Genetic Factors 

It is now known that the human microbiome has a significant impact on health and is related to many disorders. This then begs the question; what determines microbiome composition?

Human Gut Microbiome Review:

The link between host genetics and gut microbiome compositions is an area of ongoing research; and there is still so much to learn. The human gut houses a complex community of microbes, called the gut microbiome. The gut microbiome consists of a dynamic population of bacteria and microbes that differ from one person to another and continually change structure with time. The gut microbiome continually interacts with its host; meaning that changes in microbial communities may affect the individual’s health. Research has indicated a strong link between gut microbiota and gastrointestinal tract function and disease. Gut microbiota have also been found to be involved in metabolism transformations and energy harvest. Many more links have been found between the gut microbiome and organs, tissues and systems beyond the gut itself. For example, the “Gut-Brain Axis”, which involves biochemical signaling between the gastrointestinal tract and the nervous system that is important in healthy brain function.

Link Between Genetics and Microbiome Composition:

The burning question becomes, what decides microbiome composition? Ecological sciences define factors affecting microbiome composition as a combination of environmental factors, including diet and host-defined ones. There is a deep and complex interaction between microbiome and host; both have evolved together, potentially explaining possible microbiome adaptations. There are recent studies that have shown gut microbiota to be similar among family members. However, it is also important to note that individual variations were observed. There have also been several studies looking at both monozygotic (identical) twins and dizygotic (fraternal) twins. One such study found microbes to be more similar for identical twins than fraternal twins. Other studies showed that there were certain bacterial families that seemed to have a stronger link to the genome, as there were greater similarities between identical than fraternal twins. There is also one study that led to the hypothesis that genetics may play a larger role in the composition of an individual gut microbiome during an initial stage of life (1 month), but later (12 months) environmental factors become a larger determinant.

What this Means for the Future:

There is still so much to be learned about the relationship between human genetics and microbiome composition. The research that has been done so far is just a taste of the potential information to come in the next handful of years. More research will result in a better understanding of the relationship between the human body and the microbiota that live within. It is important however, to be aware of the limitations of research that is available to date. Most of the studies available for review right now are small volume studies. With smaller studies (approximately ≤ 100-200 participants). this means that there is less data to analyze, resulting in less significant outcomes. It is also important to note that even in well-controlled studies, bacterial composition can still vary significantly. This is because there are factors, other than genetics, that can shape the microbiome. 

Why is it important:

The relationships between gut microbiome, lifestyle, genetics and certain disorders are still not fully understood, and a lot of continuing research is needed to get a better picture of associations or cause and effect. Is microbial composition causing certain health disorders or do both certain health disorders and a change in microbial composition result from the same genomic factor? It is possible that both types of relationships are possible, but further research is needed to better understand these relationships and the nature of some may also depend on the disorder. Further research could lead to more patient-tailored shaping of microbiome treatment. It is important to think about what can be done in the meantime to better protect oneself and the gut microbiome while waiting for further research. There are certain diet/lifestyle patterns and food choices that have been shown to benefit the human microbiome. This includes: eating a balanced diet rich in whole foods, limiting processed food intake, participating in physical activity and avoiding unhealthy lifestyle habits.

Goals

1. Be Aware:
   • As in previous weeks, being aware is always the first step to making changes. Review this week’s presentation and write-up.
   • Take note of the possible connections between genetics and human microbiome, but remain aware of the potential environmental effects on the microbiome.
2. Take Note:
   • .Continue your food journal from previous weeks. Complete for at least 4 days, but is best if you can complete for an entire week.
   • Make sure to include any GI symptoms that may come up throughout the day.
   • Also note your intake of whole foods, probiotic rich foods and processed foods.
3. Take Action:
   • .Alter: If you notice a lack of whole or probiotic rich food intake, find ways to include more of these foods in your diet. If you are consuming a lot of processed foods and sugar, try going at least one day without them.
   • Consult: If you are having trouble identifying patterns, including or eliminating certain foods, picking out culprits of GI distress or just want more guidance in your diet patterns, consult a registered dietitian.