This week I am attending Obesity Week in Nashville Tenessee, the joint annual conference of the Obesity Society and the American Society for Metabolic and Bariatric Surgery. It is also a venue where the latest scientific findings are shared before formal publication.
One series of talks focused on the role of gut bacteria and how alterations in the microbiome may impact health. It is a nascent space, and I would say we are barely touching the permafrost on the tip of the iceberg of what will emerge in this space in the coming decades. For starters, we are outnumbered about 9 to 1 in our human cells by our friendly gut bacteria which plays a huge role in our overall health. Most of the research has been focused on mice models as their environments and feeding habits can be easily manipulated to examine different dietary patterns. Benoit Chassaing, a microbiologist at the Institute for Biomedical Sciences at Georgia State University, presented work based on a study published in the British Medical Journal Gut in 2017. Inflammation in the body has long been thought to precede the development of chronic conditions like diabetes. If we look at the inflammatory diseases that have plagued humans in the last 50 years we see a marked increase in Chrons disease, ulcerative colitis, and other gastrointestinal illness; interestingly they are far more prevalent in developed countries who have often experienced dramatic changes in their farming and food environments. Understanding how this shift impacts health will be important if new methods to prevent and treat chronic illness are to emerge.
What Impacts Gut Health – Emulsifiers
Since the human microbiome is challenging given how complex modern living is, studying mice is an excellent proxy to understand how the food we eat impacts our gut microbiota and by association our health. Emulsifiers are often used in processed food to stabilize an oil and water mix, think about store-bought peanut butter you may have at home- have you noticed in some instances the oil is at the top of the jar when you open it? upon stirring the mixture resembles peanut butter and you can spread it on your toast! This is because most commercial peanut butter will have an emulsifier added to stabilize the consistency of the mix. Some controversy exists about this as a food additive.
Chassaing’s study would suggest when mice are fed dietary emulsifiers like polysorbate 80 (P80) or carboxymethylcellulose (CMC) they negatively impact and alter the genetic composition of the gut microbiota. This study also showed a tendency toward promoting inflammation although the authors reflect that inflammation in itself can change the microbiota so its difficult to discern the mice’s natural tendency toward inflammation over the mechanisms induced by the dietary emulsifiers they were being fed as part of the study. While this may seem murky, given the Standard American Diet (SAD) skews toward reliance on processed food and many food types have emulsifiers as food additives understanding their impact on human health will be an important line of research in the future. One exciting finding showed when CMC and P80 treated mice microbiota samples were transplanted into germ-free mice they experienced low-grade inflammation which suggests one potential pathway for metabolic disease.
Do we fully understand dietary patterns that truly impact the health of the microbiome? We know from research that antibiotics also can significantly change the health, diversity, and equilibrium of the microbiome and some early data suggested more persistent alterations in that equilibrium can occur in infancy if children are exposed to repeated doses of antibiotics, which is not uncommon in the first two years of life.
The gut microbiota is a very complex ecosystem that we are just beginning to understand, if as the saying goes “you are what you eat” does that also include the millions of bacteria that aid our digestion?- It would also seem that a whole food dietary pattern with limited processed food might be prudent to blunt the negative impact processed foods appear to have on the microbiome. This field of research is evolving rapidly – we may see a shift from s*it happens to s*it matters!
Thanks for reading – Trina
(Opinions are my own)
Dietary emulsifiers directly alter human microbiota composition and gene expression ex vivo potentiating intestinal inflammation