A healthy, balanced gut is the foundation for excellent health. That includes a diet filled with diverse, nutrient-rich foods that support your microbiome.

As a medical doctor specializing in gut health, I’ve helped thousands of patients eliminate potentially problematic foods and choose the best ones for their gut, immune system, and overall health.

While everyone’s body is different, in my experience, I’ve found certain foods have an impact on gut health more often than others, including some vegetables and other staples that might surprise you. This doesn’t mean you need to nix all these foods automatically, and most are fine in moderation. Pay attention to what foods may be taking a toll on your body, and work with your medical provider to figure out what could make the most sense for your diet.

1. Processed foods

While some processed foods can be part of a healthy diet, it’s important to note that 74% of processed foods on the market contain added sugar. They also often contain a lot of artificial colors, flavors, and unhealthy fats, which may negatively affect your gut health. Studies show animals fed a high-fat, high-sugar diet—very similar to what you’ll find in many processed foods—have a less diverse and less healthy range of gut flora.

2. Sugar

Of course, you know that added sugar is best kept to a minimum in your diet. But you might not know it could potentially affect your gut health, too. Animal studies find that sugar can slow down the production of specific proteins that help maintain the gut flora found in healthy people.

3. Alcohol

Research shows that drinking too much alcohol may contribute to imbalances in your gut flora and inflammation. It could also lead to dysbiosis or bacterial overgrowth, which may cause problems like poor digestion, acid reflux, and small intestinal bacterial overgrowth (SIBO).

With alcohol, quality and quantity matters. Drinking a glass of quality cabernet will affect your gut entirely differently than, say, a number of sugar-laden margaritas. Read my guide on how to make gut-friendly alcohol choices.

4. Dairy

About 65% of the world’s population has a reduced ability to digest lactose, the primary sugar in milk and other dairy products, after infancy. Gas, bloating, and diarrhea are some of the symptoms of lactose intolerance.

If you notice any negative symptoms within hours after eating dairy (headaches, fatigue, stomach pain, etc.), you may want to speak to your doctor about the possibility of lactose intolerance and potentially cutting back on dairy.

However, you might benefit from some cultured dairy products (such no-sugar-added yogurts and kefirs). These are probiotic foods that are easier on the digestive system and can support the growth and proliferation of your “good” gut bacteria.

5. Legumes

Legumes contain a number of nutrients, but they’re also notorious for causing gas, which leads to bloating, abdominal discomfort, and even pain. Legumes are additionally high in lectins, which can potentially interfere with the breakdown and absorption of nutrients, and may affect the intestinal flora.

That said, soaking or fermenting your legumes will minimize these problems, so they can be part of a healthy, gut-friendly diet.

6. Soy

Soy, another lectin-rich legume, can also be hard to digest, which may lead to bloating and abdominal pain. Some people do well with small amounts of fermented, non-GMO, organic soy, like tempeh or natto, which are friendlier to your gut.

7. Artificial sweeteners

Once positioned as a healthy alternative to sugar, we now know that artificial sweeteners are not greatfor your gut and overall health. Studies in mice show that sucralose, for example, can disrupt healthy gut flora and increase the number of inflammatory gut flora.

Bottom line.

While these are the foods that may potentially be worse for your gut, you might not need to avoid all of them completely. Just be sure to choose the highest quality products, such as cultured, organic, grass-fed dairy and fermented, organic soy, as examples. And remember, even a healthy food or drink can become unhealthy when you consume too much.