The human microbiome is composed of bacteria, viruses and numerous other microbes that reside in and on our bodies. "These microbes have tremendous potential to impact our physiology, both in health and in disease. They contribute metabolic functions, protect against pathogens, educate the immune system, and, through these basic functions, affect directly or indirectly most of our physiologic functions." (Source: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4290017/)
Since this community of micro-organisms, consisting of trillions of microorganisms (also called microbiota) live within and on us communally, they play a significant role in our health and well-being. Each person has a unique network of microbiota that is originally determined by one’s DNA. This reinforces the concept that one person's food or medicine may be another person's poison.
Microbiota stimulate the immune system, break down potentially toxic food compounds, and synthesize certain vitamins and amino acids, the building blocks of proteins.
From a nutritional standpoint, "sugars like table sugar and lactose (milk sugar) are quickly absorbed in the upper part of the small intestine, but more complex carbohydrates like starches and fibers are not as easily digested and may travel lower to the large intestine. There, the microbiota help to break down these compounds with their digestive enzymes. The fermentation of indigestible fibers causes the production of short chain fatty acids (SCFA) that can be used by the body as a nutrient source but also play an important role in muscle function and possibly the prevention of chronic diseases.... The microbiota of a healthy person will also provide protection from pathogenic organisms that enter the body such as through drinking or eating contaminated water or food." (Source: https://www.hsph.harvard.edu/nutritionsource/microbiome/)
What may affect the gut microbiome to help ensure that the network is adequate, functional, and healthy? Consider pre-biotics, probiotics, and diet. Prebiotics are the nutrients that support and help sustain the microbiota. Prebiotics feed our beneficial microbiota. Examples include garlic, onions, leeks, asparagus, dandelion greens, fruits, vegetables, beans, and whole grains. During times of stress, probiotics may be particularly helpful.
Regarding nutrition, "in addition to family genes, environment, and medication use, diet plays a large role in determining what kinds of microbiota live in the colon.... A high-fiber diet in particular affects the type and amount of microbiota in the intestines. Dietary fiber can only be broken down and fermented by enzymes from microbiota living in the colon. Short chain fatty acids (SCFA) are released as a result of fermentation. This lowers the pH of the colon, which in turn determines the type of microbiota present that would survive in this acidic environment. The lower pH limits the growth of some harmful bacteria." (Source: https://www.hsph.harvard.edu/nutritionsource/microbiome/)
The gut microbiome: be mindful of the company you keep. Care and intention may improve your life!