Every surface of our body, from the lungs to the bladder, has a unique makeup of microorganisms. The vast microbial diversity is primarily found in the digestive tract, which is crucial to good gut health, but also conditions that may not appear to be connected to your gut, including cardiovascular health, skin problems, and neurological diseases, among others. While what we know so far on the link between gut microbiota and other organs comes from studying gut bacteria, but others like fungi, yeast, viruses, and parasites are also joining the party.
One of the most studied areas is the connection between the gut and the brain. Microbes in your gut are constantly talking with your brain, contributing to stress and our emotions, but the converse is also possible. In addition to microbes, the gut-brain connection involves the vagus nerve, hormones, immune cells, and metabolites, all of which work as a team to allow the two-way street between the gut and brain.
The implications of these findings suggest that the microbiome may play a role in the development of dementia, autism, and other disorders. However, we still do not know whether an altered microbiome is the cause of brain disorders or merely a consequence.
Gut microbes might also be a hidden cause of difficult-to-control lung diseases. It turns out that the gut microbiota is connected to the lung microbiota, the latter being primarily shaped by the oropharynx microbiome, which varies among individuals but remains stable over time. Scientists are exploring how to leverage commensal microbes in the lung to predict asthmatic flares and improve response to current drugs for lung diseases. Some studies have also suggested that a plant-based diet is essential for keeping inflammation at bay and providing the necessary nutrients to support the immune system and gut microbiome, which are relevant to respiratory health.
The gut is an entrance door to our body, and gut microbiota helps the immune system create a barrier against pathogens. Up to 80% of the immune cells are located in the gut. Seeking a cure for irritable bowel syndrome, researchers have turned to the increased activation of immune defenses in the small intestine. These findings support that gastro-intestinal problems are not in patients’ heads.
The high fermentation of carbohydrates in the large intestine is not the only culprit of symptoms, as scientists theorize that an abdominal infection can temporarily alter the gut barrier. With the barrier disturbed, some food components can get absorbed and trigger localized allergic reactions. However, it is too early to recommend IgG-based elimination diets for patients with IBS who use exclusion diets for symptom management.
Close to the gut, the liver plays a crucial role in the metabolism of food. In healthy individuals, the liver acts as a gatekeeper, removing toxic compounds before they enter the bloodstream. When the gut barrier is disturbed, microorganisms and their metabolites can enter the liver. Scientists are exploring new ways to modulate the gut and liver to mitigate the complications of liver diseases.
The skin is one of the most extensive surfaces of the body and is also connected to what happens in our gut. But unlike the gut microbiome, the skin microbiome is more independent. The connection between the gut and the skin was initially introduced in 2016. Recent studies have shown that an imbalanced gut microbiome can weaken the intestinal wall, a condition already linked to eczema, psoriasis, vitiligo, and acne.
Last, but not least, the study of heart health through the lens of gut microbes can help understand why not everyone’s metabolism responds the same way to diet. Scientists and physicians are beginning to recognize elevated blood levels of trimethylamine N-oxide (TMAO)- a compound derived from diet (e.g., choline, carnitine) and the microbiome- as a marker that can be used to identify patients at higher risk of heart disease. Scientists are seeking new targeted treatments that inhibit the conversion of dietary compounds to TMAO by modulating the gut microbiome and utilizing individual gut microbiome profiles to personalize dietary advice.
Learn more in this video about how the gut microbiome is connected to organs outside the gut and why this matters for improving health:
