6 worst foods for gut health, according to dietitians

Have you ever wondered how foods affect your gut? The answer basically revolves around your microbiome in the gut, which is home to trillions of microscopic organisms, such as bacteria, viruses and fungi. Don’t get it wrong, though – the gut microbiome with the right balance of good and bad is not concerning. Some microorganisms can be associated with disease, but others are essential for your gut health. 

Since your gut health depends on your microbiome, there are certain foods that may negatively impact its composition when taken too much. The foods you eat every day influence your gut health through the microbes that contribute to the unique function of your digestive system. 

Foods to avoid for a healthy gut

The absolute worst foods for gut health are those that contain high trans-saturated fat, provide very few redeemable nutritional qualities and can disrupt your well-balanced good and bad microbes. The following are six foods you must avoid to have a healthy gut:

1. Red meat

Eating red meats can increase N-nitroso chemicals in the body that are known to damage the lining of the bowel. Frequent consumption of red meat may cause gout attacks, indigestion and stomach bloat. Plus, it generally can trigger the development of gut bacteria that may clog arteries and increase your risk of heart disease due to its high saturation of fat and cholesterol. Diets that are high in red meat may also lead to colon cancer [1]. 

Dietitians recommend eating lean protein sources, such as fish or plant protein like beans and tofu, as alternatives. As it can be extremely hard to reduce red meat consumption due to its wide availability as a protein source in the regular market, you can choose leaner cuts of round, loin and sirloin for a healthier eating habit. 

2. Fried foods 

Fried foods are quite obvious to be part of the worst foods list. Hot oil-based frying can improve the texture and aroma of foods, making them more appealing to eat. However, it is an unhealthy cooking method because frying increases the energy density of foods. Therefore, energy intakes and deteriorates oils through oxidation and hydrogenation, causing a loss of unsaturated fatty acids, like linoleic and linolenic acids, but an increase in trans fatty acids, oil degradation and advanced glycation end products [2]. 

Fried foods 

Heated oil can be soaked up into fried foods and, when eaten, can negatively affect your existing gut bacteria. Even the types of oils usually used in deep frying, such as corn oil, canola oil or soybean oil, are all found to be notoriously unhealthy. Fried foods can also cause an upset stomach, a sign that all is not well in your gut microbiome. You may want to think twice before buying french fries or doughnuts next time. 

3. Heavily processed foods 

Frozen entrees, fast food, white bread and most canned veggies are just some examples of heavily processed foods that can damage the gut microbiome. As they are filled with unhealthy additives like sugar and preservatives and are low in fibre, these foods do not actually provide the ideal condition for the growth of healthy bacteria. The sugar allows bad bacteria to flourish even more, while having low fibre in your gut inhibits the growth of healthy bacterial colonies. 

In a review paper on the link between the Western diet and chronic diseases, they concluded that the high consumption of ultra-processed food could ultimately modify the gut microbiota and lead to inflammation. The Western diet described in the paper is characterised by high consumption of energy-dense and processed food [3]. 

Featured product offer
ProHealth Longevity Mitochondria Ignite™ with NT Factor®
  • 675 mg, 90 tablets designed for cellular and gut health.
  • Contains phosphoglycolipids, alpha-lipoic acid, magnesium, calcium, phosphorus, creatine monohydrate, and more.
  • Fights free radicals, harmful molecules that can cause oxidative stress and damage to cells.

4. Alcohol and other beverages

Frequent drinking of alcoholic beverages can change the makeup of the gut microbiome and promote the growth of bad bacteria in your gut, resulting in an imbalanced gut. An imbalanced gut can potentially manifest itself in increased gut permeability leading to several health issues. 

Additionally, coffee, soda and too much chocolate intake can increase the caffeine in your body that ramps up your intestines. The excitement that you feel in your digestive system after consuming caffeine often causes diarrhoea.

5. Dairy 

Yoghurt and kefir are well-known fermented dairy products that help the gut. However, unfermented dairy ones seem to disrupt your gut microbiome. Cow’s milk, as an unfermented, can alter the gut flora in unhealthy ways, leaving negative bacterial strains to colonise and push beneficial bacteria out.

If you are sensitive to dairy products or lactose intolerant, don’t risk putting your gut in a bad condition. There are dietary alternatives available, such as full-fat coconut milk or almond milk, that can still satisfy your thirst without thinking about negative drawbacks.

6. Fructose 

Fructose is the natural sugar of many fruits and may also cause issues with your gut microbiota when consumed frequently. It may increase gut permeability which potentially allows toxins to leave the digestive tract and enter the bloodstream.  

Artificial sweeteners such as sucralose, saccharin and the compound family of polyols are found to modify the number and composition of bacterial colonies in the gut. These changes can cause an imbalanced gut and allow the bad bacteria to flourish, harming good gut bacteria colonies. 

In a research study about the impact of the gut microbiome on maternal fructose, it was found that unabsorbed fructose is converted into hydrogen, short-chain fatty acids (SCFAs), methane and carbon dioxide by the gut microbiome. Moreover, a high-fructose diet can change the gut microbiome, causing gut dysbiosis and microbial metabolite disorder [4]. 

