Comparing Animal-Based vs Plant-Based Diets: Which One has a More Positive Impact on the Microbiome


The majority of the American population (68%) report eating meat in their diet and only 2% report eating a fully plant-based diet. That trend is starting to shift with only 59% of Americans under 30 years old who say they eat meat. The number 1 reason people decide to go plant-based is for their health. In this article, we delve into the research to see if people who have a plant-based diet have healthier gut health and overall health than those who eat meat. 

Our gut microbiome can be influenced by our diet

The live ecosystem of bacteria living in our large intestine is known as our gut microbiome. The main function of our gut microbiome is to help break down foods that we can’t digest, like fiber. Growing research in the field is now showing that the tiny microbes in our gut can have a much broader role in whole-body health and may influence things like our sleep cycles, skin health, stress levels, mood regulation, immune system, and more. Knowing how important this living ecosystem can be for our overall health, we’d want it to be the healthiest it can be.  

Our gut microbiome is always changing and is influenced by many factors such as our age, genetics, medications or supplements that we are taking, and our diet. Research is showing that we actually can improve the health of our gut microbiome, but how? Keep reading to discover healthier diets for a healthier gut microbiome and some quick tips to improve your gut health.

A meat-heavy diet and plant-based diet show differences in the types of gut bacteria they promote

meat-heavy diet consists of a high intake of animal protein, saturated fat, salt, and sugar associated with processed meats like sausage and bacon. A plant-based diet consists of plant protein, fiber, and antioxidants and minimizes all animal products like meat, eggs, and dairy. A vegan diet will eliminate all meat, eggs, dairy, and animal-derived proteins. Studies are showing specific differences in the gut microbiome between meat-heavy and plant-based diets like:

  • Diversity of the gut bacteria 

  • Promotion of the protective gut mucin layer 

  • Differences in types of healthy & unhealthy gut bacteria promoted 

  • Production of anti-inflammatory molecules called short-chain fatty acids (SCFA)

    Diversity of the gut bacteria

    The gut microbiome needs to be diverse with lots of different bacteria types and strains. It also must have a balance between all of the strains of bacteria so that one does not overpower the others, which has been associated with inflammation and disease states. Research has shown that in meat-heavy diets, there is a decrease in bacterial diversity, whereas plant-based diets high in fiber, have more diverse gut bacteria that are also more stable and balanced. This shift to a more diverse gut microbiome seen in plant-based diets is likely because of the amount of fiber eaten that we can’t digest, but our tiny microbes can.

    Promotion of the protective gut mucin layer 

    Along the cells that line our gut, there is a mucin layer that protects against viruses or other pathogens from getting into our body and causing us to get sick or contribute to a “leaky gut.” It is important that this mucin layer is thick to provide the most protection. Diets that are high in meat have an inflammatory action on the mucin layer and overall protective barrier of the gut whereas diets that are plant-based actually help to produce mucin and promote that healthy and protective barrier.

    Differences in the types of bacteria promoted

    As well as having an overall decrease in the number of bacterial strains, meat-heavy diets have been shown to decrease the number of normal and healthy bacteria that live in our gut, which is associated with inflammation and disease. This is likely due to a lack of fruits and vegetables in a meat-heavy diet. Plant-based diets are high in antioxidants because of all the fruits and vegetables, and research has found that the antioxidants from plant-based foods increase bacteria that have anti-inflammatory effects, help fight against pathogens, and are heart-healthy. This is again showing the gut microbiome can have a positive or negative effect on overall health just based on what you eat.

    Production of short-chain fatty acids (SCFA)

    Short-chain fatty acids are molecules that are created by healthy bacteria in the gut when they break down and eat fiber. These molecules are thought to affect gut health and travel around the body and have a health-promoting and an anti-inflammatory effect outside of the gut. Eating a fiber-full plant-based diet has been associated with high levels of certain bacteria that are known to produce short-chain fatty acids. Meat-heavy diets that lack fiber from fruits and vegetables do not produce these anti-inflammatory molecules. 

    You can contribute to the health of your gut by what you eat 

    While completely switching from a meat-heavy diet to a plant-based diet may be challenging to some, there is research showing it can be helpful for weight, energy, and metabolism, reducing inflammation in the body, and preventing obesity and type 2 diabetes. Although switching from a meat-heavy diet to a more plant-based diet may require an adjustment period from your gut to get used to the new foods, a study found that the composition of your microbiome shows changes within 24 hours of switching to a high-fiber diet. Just by incorporating more fruits, vegetables, beans, nuts, seeds, and grains you can contribute to the health of your gut and whole body. 

    Quick tips for eating more plant-based foods 

    •  Incorporate more plant proteins like tempeh, chickpeas, quinoa, and hummus

    • Try out plant-based milk/ yogurt alternatives like almond, coconut, oat, or pea

    • Eat the rainbow-snack on colorful fruits and vegetables throughout the day For all-day fullness, make sure each meal has healthy fat, fiber, and plant protein 

      Dr. Raja Sivamani, MD


      Dr. Raja Sivamani is a board-certified dermatologist and practices as an integrative dermatologist at Pacific Skin Institute. He is an Adjunct Associate Professor of Clinical Dermatology at the University of California, Davis and Director of Clinical Research and the Clinical Trials Unit. He is also an Adjunct Assistant Professor in the Department of Biological Sciences at the California State University, Sacramento and an Associate Professor of Dermatology at California Northstate University, College of Medicine. He engages in clinical practice as well as both clinical and translational research that integrates bioengineering, nutrition, cosmetics, and skin biology. With training in both Allopathic and Ayurvedic medicine, he takes an integrative approach to his patients and in his research. He has published over 100 peer-reviewed research manuscripts, 10 textbook chapters, and a textbook entitled Cosmeceuticals and Active Cosmetics, 3rd Edition with a passion for expanding the evidence and boundaries of integrative medicine for skin care.

      Collective members are paid sponsors and receive compensation for their content, but all opinions are their own.

    • But the point is: Coming to a 100% Vegan-Diet will not lead to the possibilty of “maximum health”. So my sentence is: Become a 6/7 Vegan and a 1/7 Carnivore and everything 100% Organic AND Eat in Accordance to Your Diseases, with Ayurvedic Wisdom. Then You will overcome Your Diseases. That is the way of becoming healthy and then You can become even more healthier. Klaus M. Wissemeier Ayurveda-Ernährungsberater BYVG

      Klaus Wissemeier
    • I love recipes that include lots of different veggies (colors). Thank you for the quick tips!

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