natto, along with a nutrient-dense diet filled with garlic, onions, and unprocessed, fiber-rich grains, helps promote beneficial microbes. It's also crucial to safeguard the existing bacteria in our bodies by steering clear of processed foods. Items like frozen meals, packaged snacks, and canned goods not only lack the necessary beneficial bacteria but also contain harmful chemicals that can damage our gut's good microbes. By making mindful food choices, we can support our gut health effectively while nurturing the microbes that play a vital role in our overall well-being.

One effective way to boost beneficial microbes is by spending more time outdoors. Environments rich in biodiversity, such as forests, beaches, parks, and even small farms or gardens, teem with various bacteria absent in sterile urban settings. Additionally, it's essential to use antibiotics judiciously and reduce their frequency. While antibiotics are vital for maintaining our health by removing harmful germs, they indiscriminately affect both good and bad bacteria. Consequently, any use of antibiotics can inadvertently harm beneficial bacteria alongside the dangerous ones we aim to eliminate.

If we can influence microbes and they, in turn, influence our bodies, it's unwise to view them as separate entities. We should consider the microbes in our intestines as integral to our bodies, akin to blood cells and neurons. It's essential to care for these microbes with the same attention we give to our skin and teeth. Recognizing the interconnectedness of microbes and ourselves can lead to better health and well-being.