Healthy gut microbiome: Fruit, veg may provide bacterial diversity

  • The gut microbiome plays an important role in the body’s overall health.
  • A healthy gut microbiome has a diverse range of microorganisms.
  • A new study from Graz University of Technology says eating fruits and vegetables helps provide some of this bacterial diversity in the human gut.

Over the past few years, people have become very aware of their gut microbiome and the importance of keeping it healthy.

A healthy gut microbiome has a diverse range of bacteria, viruses, fungi, and other microorganisms that not only help the digestive system break down food but also support the immune system and the gut-brain axis.

Sometimes, people may be confused about what they need to eat to have a diverse and healthy gut microbiome.

A new study from Graz University of Technology in Austria suggests that it’s as simple as eating more fruits and vegetables.

The findings were published in the journal Gut Microbes.

Conducting the study

For this study, researchers first created a catalog of microbiome data from fruits and vegetables. This allowed them to figure out which bacteria and other plant microorganisms come from each type of produce.

Next, scientists compared their data catalog with publicly available data from two studies on intestinal flora — the TEDDY project looking at the development of babies in a long-term study and the American Gut Project examining the intestinal microbiome of adults.

With so much data in their hands, the researchers were able to find evidence of fruit and vegetable microflora in the gut.

Influencing how fruits and vegetables are grown

Dr. Gabriele Berg, head of the Institute of Environmental Biotechnology at Graz University of Technology in Austria and lead author of this study, told Medical News Today these findings may affect how fresh fruits and vegetables are grown and/or packaged in the future because intense agri- and horticulture is a strong driver of the environmental microbiome that influences human health, as well as planetary health.

“In my eyes, we have to rethink a lot of our current agricultural practices. For example, breeding for yield and resistance only, seed production and control, use of fertilizers and pesticides, food storage, and processing,” she said.

Dr. Berg is already working on a new study where people on three continents eat the same things for a certain period. This will allow researchers to examine how where foods are grown may affect the gut microbiome.

“Fresh fruit and vegetables will always have the best microbiome; agriculture or processing companies already have a major influence here. And the storage and processing of food must also be critically reconsidered,” Dr. Berg added.

Importance of eating produce during infancy

From their findings, the scientists found that eating more fruits and vegetables during infancy has a positive influence on the development of the immune system during the first three years of life.

According to Dr. Babak Firoozi, a board certified gastroenterologist at MemorialCare Orange Coast Medical Center in Fountain Valley, CA, who was not involved in this study, during infancy, the gut flora is heavily influenced by the mother, as well as by the early introduction of fruits and vegetables.

“The overall gut microbiota appears to settle and not change significantly after the baby turns 2,” he told MNT. “Therefore, it is crucial that parents introduce healthy eating at an early age, so their child can have a lifelong gut microbiota that is diverse and [for] promoting of overall good health.”

Monique Richard, a registered dietitian nutritionist, owner of Nutrition-In-Sight, and national media spokesperson for the Academy of Nutrition Dietetics, who was not involved in this study, agreed: “Exposure is key for the introduction and establishment of lifelong habits to include a variety of fruits and vegetables, especially for microbiome colonization between ages 1 to 3.”

“Modeling balance and consumption of a wide variety of diverse foods and food groups by parents/guardians is essential, as well as having those foods available and prepared on a regular basis for the child to consume at meal and snack time,” she added.

Bacterial diversity is key for a healthy gut

The human gut microbiome consists of trillions of microorganisms, such as bacteria and viruses.

No two microbiomes are the same. Researchers estimate the gut microbiomes of individual humans are 80-90% different when compared to each other.

What everyone’s microbiomes have in common is the need for them to be healthy. A healthy gut microbiome is both rich in the total amount of microorganisms it contains and diverse in the types of those microorganisms. This allows the microbiome to function better as it can fulfill more functions.

However, microbiota do not stay in the microbiome forever. And some things may make their numbers decrease, such as aging, environmental factors, or taking certain medications like antibiotics.

For this reason, people have to actively work to keep their gut microbiome varied and healthy. Some ways to do that include:

  • eat a wide range of foods, including prebiotic and fermented foods
  • exercise
  • lower stress
  • avoid artificial sweeteners
  • take probiotics as necessary

Lack of diversity or a low amount of vital microorganisms in the gut can lead to a variety of health issues, including autoimmune diseases, digestive disorders, high cholesterol, and obesity.

Why does eating veggies and fruit help the gut?

Richard said one of the many reasons fruits and vegetables are so important for gut health is related to their fiber — both insoluble and soluble — content.

“[Fiber] adds bulk to our stool, which helps move waste through our intestines to be excreted,” she explained to MNT.

“Soluble fiber dissolves with water but also attracts water, allowing it the capacity to bind together, grabbing fat and cholesterol and is able to help ‘sweep’ and ‘clear’ out our intestinal tract. These fibers, along with the multitude of nutrients found in fruits and vegetables, literally feed the microbiome in our gut, activate, protect, and support our bodily functions physiologically and biologically.”
— Monique Richard

Eating fruits and vegetables that contribute to the diversity of your gut microbiome helps with the production of important vitamins and short-chain fatty acids, said Dr. Firoozi.

“Short-chain fatty acids are the main nutrients for your intestinal cells and are vital to cell function in general,” he added.

Which fruits and veggies are best for bacterial diversity? 

When it comes to figuring out which fruits and vegetables are best for the gut microbiome, Richard said variety is the name of the game.

“Variety in type and families of fruits and vegetables, as well as variety in the ways they are prepared (and) variety in frequency on a daily, weekly, and seasonal basis as applicable and accessible,” she added.

While most fruits and vegetables are rich in soluble and insoluble fibers and have beneficial components, Richard said those that are especially supportive of gut health include:

  • vegetables in the brassica family — Brussels sprouts, cabbage, kale, arugula, asparagus, and broccoli
  • vegetables in the allium family — chives, onions, garlic, leeks, shallots, and scallions
  • fermented vegetables such as kefir, kimchi, sauerkraut, yogurt, miso, and natto
  • fruit such as bananas, figs, pears, berries, apples, apricots, apples, and kiwis

“If you are experiencing bloating, irritable bowel syndrome (IBS), or other gastrointestinal issues that inhibit consuming a diverse variety of fruits and vegetables, you may benefit from working with a registered dietitian nutritionist in order to prep and prime your gut and body to optimally benefit from the introduction and implementation of this variety of fruits and vegetables.”
— Monique Richard, registered dietitian nutritionist

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