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The 12 Worst Foods for Gut Health


One of the roles of the gut is digesting food. The gut contains about 100 trillion bacteria that weigh up to 5 lbs, which is ten times more than human cells. Gut bacteria aid digestion by breaking down sugar polymers into simple glucose. Another role of the gut is eliminating harmful pathogens from the body. The gut is able to do so since it accommodates the immune system.

According to Healthline, 70% of the immune system is in the gut. For your gut to continue fighting pathogens and breaking down food uninterrupted, you must avoid certain foods. You are probably wondering which foods those are. Without further ado, here are the 12 worst foods for gut health.

12. Dairy Products

Even if you are not lactose intolerant, dairy products can still affect your gut health. They cause inflammation in the gut, which leads to a leaky gut. When you develop a leaky gut, the space between cells is widened in the intestines. The space between the cells is important since it allows for the passage of nutrients into the bloodstream. However, as the spacing becomes wider, partially digested food or other unwanted substances leak out of the gut into the bloodstream. As more foreign substances leak into the bloodstream, the immune system fights them off.

The issue arises when the immune system cannot distinguish between foreign invaders and its cells. As a result, it fights all the substances, including its cells. Besides destroying the good cells, another challenge occurs as more substances continue leaking into the bloodstream. Your immune system gets overwhelmed, and the accumulation of foreign substances will further cause inflammation. Some symptoms of a leaky gut include constipation, fatigue, headaches, joint pain, and skin problems like acne, rashes, and eczema.

11. Alcohol

Alcohol is quite safe as long as you drink it in moderation. According to MyHealthfinder, drinking in moderation means women should have one drink or less, while men should have two drinks or less in a day. If you exceed the recommended number of drinks, you will negatively affect your gut. One of the effects of alcohol is acid reflux. It triggers this problem by relaxing the lower esophageal sphincter. The lower esophageal sphincter’s role is to prevent acid from the gut from backing up into your esophagus, and its role gets hindered when alcohol relaxes it.

If you continue drinking heavily, the acid reflux could result in severe complications like strictures or esophagitis. The other effect of excess alcohol is diarrhea. We have established that the gut contains bacteria, both bad and good. Excess alcohol interferes with the balance of the bacteria in the gut. As a result, the gut will house more bad bacteria than good ones. The bad bacteria cause inflammation and irritation in the gut. Since the bad bacteria outnumber the good ones, the gut is forced to get rid of them along with your stool.

10. Red Meat

One of the effects of eating too much red meat is heart disease. It causes this condition by altering the composition of gut microbiota. The substance in red meat responsible for changing the composition of gut microbiota is L-carnitine, which is also a chemical compound found in energy drinks. When the bacteria digest L-carnitine, it turns into a compound called trimethylamine-N-oxide (TMAO). TMAO leads to clogged coronary arteries, which ultimately lead to heart attacks. To make matters worse, L-carnitine triggers the multiplication of bacteria that breaks it down, which means more TMAO will be generated. Another effect of this food is inflammation in the gut. All mammals except humans naturally produce a carbohydrate called Neu5Gc. Since humans do not produce the carbohydrate, they obtain it from red meat.

If you eat too much meat, the carbohydrate will accumulate, and your immune system will perceive it as a threat. As a result, the immune system will generate several antibodies against it. Eventually, the excess response by the immune system causes inflammation since some of the tissues get injured in the process. Lastly, it causes colon cancer. According to Positive Gut, you risk getting colon cancer by 18% for every 50g of meat you consume a day. Red meat has a chemical called haem, which is broken down in the gut. When it is broken down, N-nitroso chemicals are formed. N-nitroso chemicals damage the cells that line the gut, which leads to colon cancer.

9. Tap Water

The water that comes from the tap may be treated or untreated. Treated tap water contains chlorine. Chlorine effectively eliminates bacteria and viruses in water, which means the chlorinated water will be free of harmful microorganisms. Since chlorine kills the microorganisms in water, it will also kill them in the gut. Unfortunately, the gas kills bad bacteria along with the good ones. With less good bacteria, the gut will be ineffective in digestion and combating harmful bacteria. Since chlorine is dissolved in water, a chemical reaction occurs, which results in the formation of Trihalomethanes (THM).

THM is harmful since it destroys cells and causes colon and rectal cancer. To mitigate the effects of chlorine, it would be best to get rid of it through reverse osmosis or a water filter. Your water will still be safe without chlorine since it will have killed all the germs in the water. On the other hand, untreated water is bad for gut health since it hasn’t been treated to eliminate harmful microorganisms. That means you will introduce more bad bacteria into the gut. Your immune system will release antibodies against them and destroy the good ones too. Consequently, you will suffer from diarrhea, nausea, and gastrointestinal problems. To treat untreated water, you may use a water purification filter or boil it.

8. Processed Foods

Not all processed foods are harmful. Food is processed for it to be easily broken down in the gut. Some of the healthy processed foods that are safe include tofu, nuts, and canned beans. Instead, you should avoid or reduce your intake of highly processed foods like frozen pizza, sausage, cookies, etc. These foods do not provide ideal conditions for healthy bacteria to prosper. That is because they are low in fiber, something the good bacteria need to multiply. Another way they interfere with the composition of gut bacteria is the presence of additives in them.

