The homework assignment #1

Based on what you already know about the human gut microbiota, what do you think are the most important factors influencing a person’s gut microbes? These factors can be anything from lifestyle factors to health status. List three factors and explain (in three sentences or fewer for each) why you think each might affect gut microbes.

The human body is like an ecosystem with many distinct habitats for microbes.  The mouth, nose, lungs, skin, vagina, and gut all have unique microbiota, with the gut being  the center of most of the microbial activity in the body and thus the research.  Three very early factors influence the gut microbiota of an individual over time.

First, in a newborn baby the microbiota are less distinct. As she grows her microbial communities begin to develop, the results depending on whether her birth was vaginal or c-section.  Obviously, from the beginning of time, the most common source of  human microbiota in a newborn was the birth canal of our mothers.  With surgical intervention the theory is that a child is exposed to the mother’s skin microbes instead of vaginal microbes, the genus lactobacillus, important for human health. C-section babies appear to have more diseases like asthma and allergies.

Second, after about 2.5 years, the baby’s gut microbial community should be like a healthy adult, but it has already been influenced by microbes on the parents’ skin, breast milk from her mother or formula from a cow or plant based, and choice of solid foods some of which may be processed.

Third, the child’s microbiota develop within a particular culture--perhaps Finland or Haiti--which includes both home environment and medical care. The home may expose her to animals, siblings, dust and dirt, exposure to rural or city air quality, travel, day care and the neighbor’s kids who will do their share of exchanging microbes.  If the child grows up in the U.S. or other developed nations she will receive  medical care which may include vaccines, antibiotics and nutritional supplements depending on the culture.  This can either assist or disrupt a healthy microbiota.