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A 16-Week Vegan Diet Can Do Wonders for Your Gut Microbiome

Health + Wellness
A vegan diet can improve your health, but experts say it's important to keep track of nutrients and protein. Getty Images

By Dan Gray

  • Research shows that 16 weeks of a vegan diet can boost the gut microbiome, helping with weight loss and overall health.
  • A healthy microbiome is a diverse microbiome. A plant-based diet is the best way to achieve this.
  • It isn't necessary to opt for a strictly vegan diet, but it's beneficial to limit meat intake.

New research shows that following a vegan diet for about 4 months can boost your gut microbiome. In turn, that can lead to improvements in body weight and blood sugar management.


But it doesn't mean you need to swear off the meat and dairy entirely.

It's significant, however, that moving toward a more plant-based diet is probably the healthiest choice.

The research, led by Dr. Hana Kahleova, MD, PhD, of the Physicians Committee for Responsible Medicine, was presented this week at the annual meeting of the European Association for the Study of Diabetes in Barcelona, Spain.

Researchers studied 147 participants, randomized into two groups. One followed a low-fat vegan diet. The other made no changes to their diet.

After the 16-week study was completed, researchers reported the vegan group saw their body weight, fat mass, and visceral fat levels go down.

"We expected to see changes in the gut microbiome on a plant-based diet," Kahleova told Healthline. "However, it was surprising to see how fast the changes occurred and how profound they were."

When asked what the biggest takeaway of the research is, Kahleova was unequivocal.

"Eat more plants," she said. "They contain fiber that boosts the gut microbiome and metabolic health."

What’s the Gut Microbiome?

Because this research deals with how a vegan diet boosts the gut microbiome, it's worth knowing what the gut microbiome actually is.

The microorganisms that live in the digestive tract, when properly balanced, promote a healthy digestive tract, along with the immune system, bowel movements, metabolism, and hormones that help with appetite regulation.

But when the microbiome is unbalanced, things can get out of whack.

"What's happened is we've moved to a more Western diet that includes such highly processed foods like bread, rice, pasta, and a lot of animal meat," explained Sharon Zarabi, RD, CDN, CPT, bariatric program director at Lenox Hill Hospital in New York.

"That has changed the harmony of the microbiome," Zarabi told Healthline. "A lot of the gut bacteria are imbalanced, and that can lead to exacerbated symptoms of irritable bowel syndrome, decreased immune system, and even proliferation of cancer cells."

Kristin Kirkpatrick, MS, RDN, manages wellness nutrition services at the Cleveland Clinic Wellness Institute in Ohio. She says the researchers' findings aren't surprising.

"Multiple studies show benefits to a plant-based diet. One of the greatest predictors of good gut health is a variety of antioxidant-, phytonutrient- and fiber-rich foods. Plants provide the bulk of these," Kirkpatrick told Healthline.

Plant-Based or Vegan: What’s Best?

While the study specifically looked at people who followed a vegan diet, dietitians say that while a plant-based diet is the healthy way to go, it isn't necessary to follow a strict vegan diet.

"When we're eating a more diverse plate of food that has different macronutrients, such as protein and fiber and complex carbs and healthy fat, we get to increase the diversity of the microbiome," Zarabi said.

"A vegan diet that promotes high-fiber foods that come from plants will improve the gut microbiome. But when we start to take out all animal protein, we tend to limit ourselves with where our protein is coming from. If you're [eating] from a vegan diet, it's mostly coming from beans and some vegetables. So it's really important to make sure you don't fall short on any nutrients," Zarabi said.

While it's hard to argue with some of the ethical reasons for embracing veganism — including animal welfare and reducing one's carbon footprint — it's still crucial to monitor one's nutrition.

"A vegan diet can be less advantageous if all your foods are frozen dinners and white grains," Kirkpatrick said. "Doing your research and meeting with your doctor or dietitian to help you get started is recommended."

You Are What You Eat


It might seem daunting to make the pivot from burgers and fries to lean protein and veggies. But it isn't impossible.

"I think the first step is familiarizing yourself with the different vegetables that are out there, specifically the vegetables that have the prebiotic fibers," Zarabi said. "These are the initial phase of what probiotics feed on: indigestible fibers that help encourage the growth and proliferation of the probiotics."

High-prebiotic foods include asparagus, onions, Jerusalem artichokes, cabbage, garlic, cashews, lentils, and chickpeas.

Zarabi cautions that when these foods are unfamiliar to the gut, initial side effects could include bloating and gas as the body learns to adapt.

"If you have those symptoms in the beginning, don't get turned off just yet," she said. "Give your body some time to adapt to the changes. If you're still feeling a lot of GI distress, you may want to work with a dietitian to figure out which vegetables or prebiotics are better for you."

When planning a meal, it's helpful to think in terms of thirds.

A third of the plate should be vegetables, a third should be lean protein sources, and a third should be complex carbs, such as sweet potatoes, beets, quinoa, bran, and oats.

There's also room for healthy fat, such as olive or avocado oil, because they help improve heart health.

Kirkpatrick recommends entirely cutting out red and processed meat, or at least limiting these products to twice a month.

"You are what you eat, so what goes into your body affects your health outcomes," Zarabi said.

"Eat as close to nature as possible," she said. "Think about what you're putting in your body. How many steps did it have to go through to get to you? Choose foods that are close to nature, the ones that include one ingredient. They're the best for you."

Reposted with permission from our media associate Healthline.

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