Unlocking the Secrets of the Microbiome
What is the microbiome?
Our microbiome is the collection of microorganisms that reside within and on our bodies. Surprisingly, our bodies have ten times more microbial cells than our own cells! Most of these bacteria benefit us, they are commensal so the food we consume plays a crucial role in maintaining their health. While humans possess 23,000 genes, our microbial counterparts contribute over 3 million genes to our overall genetic makeup.
Let's define some terms.
Microbiota: microorganisms that live in the environment
Microbiome: combined genetic material of microorganisms in a niche
Dysbiosis: derangement in microbiota
Metabalome: functions properties of the gut microbiota
The gut is home to as many as 100 trillion symbiotic microbes. Dysbiosis of microbe species likely contributes to fat gain and body composition imbalance. Our microbiome produces physiologically active substances that affect our immune and metabolic functions. A healthy microbiome is characterized by a variety of species and aids in the metabolism of nutrients and medications while also playing a crucial role in protecting our gut barrier against harmful pathogens.
What factors influence our microbiome?
Various factors can impact our microbiome, such as how we were born, our genetic makeup, whether we were breastfed or not, and whether we have pets or a garden. To improve our microbiome, we can engage in activities like regular exercise, consuming whole foods rich in fiber, and ensuring we get sufficient sleep. Although many unresolved clinical questions surround the perfect microbiome and potentially harmful bacteria, one fact remains clear: a diverse range of microbes is crucial for maintaining a healthy body, gut, and mind.
Conditions associated with microbiome dysbiosis
A variety of conditions, including high blood pressure, multiple sclerosis, and depression, are associated with microbiome dysbiosis. Importantly, adipose tissue dysfunction and obesity are strongly linked to an abnormal or unhealthy microbiome.
What is a healthy microbiome?
Now, this is where it gets tricky. There is no strong scientific data on what is the best or most healthy microbiome; however, it is clear that a diverse range of microbial species, with two main phyla - bacteroidetes and fermicuties - is necessary for optimal gut health. Unfortunately, taking probiotic pills is unlikely to improve your gut health since they often contain only a few dead microbes. There likely is a benefit from fermented foods such as kombucha, kimchi, and vinegar with the mother, which contain living polycultures of a variety of microbes.
Effects on energy metabolism
Our metabolome has massive effects on our energy metabolism. Our microbiota can increase the calories extracted from our food, meaning two people with different microbiomes can eat the same meal and have a different net intake of calories from the same food. This fact is critical in dispelling the "calories in, calories out" gross oversimplification, but that will be addressed further in another post. The metabolome affects our body's metabolism of cholesterol. An unhealthy microbiome has been shown to cause inflammation. This is in part due to an unhealthy microbiome eating our intestinal lining, causing a leaky gut. Our microbes also affect our hormone pathways. Our microbes can change the secretion of ghrelin (hunger hormone) and GLP-1 (one of our seven satiety hormones). The gut microbiome not only affects calorie absorption from meals but also induces more fat formation by changing our gene expression. In experiments with mice, when mice without any germs were transplanted with the microbes of mice with obesity, they too developed obesity and critical insulin resistance.
All the other ways our microbes change
Our brains and gut are intricately linked, and much of our eating behavior is influenced by signals from our brains that we are unaware of. Interestingly, our gut microbiome affects the types of signals our brain sends out. The microbiome can, for example, impact the amount of serotonin (the "happy hormone") that our gut produces, which can make us crave more junk foods or less healthy foods. Additionally, we rely on our gut microbes to digest parts of our food that we cannot digest on our own, such as complex carbohydrates that are broken down into short-chain fatty acids that we can absorb. An unhealthy diet, which is rich in ultra-processed foods (UPFs), can deplete our healthy gut microbes and shift the balance in favor of less beneficial ones. These less helpful microbes can then influence our behavior to seek out more UPFs, creating a vicious cycle. Thus, by consuming a diet that lacks nutritional value, we harm not only ourselves but also our gut microbiome.
Conclusion
In conclusion, the microbiome is an essential aspect of our health that influences various body functions, including energy metabolism, hormone secretion, and immunity. A healthy microbiome modulates our glycemic response, cardiovascular risk, and inflammation. A healthy microbiome is characterized by diversity and balance of microbial species. While there is still a lot to learn about the microbiome, it is clear that maintaining a healthy microbiome is crucial for overall health. By eating whole foods, exercising, getting enough sleep, and avoiding UPFs, we can help ensure that our microbiome stays healthy, which, in turn, helps us stay healthy.