Bacteria and other microbes in the gut help the body digest food. These bacteria may also play an important role in helping the body fight harmful bacteria, yeast, and other microbes.

Foods that promote gut health can feed good bacteria or add more helpful bacteria to the gut. Less healthful foods may promote gastrointestinal problems or damage gut bacteria.

The effect of different foods on gut health depends on numerous factors, including a person’s overall diet and food sensitivities. Someone who is sensitive to certain foods, for example, might have gut health issues due to a food that would otherwise be gut-friendly.

In this article, learn about the worst foods for gut health, why they contribute to gastrointestinal problems, and more. The following foods may undermine gut health for some people:

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Food from animals — including meat, dairy, and eggs — offer various health benefits. They are rich in protein and other nutrients, such as choline. However, people with diets very high in animal protein may experience harmful changes in their gut microbiome.

A 2023 review suggests that people who eat lots of animal protein may have less beneficial gut bacteria and more harmful gut bacteria that researchers associate with obesity.

Another 2023 review of 11 studies involving 4,302,554 people highlighted an association between meat intake and risk of inflammatory bowel disease (IBD). For every additional 100 grams (g) daily of meat, people had a 38% higher risk of IBD.

A 2019 study suggested that red meat may be especially unhelpful, as it raises levels of trimethylamine N-oxide (TMAO). TMAO is a byproduct of gut bacteria. Researchers link high TMAO levels to a higher risk of heart attack and stroke.

FODMAP is an acronym that stands for:

  • fermentable
  • oligosaccharide
  • disaccharides
  • monosaccharides
  • polyols

High FODMAP foods may be fine for many people to eat but may cause gastrointestinal problems in people with bowel issues, such as irritable bowel syndrome (IBS).

Fermentable foods, those that contain simple sugars, and those that contain sugar alcohols may irritate the stomach. Some high FODMAP foods include:

  • processed foods containing high fructose corn syrup, sorbitol, and other artificial sweeteners
  • fruit juices
  • xylitol, honey, and many other sweeteners
  • cheeses
  • white bread and pasta

However, many highly nutritious foods, such as apples and asparagus, are also high FODMAP foods.

People following a low FODMAP diet may wish to try an elimination diet. This process means cutting out and slowly re-adding foods to see which ones may cause gut symptoms.

Farmers, especially those with large-scale operations, may treat animals with antibiotics to reduce the risk of serious infections.

The use of antibiotics remains controversial, and some European countries have strict regulations controlling this practice.

Excessive exposure to antibiotics, especially in a person or animal who is not sick, may promote antibiotic resistance. This happens when bacteria with repeating exposure to antibiotics evolve to resist the drugs.

Antibiotics kill bad bacteria but can also kill helpful bacteria in the gut. Some people choose to take probiotics when using antibiotics to help prevent side effects.

Fried foods may be harder for the body to digest. People often cook them in oils rich in saturated and trans fats that may further irritate the stomach, causing diarrhea, gas, and stomach pain.

Fried foods may also lower the diversity of a person’s gut bacteria.

The American Liver Foundation recommends that people with conditions affecting the liver should avoid or limit fried foods.

The complex colony of organisms that live in the gut can affect various aspects of health.

When the body does not have the right balance of bacteria, certain organisms may grow out of control, affecting the risk of fungal and other infections.

For example, someone taking antibiotics may experience changes in their gut bacteria that make them more vulnerable to yeast infections.

According to a 2018 article, low gut bacteria diversity may link to various health conditions, including:

Plenty of nutritious foods may help promote gut health. Food groups that may be especially helpful include prebiotics, which helps feed good bacteria, and probiotics, which can add beneficial bacteria to the gut.

Prebiotic foods

Prebiotics are foods or food ingredients that the body does not digest. Instead, bacteria ferment them and use them for food.

Most prebiotics are a type of fiber, but not all fibers are prebiotics. This helps explain why some forms of fiber may be better for gut health than others.

Some healthful prebiotic foods include:

Probiotic foods

Probiotics contain healthful bacteria. Some examples of probiotics include:

  • cultured yogurt
  • cultured cottage cheese and other milk products with bacteria cultures
  • fermented foods, such as:

Some prebiotics and probiotics are also high FODMAP foods, so people may need to examine their dietary goals when deciding whether to consume each food.

No single food is a magic key to good gut health. Some fermented foods, which are often popular probiotic choices, may actually worsen gut health in people on low FODMAP diets.

Other foods, such as red meat and fried foods, may be best to avoid or reduce to improve gut health.

People hoping to improve gut health can talk with their doctor or dietitian about their specific gut health goals. A trial-and-error approach often produces the best results.