Foods to eat for a healthy gut

Many research studies have shown that changes to the gut microbiome can contribute to obesity, diabetes and cancer. This indicates that improving the makeup of our microbiome is essential in achieving a healthy gut. But how do we exactly help better our microbiome? The answer is simply eating the following foods that many experts and dietitians recommend. 

1. Bananas 

Regularly eating bananas can supply your gut with inulin–a type of fibre that nourishes good bacteria to grow. Bananas are a top-notch pick because of their high fibre and particular carbohydrate, both of which feed good gut bacteria.


2. Fermented foods

As much as you want to eat a lot of fibre to boost your metabolism, the bad news is that your body can’t break it down on its own. When you eat fibre, and it gets to your large intestine, your gut bacteria start to work by fermenting it. Then, the process of fermentation creates acids that allow feeding cells in your intestines while helping to protect your gut from harmful bacteria. 

Some fermented foods are also good sources of probiotics. To promote fermentation and aid in digestion, you must eat the following:

  • Kefir
  • Apple cider 
  • Certain aged cheeses
  • Dry curd cottage cheese
  • Farmer’s cheese
  • Fermented cottage cheese
  • Fermented vegetables
  • Plain yoghourt
  • Refrigerated miso 
  • Pickles with salt and not vinegar 
  • Sauerkraut 
  • Kimchi
  • Kombucha with no sugar 
  • Gluten-free tempeh 
  • Other various cultured products [5
Featured product offer
Vatellia Life Eaters Digest The Perfect Prebiotic
  • Contains 1,065 mg of a proprietary blend of different ingredients.
  • Has a soothing effect on the digestive tract.
  • Helps optimize nutrient absorption from the foods you consume.

3. Green tea and red wine

Green tea has a substance called polyphenols that may help fight excess bad bacteria like E. coli and manage the symptoms of inflammatory bowel disease (IBD) and peptic ulcers. Polyphenols also promote the growth of good bacteria in the gut. 

On the other hand, a study published by King’s College London reveals that people who drank red wine showed increased gut microbiota diversity which is a sign of good gut health, and it can be associated with lowered risk of obesity and bad cholesterol, this is in comparison to non-red wine drinkers [6]. 

4. Prebiotic foods

To diversify your gut microbes, you should eat prebiotic foods – refer to the compounds in food that induce the growth or activity of beneficial microbes. Prebiotics can significantly alter the makeup of microorganisms in the gut microbiome.

Some rich sources of prebiotics are:

  • Whole grains like oats, quinoa, barley and brown rice
  • Beans and lentils
  • Fruits such as berries, pomegranates, melon, apples, bananas and citrus fruits
  • Vegetables include broccoli, Brussels sprouts, spinach, cauliflower, lettuce, kale and leeks

Gut microbiome and longevity 

Immunity, digestion and metabolism are just a few of the responsibilities of the gut microbiome. When you look at it individually, each may seem quite basic; however, in the bigger picture, these three functions are essential for your overall longevity. With weak body immunity, you will obviously become at a high risk of developing chronic diseases. Meanwhile, continuous indigestion and poor metabolism can lead to obesity which is another culprit to fatal diseases. 

In fact, a research study found that healthy older adults have unique microbiome profiles, which can conclude that the gut microbiome may contribute to healthy longevity. Increased diversity and enrichment in butyrate-producing bacteria are associated with healthy aging and longevity [7]. Hence, it is essential to diversify the food you eat and avoid the absolute worst foods for gut health. 

Did you know that the world’s centenarians are also found to have robust and diverse microbiome communities in their gut? Another research discovered that over 160 centenarians with an average age of 107 have higher levels of several bacterial species that release molecules called secondary bile acids. The compounds are found to protect against any pathogenic species and regulate the immune response of the body. Thus, centenarians have stronger protection against diseases because of their diverse microbes. 

Featured product offer
Hello Health Belly Great – Pre/Probiotics + Mood
  • Blend of prebiotics and probiotics with 15 specially selected strains to support the brain-gut axis.
  • Includes essential ingredients such as Vitamin D3 and Methylfolate.
  • GMO-free, gluten-free, unsweetened, and formulated to be as pure as possible.

[1] https://www.nih.gov/news-events/nih-research-matters/gut-microbes-affect-harmful-compound-red-meat 
[2] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8740929/ 
[3] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6835660/
[4]  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4303825/ 
[5] https://www.umassmed.edu/nutrition/blog/blog-posts/2019/6/fermented-foods-for-gut-health/ 
[6] https://www.kcl.ac.uk/news/red-wine-benefits-linked-to-better-gut-health-study-finds 
[7] https://www.nia.nih.gov/news/unique-gut-microbiome-patterns-linked-healthy-aging-increased-longevity 

The information included in this article is for informational purposes only. The purpose of this webpage is to promote broad consumer understanding and knowledge of various health topics. It is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified health care provider with any questions you may have regarding a medical condition or treatment and before undertaking a new health care regimen, and never disregard professional medical advice or delay in seeking it because of something you have read on this website.