The Worst Foods for Gut Health

When it comes to health, the talk of the town lately has been the gut microbiome. Every nutrient you take in from every bite you eat has to pass through the gut microbiome so that it can be broken down and used by your body so the gut’s importance can’t be understated. Just the way that foods like kimchi, yogurt, sauerkraut and miso can help this system, there are foods that can damage it. So let’s take a look at what these foods are and why we should avoid or limit them. 


Red Meat

Red meats are a flavorful favorite on many dinner plates. As you may already know, steaks, bacon, and the like aren’t exactly what we’d refer to as health foods. In addition to their fat and cholesterol content, a compound found in red meats called L-carnitine can negatively affect the gut microbiome. The change results in the production of trimethylamine N-oxide which has been found to increase heart attack and stroke risk. 

Red meat is also correlated with diseases like colorectal cancer and inflammatory bowel disease. It may seem severe compared to the typical American diet, but The Cleveland Clinic recommends no more than 1-2 servings of red meat per week and only 3 ounces of red meat per week for those with heart disease or high cholesterol. 


Fried Foods

Everyone knows that fried foods are bad for you at this point. We normally only think of the damage they can do in terms of their saturated fat content but it turns out they can be damaging to our gut health as well. 

A randomized controlled trial to determine the exact effects of fried foods on the gut microbiome found that fried meat intake lowered microbial community richness. It additionally found that fried meat intake impaired glucose homeostasis, and increased intestinal endotoxin and systemic inflammation levels by influencing the gut microbiota and microbial-host cometabolites.


Artificial Sweeteners

In the last few years, alternative sweeteners have skyrocketed in popularity. Although they are low in calories, many people question their health effects, especially artificial, non-nutritive sweeteners. Data from the National Institute of Health indicates that sucralose and saccharin specifically might have a detrimental effect on gut bacteria. 

With this in mind, alternative sweeteners are a great way to ramp down your sugar intake. But they shouldn’t be seen as a consequence-free alternative to use without limits. 


Refined Sugar

We previously covered how excessive sugar consumption can lead to higher blood pressure, inflammation, weight gain, diabetes, and fatty liver disease. In addition to all of those reasons, you’ll want to avoid excessive sugar intake to protect your gut. 

Studies on the matter have found that excessive sugar intake can disrupt gut microbiota, increase inflammation and lead to the development of metabolic dysregulation. Cutting back on sugar has proven difficult for many so we’ve put together a full list of strategies to help you out



Alcohol, like many other things on this list, is damaging to our health and has no nutritional benefit to speak of on its own. In terms of gut health, frequent drinking leads to intestinal inflammation, causing changes in intestinal microbes. These changes further lead to permeability of the intestines. 



Caffeine is actually a bit of a mixed bag here. A healthy amount of coffee (containing 400mg or less caffeine per day) has been shown to be beneficial to the gut microbiome. A small abstract of 34 people presented at the American College of Gastroenterology annual meeting in 2019 determined that the microbiomes of regular coffee drinkers were significantly healthier than participants who drank little or no coffee. It’s also shown some benefit in preventing chronic liver disease obesity, metabolic syndrome and type 2 diabetes. 

The downside is that caffeine can irritate the bowels and cause stomach pain for people who are more sensitive. An additional caveat is that the source of caffeine matters as well. Artificial sources of caffeine like energy drinks won’t provide the same gut health benefits and tend to come with loads of refined sugar which is damaging to the gut and generally unhealthy. 


Processed Foods

Food processes such as milling, extrusion, and hydrogenation result in products that are affordable and convenient. However, these foods are often high in salt, fat, and sugar while being low in fiber and other necessary nutrients. 

Because processed foods run such a wide range, it’s hard to find much concrete data on how they affect the gut microbiome but in a 2021 Prospective Urban Rural Epidemiology (PURE) study, Ultra Processed Food intake was associated with a higher risk of Inflammatory Bowel Disease, specifically for Crohn’s disease. 


Refined Grains

Refined grains allow bread and pastries to be light and fluffy but this refining process also strips them of fiber, vitamins, and minerals. Whole grains have been shown to provide health benefits including to the gut but you may be wondering if that means the opposite is true for refined grains. Do they harm gut health? 

Scientists conducted a controlled study where participants ate identical meals down to serving size, meat content, and vegetable content with the only variable being refined vs whole grains. Those who ate the whole-grain diet had an increase in Lachnospira, the bacteria that produces short-chain fatty acids had a decrease in the pro-inflammatory bacteria, Enterbacteriaceae. Health markers were better for those who ate whole grains during this study but it is difficult to definitively say that refined grains cause absolute damage. 


Bottom Line

The gut microbiome is increasingly coming into focus in discussions around health. Most of the time we discuss all of the benefits of gut-healthy foods like kimchi, yogurt, and the like but there are a few foods that should be avoided to protect the gut. 

This article is provided for informational purposes only and is not intended to be used as medical advice. If you have immediate concerns about your health, please seek the help of your physician. 

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent disease.