These additives are responsible for gut inflammation. Limiting or eliminating processed foods is not easy, but that can be done. If you want to know whether a certain food is highly processed, begin by looking at its ingredients. A long list of ingredients suggests it is highly processed due to the high number of ingredients. Also, if most ingredients are hard to pronounce, it is safe to assume it is processed. Since most restaurants serve processed foods, you could begin by cooking more at home. Lastly, opt for minimally processed meats like chicken breast and not highly processed ones like sausages.

7. Artificial Sweeteners

They are usually found in soft drinks, snack foods, and sugar-free candies. Some people prefer them to sugar since they do not pack any calories. Additionally, they are even sweeter than sugar. As healthy as they may seem, they are bad for gut health. Artificial sweeteners turn healthy bacteria in the gut into harmful microbes. For instance, saccharin (found in soft drinks) causes healthy bacteria like E. faecalis to be pathogenic. When that happens, you will experience serious health issues such as blood poisoning. E. faecalis can cross the gut wall and enter the bloodstream, and that is how you end up with blood poisoning. Besides infecting the blood, the bacteria can also affect the spleen, liver, and lymph nodes.

6. Fried Foods

Fried foods in fast-food restaurants tend to be tasty and crunchy, thanks to the use of hydrogenated oils. Since they are fried with hydrogenated oils, they contain a lot of fat. Of all the macronutrients, fat takes the longest to be digested. So if you have a lot of fat in your system, the gut will be overwhelmed by the amount to digest. As a result, the fat will stay in the gut for a long time, leading to bloating, stomach pain, and nausea. While the fat stays in the gut for a long time, it impairs the gut microbe by decreasing healthy bacteria and multiplying unhealthy bacteria. As a result, you may contract diabetes, heart disease, and cancer.

5. Gluten

Gluten is a protein found in grains like wheat and barley. The protein is insoluble and hard to digest, which means it accumulates in the gut just like fats. As gluten accumulates in the gut, it significantly reduces the number of good bacteria. Besides interfering with the bacteria composition, it affects the immune system. For instance, it causes the immune system to damage the colon, thereby hindering its ability to absorb nutrients. Some of the symptoms you may experience after the colon has been damaged include anemia, constipation, weight loss, and bloating. These symptoms will be especially severe in people who have Celiac disease.

4. Fructose

Fructose is the sugar found in most fruits. You may be wondering if your gut will be affected after consuming a lot of fruits rich in the sugar. Fortunately, you will not be affected by fructose no matter how many fruits you eat. Instead, we are referring to the fructose from corn starch which manufacturers use in sodas and candies. When consumed in excess, you could contract the non-alcoholic fatty liver disease (NAFLD). It occurs when the sugar reaches the gut and disrupts the epithelial barrier that protects internal organs from bacterial toxins. The disease affects the liver more than the gut. If not immediately addressed, the disease could progress to severe illnesses like liver cancer and cirrhosis.

3. Soy

Typically, soy is touted as a healthy alternative to meat and milk. That explains why some vegetarians rely on it for protein, but it is unfortunately bad for gut health. Soy is not easily digested since it contains some proteins that our bodies cannot readily absorb. Therefore, it is specially designed for herbivores since they can digest the proteins in it. Since it cannot be digested, it stays in the gut for a long duration, leading to gut infections. Another negative effect of soy is that it prevents the absorption of certain vital minerals like iron, calcium, and zinc. The reason for this phenomenon is that it is high in phytic acid, which is a digestion inhibitor.

2. Farmed Fish

Farmed fish is bad for our guts, and that has to do with what the fish are being fed. Some farmed fish are fed manufactured fish filets that contain fishmeal. The drawback of fishmeal is that it is often affected by high levels of cancer, which makes it dangerous to eat such a fish. As a result, some people have substituted fishmeal with grains and soy. Grains and soy seem like solid substitutes, but they are also bad for gut health. The substitutes cause the fish to gain weight rapidly. As a result, these fishes are high in fat and not the good kind like Omega-3. Due to the high-fat content, you will experience inflammation in the gut.

1. Nightshades

Foods that belong to the nightshades family include tomatoes, bell peppers, potatoes, and eggplant. Although they are often considered part of a healthy diet, they contain a key ingredient that can trigger gut issues. The ingredient present in the nightshades are alkaloids which contain nitrogen. Alkaloids protect the nightshades from insect attacks since they act as natural insect repellents. When you consume too much of this food group, you will experience intestinal disorders, inflammatory problems, and digestive upset. Additionally, some people can develop allergies to certain nightshades, which involve symptoms like itching and breathing difficulties.


Although these foods are bad for gut health, it does not mean you have to eliminate them completely from your diet. You only need to consume them in moderation; after all, these foods are still beneficial to the body. For instance, red meat is high in iron. If you want to enjoy good gut health, you should consider foods like yogurt, olive oil, almonds, bananas, etc.

Dana Hanson

Written by Dana Hanson

Dana has extensive professional writing experience including technical and report writing, informational articles, persuasive articles, contrast and comparison, grant applications, and advertisement. She also enjoys creative writing, content writing on nearly any topic (particularly business and lifestyle), because as a lifelong learner, she loves to do research and possess a high skill level in this area. Her academic degrees include AA social Sci/BA English/MEd Adult Ed & Community & Human Resource Development and ABD in PhD studies in Indust & Org Psychology.

Read more posts by Dana Hanson

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