Blog 3: The Microbiome

The human microbiome is a complex and diverse community of microorganisms that offers great contributions to human health and disease, whether that be positive or negative. As soon as a baby passes through their mother’s birth canal, they gain vitally important microbes that will help establish the state of their microbiome, which will persist throughout adulthood. In fact, researchers suggest that by the time a child is three years old, their microbiome largely resembles that of an adult, indicating that the first few years of a child’s life are incredibly important in determining their life-long microbial community. However, it is still believed that the microbiome can be changed in adulthood through certain diet practices, or other environmental factors. Establishing a diverse and well-adapted microbiome is important because an imbalance in the microbiota might be linked to certain health issues. Two articles that discuss either how an imbalance in the gut microbiota is related to an increased risk of certain health issues and how this known imbalance might be used to treat disease will be discussed below.

In a literature review titled “Maternal Microbiome and Metabolic Health Program Microbiome Development and Health of the Offspring,” authors Marta Calatayud, Omry Koren, and Maria Carmen Collado discuss how an infant’s microbiome can be altered through different prenatal and postnatal practices and offers an interesting insight into the many different factors of microbial development. According to the authors, an infant’s predisposition for developing diabetes, obesity, and allergies might be influenced before the baby even passes through the birth canal. These increased risks can be associated with certain prenatal practices, such as diet, stress, or chemical products considered foreign to the body, otherwise known as xenobiotics. For example, through multiple studies it was determined that infants are at a higher risk of developing obesity or other metabolic syndromes if the mother is obese or consumes a high-fat diet during pregnancy, indicating that maternal practices can have an influence on her child’s microbiome. However, the authors conclude that while prenatal practices do impact neonatal microbiome development, postnatal practices, such as how the baby was delivered, whether it was breastfed or not, and other environmental influences, have a larger impact on the microbial community of the child. Although, they both make significant contributions to the child’s future microbiome and predisposition to certain diseases or disorders. 

Researchers have also noticed possible links between autoimmune disorders and an imbalance in gut microflora. However, this does not necessarily imply causation, as researchers have yet to establish a singular, universal idea of what a healthy microbiome looks like. For example, people that live in the US have vastly different microbiomes compared to people in other regions of the world, especially less industrialized regions. One possible reason for this difference in microbial communities is the change in diet more industrialized regions experience. As an illustration, researchers noticed that the westernized diet featured a significant lack of fiber, an important nutrient associated with digestive health. As a result, the microbial community of a U.S. resident usually shows a decreased amount of the bacteria genera Prevotella, a bacteria known to help digest fiber, showing that environmental factors can have a significant impact on one’s microbial community. However, even though causation can not yet be established, knowing that this linkage exists can help researchers develop possible treatments for autoimmune diseases. According to a literature review titled “Immunomodulatory and anti-inflammatory effects of probiotics in multiple sclerosis: asystematic review,” probiotics containing bacteria that are present at reduced levels in individuals with multiple sclerosis might offer a treatment option for forms of multiple sclerosis that are difficult to treat. In multiple studies performed on mice inoculated with an animal model of multiple sclerosis, they found that the mice treated with probiotics had less severe symptoms and a significant delay in the onset of the symptoms than the mice that received no treatment, indicating that the human microbiome plays a dramatic role in the health of an individual and can be manipulated to offer treatment for chronic, autoimmune diseases. Looking to the future of probiotic use for treatment of autoimmune disorders, researchers will need to perform more analyses on a wider variety of microbiomes to establish if missing bacteria are due to a potential autoimmune disorder or if this difference is attributed to environmental factors alone.