The Impact of Diet
The development of DNA sequencing technologies has enabled scientists to measure and analyze the composition of the human microbiome. This has led to a boom in research on the relationship between the composition of our microbiome and our overall health.
One of the key links that has been elucidated by this research is the intricate relationship between our diet and the trillions of bacteria, fungi, and viruses that make up our microbiome. What we eat functions as both a source of microbiota as well as the fuel that powers the different types of bacteria living in our gut.
While much remains to be understood, we now know that long-term changes to our diet can have a lasting effect on the overall composition of our microbiome, potentially leading to better health outcomes.
Recently, scientists from George Washington University and the National Institute of Standards and Technology decided to conduct a literature review of 86 studies on the relationship between diet and the gut microbiome to assess the current state of knowledge.
The Key Findings Thus Far:
Each microbiome is unique: No two individuals share the same microbiome. This has made it difficult to define what constitutes a “healthy” microbiome. Two healthy individuals of similar age and demographic background can have vastly different microbiome profiles. It is true that comparison of the microbiome profiles of sick and healthy people has revealed correlations between many diseases and microbiome composition. However, whether microbiome composition is the cause or an effect of the disease is just starting to be understood and much work remains to be done.
Diet Diversity: While currently there is no consensus in the scientific community on what defines a “healthy” microbiome, it is thought that higher microbial diversity is one of the key indicators, along with the absence of pathogenic (diseased causing) species. The diversity of the bacteria in our microbiome is highly correlated to the diversity in our diet as well as the quality of the food we eat.
Fiber: Diversity is particularly important when it comes to fiber. According to the research review, diversity in the types of plant-food fibers we consume leads to more diverse microbiota.
Carbohydrates: A diet rich in complex carbohydrates (such as those found in beans, whole grains, and vegetables) may facilitate energy harvesting from fibers supporting a bigger diversity of microbiota. This is also correlated with lower incidence of intestinal infections.
Fat & Protein: high fat, high protein diets combined with low fiber intake is correlated to decreases in the diversity of microbiota. Protein metabolism by the microbiota may result in the production of by-products that have been linked to atherosclerosis and colorectal cancer. However, more research is required to understand the elements contributing to these outcomes
Prebiotics: these are a specific type of fiber that has been shown to increase the growth or metabolism of members of the microbiota. Given the broad variation of microbiome compositions, significant variation in the response of individuals to supplementation with prebiotics has been observed. In fact, some research subjects have been non-responsive to prebiotics
Calorie intake: there is no simple linear relationship between the number of calories consumed and the composition and function of the microbiome. Evidence suggests that there is a U-shaped relationship between the two, with too few or too many calories consumed being correlated with less diversity of microbiota.
What you can do
It seems that the strongest predictor of a healthy microbiome is diet diversity, particularly when it comes to fiber-rich plant food. As a rule of thumb, try increasing the diversity of vegetables, nuts, and beans that you consume. Fiber-rich options include: lentils, split peas, chickpeas, avocadoes, almonds, chia seeds, sunflower feeds, pistachios and of course, oats (preferably whole!)
If you are looking to be at the forefront of microbiome health, you can try Viome. This company evaluates your specific microbiome’s diversity and makes personalized food and supplement recommendations. Let us know what you think!