These Popular Diets Could Actually Be the Worst for Your Gut Health, According to a Recent Study

·4 min read
young woman who makes a heart shape by hands on her stomach.
young woman who makes a heart shape by hands on her stomach.

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Our gut health is incredibly important to our overall health and well-being. It can impact our chronic disease risk, mental health and even help us maintain a healthy weight. While we already know that certain foods can help—or hurt—our gut microbiomes, a recent study published in The American Journal of Clinical Nutrition provides further evidence about how our eating patterns are linked to our gut health.

The study was led by the team at Danone Nutricia Research (part of Groupe Danone, which sells many brands of yogurt in the U.S.) and followed 1,800 men and women ages 18 and older. The researchers tracked participants' eating patterns through a Food Frequency Questionnaire to determine which diets were most associated with the gut microbiome. The researchers also performed a retrospective analysis of data from the American Gut Project, the largest gut-health study to date in the U.S.

The study divided participants based on their five different eating patterns:

  • Plant-based: Primarily vegetarians and vegans who ate little to no meat and large amounts of high-fiber produce and whole grains. Through their FFQs, researchers calculated that people in this group had around 55% of calories from carbohydrates, 13% from protein and 28% from fat.

  • Flexitarian: Individuals who ate some meat and plenty of fiber-rich, plant-based foods. This group had 44% of calories from carbohydrates, 15% from protein and 36% from fat.

  • Health-conscious American diet: A dietary pattern that's rich in nuts, whole-grain cereals and dairy, but also high in added sugar and refined grains and low in vegetables. This group had 43% of calories from carbohydrates, 15% from protein and 37% from fat.

  • Standard American diet: This eating pattern is high in sugar-sweetened beverages and processed foods and has low diversity in plant-based foods and is low in fiber. This group had 43% of calories from carbohydrates, 16% from protein and 37% from fat.

  • Exclusion diet: This restrictive diet was the lowest in carbohydrates and highest in fats and animal products. This group had the highest-fat diet of any of the groups, clocking in at around 50% of calories, with 28% of calories coming from carbs and 18% coming from protein. This type of diet would include very little starchy foods or sugar (think: keto or paleo).

Researchers found that, out of the five eating patterns, those following a low-carb, high-fat exclusion diet had the lowest amount of Bifidobacterium, a beneficial type of gut bacteria. This is likely because these diets exclude fiber-rich carbs such as whole grains, fruit and potatoes, which help feed "good" gut bacteria. Conversely, those following a flexitarian diet had the greatest gut microbiome diversity—especially when compared to the standard American diet.

So, what does this all mean? Essentially, this research shows that certain diets are better for your gut than others. Miguel Freitas, Ph.D., vice president of health and scientific affairs at Danone North America, says, "This study showed that the flexitarian eating pattern that includes larger amounts of plant foods, yet doesn't totally eliminate animal foods, was associated with better overall diet quality and one of the approaches resulting in the most nourished gut."

And it's all about balance, Freitas adds: "This study together with previous research reinforces that a healthy gut microbiota is supported by a balance between all food groups, without restricting fiber-rich grain foods or animal products, like fermented dairy products, entirely."

If you want to nourish your gut, there are a few things you can do. First, eat plenty of fiber-rich foods such as fruits, vegetables and whole grains. If you eat meat, try cutting back a bit—we have plenty of delicious and crowd-pleasing meatless recipes (you can learn more about the flexitarian diet approach here). Lastly, don't follow an eating plan that eliminates an entire food group (unless it's been prescribed by your doctor). Your diet should have plenty of room for nutritious foods such as brown rice, whole-grain pasta, fruit, vegetables and potatoes—they're not only delicious, but your gut will thank you too.