You (And Your Gut) Are What You Eat

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​Zaria Starfeldt, BA

Diet is a huge contributor to and risk factor for chronic diseases. The calories and nutrient content in food explain much of this relationship, but researchers have discovered bacteria that live in the human gut and could contribute to disease as well. 

The typical Western pattern diet, or Standard American Diet, is characterized by overconsumption of refined grains, added sugar, animal protein, and saturated fat, along with underconsumption of plant-based foods. This type of diet paired with a sedentary lifestyle are recent changes in our evolutionary history, as are the lifestyle diseases believed to stem from this shift. According to the World Health Organization, obesity, type 2 diabetes, cardiovascular disease, and other chronic diseases are common in all populations in higher income countries, with low income individuals bearing a higher burden. But, these diseases are fast rising in nations undergoing rapid urbanization and globalization. While exploring these changes, researchers are studying the trillions of bacteria that live in the human gastrointestinal tract; several may be involved in the body’s response to the Western lifestyle.

A healthy gut microbiome is characterized by diversity of bacteria, and research has shown that the Western pattern diet reduces microbial diversity. Most researchers agree that the refined grains, starch, and added sugars that are characteristic of the Western diet, along with excessive antibiotic use and modern sanitation, inhibit bacterial diversification. Alternatively, a varied diet of fresh fruits and vegetables promotes bacterial diversity. These categories of nutrients and their harmful or beneficial effects on our bodies are in opposition to each other, and in populations burdened by chronic disease, the harmful components dominate.

When the non-digestible carbohydrates that comprise dietary fiber (as commonly found in fruits and vegetables) are fermented in the gut, short chain fatty acids (SCFA) are produced. These SCFA help to regulate microbial activity, maintaining healthy metabolic signaling that when otherwise inhibited, allows for proinflammatory pathways to dominate. These SCFA help in the gut and also beyond; their anti-inflammatory components may protect against metabolic disorders like obesity, type 2 diabetes, and cardiovascular disease, as well as some immune system diseases.

Probiotics and prebiotics also may keep the gut healthy. Probiotics are live, indigestible microorganisms similar to the beneficial bacteria already living in the gut. Prebiotics are compounds that stimulate beneficial bacterial growth. Benefits of probiotics include normalizing the gut microbiome and intestinal function, mitigating pathogens, and increasing SCFA production. It is not yet clear which species or strains are the most beneficial. Research clarifying species- and strain-specific benefits will be the next step forward in probiotic intervention.

While probiotics and prebiotics may emerge as helpful for preventing chronic disease, current evidence points to consuming a variety of plant-based foods as a major first step in promoting gut microbiome health. Gut health is emerging as a critical piece of overall health through its associations with diet quality and metabolic and inflammatory chronic diseases. Understanding the gut microbiome, our ability to influence it, and its ability to change disease trajectories may be crucial in combating chronic Western disease.

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About the author:

​Zaria Starfeldt joined Project Viva as a Research Assistant in September 2018. Prior to Viva, she worked as a Research Assistant in the Center for Human Growth and Development at Michigan Medicine, collecting data with mothers and infants to investigate precursors to childhood obesity. Zaria received her BA in Biopsychology, Cognition and Neuroscience, with a minor in Community Action and Social Change from the University of Michigan in 2017. She hopes to earn an MPH and continue her career in the Public Health field. Outside of work, Zaria enjoys spending time with her friends and family, exploring Boston, and watching Michigan sports.