Shilpa Ravella, M.D.


By Shilpa Ravella, M.D.


Shilpa Ravella, M.D. is a gastroenterologist, Assistant Professor of Medicine at Columbia University Medical Center, and the author of the book “A Silent Fire: The Story of Inflammation, Diet & Disease.” You can follow her on Instagram at Shilpa.Ravella and Twitter at Shilparavella.

How Diversifying Probiotic Sources Can Optimize Gut Health

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May 10, 2023

Gut health is intricately tied to the trillions of bacteria, viruses, protozoa, and fungi that live inside our intestines. Together, these germs make up the gut microbiome, a rich ecosystem with a metabolic capacity that exceeds that of the liver1

Today, research on the role of the gut microbiome in human health—and how we can maintain a balance of beneficial germs—continues to accrue. As a gastroenterologist, here are five lesser-discussed facts about gut health I want more people to know:


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Your intestines are a central player in immune health and inflammation

We know today that the gut microbiome plays a crucial role in immune function and inflammation2. Adequate exposure to the right quantity and quality of germs at birth and beyond leads to a balanced immune system, one that defends the body while avoiding overreactions to harmless food, germs, or other matter that may lead to autoimmune diseases. 

An imbalance in the microbiome, or dysbiosis, is tied to all kinds of chronic diseases, including heart disease3, cancer4, obesity5, diabetes6, autoimmune conditions7, and neurodegenerative ailments8. A dysbiotic microbiome is often an inflammatory one, with changes in the variety of microbial species, the chemicals they make, and the genes they stimulate. Inflammation may begin in the gut and weave through the body, contributing to illness.  


At least 95% of Americans are deficient in nature’s most anti-inflammatory nutrient

The most important food for the gut microbiome is fiber from a variety of whole plant foods, including fruits, vegetables, whole grains, legumes, and nuts. Gut microbes digest fiber and produce beneficial metabolites like short-chain fatty acids, which nourish the gut barrier, improve immune function and help to prevent inflammation. 

Unfortunately, at least 95% of Americans fail to meet the daily recommended dietary allowance (RDA) of fiber in the diet (38 grams for men and 25 grams for women). Meanwhile, optimizing gut health means going beyond RDAs. The more fiber you eat, the more you are able to cultivate beneficial, fiber-digesting gut bacteria and improve the overall diversity of species that make up the gut microbiome. A diverse gut microbiome is an important marker of gut health. 

RELATED READ: 8 Fiber Benefits You Didn’t Know About 


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Food diversity is just as critical—or more so—than quantity   

While we need to include a good amount of whole plant foods in our daily diet, we also need to be mindful of the types of plants we are consuming. The most important factors in cultivating a diverse gut microbiome are both the quantity and diversity of whole plant foods. For example, seaweed contains important fibers for gut health that are not present in terrestrial plants. In one 2011 study of middle-aged adults, the diversity of fruits and vegetables9 consumed was a better predictor of lower inflammation in the body than the absolute quantity consumed. And in 2018, research conducted by the American Gut Project revealed that people who eat at least 30 different plants each week have much greater microbial diversity than those who eat only around 10.


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“Ugly” food is good for both your gut and the environment

Each year, around a quarter of produce in the U.S. is thrown away for cosmetic reasons, including strange shapes and curves and minor blemishes, contributing to global food waste and climate change. But these so-called imperfect foods may be even more nutritious and adept at fighting inflammation than their attractive counterparts. 

Plants grown with fewer pesticides, for example, produce higher amounts of beneficial nutrients while battling pests and lower amounts of sugars. These plants, although physically scarred by their struggles, may be especially healthful for our gut.


We should all be eating fermented foods

For the average healthy person, including fermented foods in the daily diet—even a few tablespoons each day is a great start—is helpful for gut health. While fermented foods contain lower bacterial counts than probiotic supplements, they have a greater variety of species, allowing us to consume cooperative families of naturally bred microbes and increasing the chance of running into a helpful microbe. 


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The takeaway

We know that the gut microbiome is involved in a plethora of essential functions in our bodies: Gut microbes ferment foods we cannot digest, extracting energy and producing vitamins, minerals, and other helpful compounds. They degrade toxic substances and defend us against deadly germs. By taking simple steps daily, we can support these microbes that do so much to support us.