How Does Diet Affect Your Gut Health?

The gut microbiome, a large ecosystem made up of billions of various microbes and their combined genes, lives in our digestive tract. Our body's microbes are part of a very complex ecological system that is important to many aspects of nutrition and wellness. This includes:

• hundreds of thousands of essential metabolites, enzymes, and vitamins are transformed and created (many of which cannot be produced by humans and are not available directly through diet),
• nutrient extraction from our food,
• and our metabolic responses to food.

Did you know that cardiovascular disease, type 2 diabetes, inflammatory bowel disease, cancer, and obesity have all been linked to the composition and community of the gut microbiome?[1]

Therefore, targeting gut microbiota composition is considered a promising treatment for several diseases.

Your gut microbiome is unique! 

A person's microbiota network is completely unique and is first determined by their DNA. Microorganisms are initially seen by a person when they are an infant, in the birth canal after delivery, and in the mother's breast milk.[2] The specific species of microorganisms to which the newborn is exposed solely depends on the living species in the mother. Later, dietary changes and environmental exposures can alter a person's microbiome, either for the better or worse in terms of health and disease risk.

Research shows that even identical twins have very different gut microbiomes, with unrelated individuals sharing 30% and twins sharing 34% of the same gut microbes at species level.[3]

What the research has to say about diet & gut health

It has been demonstrated that the composition of the diet's nutrients has a significant impact on both the individual members of the microbiota and communities of those microorganisms. For examples, Prevotella thrives on carbohydrates, Bifidobacteria gain benefits from dietary fiber, and Bacteroidetes prefers specific fats to thrive.[3]

Probiotics, polyphenols, carbohydrates (digestible and indigestible), lipids, and proteins, all cause changes in the microbiome, which have an effect on the host's immune and metabolic markers.[1] For instance, consuming animal protein increases the abundance of bile-tolerant organisms like Bacteroides, Alistipes, and Bilophila and decreases the proportion of the Roseburia/E. rectale group, all of which positively correlate with total microbial diversity.[1]

A new study, published in Nature Medicine, found that dietary habits that are less nutritious (such as dairy desserts, fatty meats, and processed foods) promoted gut species that were connected to blood sugar, cholesterol, and inflammatory measurements that are strongly linked to a higher risk of cardiac events, strokes, and type 2 diabetes.[4]

On the other hand, a more diverse gut microbiota was associated with good eating habits (high-fiber foods like spinach and broccoli, almonds, and healthy animal foods like fish and eggs), as well as measurements associated with a reduced risk of developing several chronic diseases.[4]

The study also discovered that polyunsaturated fats, which may be found in fish, walnuts, pumpkin, flax and chia seeds, sunflower, safflower, and un-hydrogenated soybean oils, promote the growth of healthy gut species that are associated with a lower chance of developing chronic diseases.[4]

In other words, the study demonstrated that a healthy gut microbiome may be achieved by consuming more unprocessed plant foods, such as fruits, vegetables, whole grains, nuts, and seeds.[4] Fish and eggs are a couple of good animal product choices. Additionally, it is possible to prevent colonization of the gut with less healthy intestinal species by avoiding specific animal meals like red meat and bacon, dairy products, and highly processed diets (even processed plant foods like sauces, baked beans, juices, or drinks and desserts with added sugar).[4]

Prebiotics, fiber, probiotics, and fermented foods have all been extensively researched within the context of nutrition as means of preserving the gut microbiota's health and resilience.

What are probiotics, prebiotics, and fermented foods?

Probiotics are live microorganisms that are beneficial to health. They are usually present in yogurts and certain fermented foods and dietary supplements. They help your body by engaging with immune cells that line the digestive tract, assisting the gut microbiota in preventing the growth of harmful bacteria, and creating short-chain fatty acids that have both local and systemic health effects.

Prebiotics are a source of food for your gut’s healthy bacteria. They’re carbs your body can’t digest and they travel to your lower digestive tract where they act as food to encourage the growth of good bacteria! Prebiotics can assist in improving bowel patterns, including reducing constipation and diarrhea, and can also help with IBS symptoms.

Learn more about prebiotics and probiotics in this blog post!

Fermented foods are produced when living microorganisms (bacteria, yeasts) alter a food. This new food has a different texture and flavor as a result of the change. However, not all fermented foods are probiotics since not all contain living, well-characterized organisms that are beneficial to health. For example, yogurt is a food that has been fermented and contains probiotics. When lactic acid bacteria changes milk, the resulting yogurt has better nutritional qualities than milk (greater vitamin and mineral content) and is easier to digest. Yogurt improves lactose digestion due to the bacteria it contains (Lactobacillus acidophilus and Streptococcus thermophilus), and its use has also been linked to a healthier lifestyle.

I bet you’ve heard the saying, “You are what you eat” before… Well this common saying is further clarified by science, but maybe we should say “You are what your gut microbes do with what you eat!” instead. 

We hope this blog post helped you understand how complex and unique your gut microbiome is and how big of an impact your diet plays on gut health! 

References: 

1. Singh, R. K., Chang, H.-W., Yan, D., Lee, K. M., Ucmak, D., Wong, K., Abrouk, M., Farahnik, B., Nakamura, M., Zhu, T. H., Bhutani, T., & Liao, W. (2017). Influence of diet on the gut microbiome and implications for human health. Journal of Translational Medicine, 15(1), 73.
2. Ursell, L. K., Metcalf, J. L., Parfrey, L. W., & Knight, R. (2012). Defining the human microbiome. Nutrition Reviews, 70 Suppl 1(Suppl 1), S38-44.
3. Alcock, J., Maley, C. C., & Aktipis, C. A. (2014). Is eating behavior manipulated by the gastrointestinal microbiota? Evolutionary pressures and potential mechanisms: Prospects & Overviews. BioEssays: News and Reviews in Molecular, Cellular and Developmental Biology, 36(10), 940–949.
4. Asnicar, F. (2021, February 27). Microbiome connections with host metabolism and habitual diet from 1,098 deeply phenotyped individuals. Nih.gov.