The human microbiome is a collective term for all the microorganisms, such as bacteria, fungi, and viruses, living in and on the human body. Microbes are the microorganisms that interact in the microbiome. Just like organisms in Earth’s ecosystems, our microbial population changes when our environment changes. The microbes that are the best equipped to live in a particular environment, are the microbes that survive.
Within a few years after birth, we are covered in thousands of different microbes, and they colonize the entire body. Microbe variation is highest during childhood, and gradually decreases with age. Even still, the microbiome continues to change in response to events like illness, disease, antibiotic treatment, fever, stress, injury, and changes in diet.
Of all the human microbial communities, the gastrointestinal (GI) microbiota has the most significant effect on human physiology because of its influence on the development and maintenance of the immune system.
The GI microbiota is a complex ecosystem comprised of tens to hundreds of trillions of microbes that are distributed throughout the gut. Within this structure, the majority of the GI microbiota are bacteria—containing over five million genes that code for the production of specific proteins or enzymes that initiate particular physiologic functions in the host.
Disruptions of GI microbiota are linked with a wide range of health disorders including obesity, hypertension, and diabetes. Alternately, the structure of the microbial communities can positively modulate energy extraction, glucose metabolism, vitamin production, and host immunity.
Our microbes vary with gender, diet, climate, age, occupation, and hygiene. However, long-term diet is believed to be the environmental factor with the most significant impact on the gastrointestinal microbiota.
Manipulating the microbiome to improve health status is becoming increasingly common. For example, metabolic or endocrine disorders may be a potential target for using the GI microbiome to individualize dietary interventions. In GI conditions, such as Irritable Bowel Syndrome, an opportunity may exist to reduce symptoms severity by manipulating the bacteria present in the gut.
Utilization of the microbiome in specific clinical situations also has the potential to improve clinical outcomes in diabetes management, cardiovascular disease, obesity, and potentially nonalcoholic fatty liver disease. Dietary intervention in nonalcoholic fatty liver disease is one area that could particularly benefit from incorporating features of the microbiome into its assessment. Altering the substrates used by the bacteria in the gut may alter the metabolites produced and reduce liver damage.
Dietary fiber has been shown to promote diversity of the microbiome, which gives reason to encourage patients to increase their fiber intake. Furthermore, incorporating a wider range of fiber sources provides a greater range of substrates for the microbiome, giving the opportunity for a wider range of bacteria to become established in the gastrointestinal tract.
Knowledge of the GI microbiome provides an opportunity to promote individualized nutritional advice to enhance overall health and wellbeing. Specifically, it shows promise for those with a metabolic, endocrine, and/or gastrointestinal disorder.
References
Chung, S., Ravel, J., & Regan, M. (2018). Clinical relevance of gastrointestinal microbiota during pregnancy: A primer for nurses. Biological Research for Nursing, 20(1), 84-102. doi:10.1177/1099800417732412
Harvie, B. (2017). Using the Human Gastrointestinal Microbiome to Personalize Nutrition Advice: Are Registered Dietitian Nutritionists Ready for the Opportunities and Challenges? Journal of the Academy of Nutrition and Dietetics, 117(12), 1865-1869.
Your Changing Microbiome. (n.d.). Retrieved January 10, 2018, from http://learn.genetics.utah. edu/content/microbiome/changing/
Written by Nicole Lindel ~ Nutrition Education Master’s Student at Columbia University