From Probiotic to Processed: The Best and Worst Foods for Your Gut

Rory Batt MSc: Nutritionist
From Probiotic to Processed: The Best and Worst Foods for Your Gut - The Meal Prep Market

This one goes out to all of you who are experiencing digestive symptoms, who feel lost in their diets and just don’t know what is behind the discomfort.

Food can be your best friend or your worst nightmare depending on your makeup and what foods you eat.

What goes in and out of the body may not seem like a particularly big deal. If we think of food in the reductionist way that it is nothing more than simply the energy and nutrients that it contains, then we’d be right to assume that what we eat doesn’t really matter, so long as we don’t eat too much of it.

But food is much more than that. It has functions, and it affects our health in ways which are so much more than just down to the energy they contain. It all has to do with how these foods are affecting our guts.

We’re going to cover how to improve gut health, by identifying the good, the bad and the ugly when it comes to foods.

How Food Affects the Gut

The gut is the crucial barrier that separates our inner world from the outer world, and provides a means of defense and safe exchange of essential components, such as nutrients.

You want nutrients to go in, and pathogens like bacteria and viruses to stay out.

A person's diet and the foods they eat (or don’t eat) greatly impacts the structural, and functional aspects of their gut, as well as their overall health.

A lot of junk foods can be highly inflammatory, which can not only cause functional disturbances in gut health, such as diarrhea (over time this can lead to nutrient deficiencies), but also lead to structural damage of the intestinal wall.

Damage to the intestinal wall is not good. It’s known as a leaky gut. When pathogens can leak through the gut, it can cause immune problems, and even autoimmune diseases. Even food proteins can trigger this response too (Gluten).

Bad food = aggravates immune system = inflammation

Junk foods, that are rich in sugars and trans fats can negatively affect the delicate balance of beneficial : harmful intestinal bacteria (1), (2).

When the composition of intestinal bacteria shifts, in a negative way it’s known as dysbiosis.

This creates a highly inflammatory environment in the gut that can lead to gastrointestinal issues, such as bloating, abdominal pain, indigestion, constipation, diarrhea, flatulence as well as structural damage to the intestinal lining.

The effects of bad foods go far beyond just the digestive system though. Inflammation in the gut, and a leaky intestine also opens the rest of the body to be affected by inflammation, and the immune fallout that occurs from pathogens and proteins (like gluten) that shouldn’t be in there.

What you’d expect from this is things like:

  • Fatigue
  • Brain fog
  • Anxiety
  • Depression
  • Lack of Focus
  • Bad sleep
  • Generally feeling crappy

A lot of natural foods however can soothe and positively regulate the intestinal environment. However, it is worth noting that even a lot of healthy foods can aggravate pre-existing gut imbalances - such as foods high in FODMAP’s, Specific Carbohydrates, foods high in Oxalates, and high histamine foods. These healthy foods need to be excluded and carefully re-introduced when the gut has sufficiently recovered.

The Worst Foods For Gut Health

If you want to know the first step in how to heal your gut, just avoid these foods.


Sugar feeds ‘bad’ bacteria, which can lead to an overgrowth of yeast like Candida (3). This isn’t inherently bad, just when it becomes overgrown it can be a problem. There are other species of bacteria which feed off sugar, causing overgrowth. Small intestinal bacterial overgrowth is a situation where bacteria can become overgrown in the small intestine, leading to some of the symptoms we outlined above, including digestive and cognitive issues.

Sugar is super inflammatory, partly due to the effects it has on the gut ecosystem. Inflammation underlies just about every chronic and functional condition, so it’s important to keep it under control.

You’ll find sugar in foods like sweets, cakes, biscuits, sodas, energy drinks.

Artificial sweeteners

These are also known as NCAS (non-caloric artificial sweeteners) under names like Splenda and Nutrasweet. These alter the composition of the intestinal microbiota, which is the collection of various microorganisms in the gut.

Disturbing the balance of gut microbes can cause a shift in metabolism in the body. It leads cells to become intolerant to glucose, which can lead to the development of diabetes (4).

You’ll find NCAS in things like diet coke, other fizzy drinks, and sachets added to tea / coffee.

Trans Fats

These are the kind of fats that are found in cakes, biscuits, crackers and some crisps. One way that trans fats can harm the gut is by increasing inflammation in the body.

Studies have shown that trans fats can trigger an inflammatory response in the gut, which can lead to a range of health problems (5). Chronic inflammation is associated with a variety of gut conditions, including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), and leaky gut syndrome.

Trans fats can disrupt the balance of the gut microbiome, leading to an overgrowth of harmful bacteria and a reduction in beneficial bacteria. This can contribute to gut dysbiosis, a condition in which the gut microbiome is imbalanced and may cause digestive symptoms like bloating, gas, and diarrhea.

They can also reduce the absorption of essential nutrients, such as omega-3 fatty acids, which are important for gut health. This can lead to deficiencies that can contribute to inflammation and other gut problems.

Fruit & Veg

Even healthy, natural foods can damage gut health…..

Because of pesticides.

If you are serious about gut health / need to heal it, you need to either go organic or simply just buy the Dirty Dozen List of fruits and vegetables organically.

The ‘Dirty Dozen’ are common foods which harbor harmful pesticides. It is therefore advisable to source these organically.

The Dirty Dozen list

The ‘Clean Fifteen’ are foods which are typically low or free of harmful pesticides.

The Clean 15 List

Organophosphates (Endocrine Disruptors) have been identified as pancreatic toxicants, leading to pancreatitis, a condition to which exocrine secretions (enzymes) are affected. This is BAD for digestive health…….

Glyphosate, an organophosphorus herbicide, is widely sprayed on conventional produce worldwide. It is also an ingredient in Roundup, the weedkiller produced by the nefarious biotech company, Monsanto.

Glyphosate lays the foundations for a leaky gut. This happens first through the depletion of beneficial bacteria, and overgrowth of pathogenic bacteria. These pathogenic bacteria cause inflammation, damaging the lining of the gut wall causing it to leak. This not only compromises our digestive health, but our overall health and wellbeing.

Glyphosate is implicated in the depletion of beneficial bacterial strains such as Bifidobacteria and Lactobacillus, and increasing the number of pathogenic bacteria (6).

The Best Foods For Gut Health


Ghee is a great way to love your gut. As ghee is a concentrated form of butter, it is densely packed with a very beneficial compound for good digestion and outward health. Butyric acid (butyrate) is a type of short chain fatty acid (SCFA) which offers powerful support to the health of our cells and the health of our bacteria.

SCFA are used as fuel by our enterocytes (gut cells), to grow and repair to help us absorb precious nutrients and defend against invaders. This supports better digestion through improving the health of our intestinal lining. Our beneficial microbes are fuelled by butyrate, to strengthen our immunity. If our microbes are strong, abundant and diverse then our health is allowed to flourish.

By offering fuel to strengthen our beneficial bacteria, SCFA inadvertently help to block the growth of bad bacteria which undermine our digestion, immunity, energy, mood and ultimately quality of life.

If you are healing your digestive system, have food intolerances and an irritable bowel, Ghee should be a top consideration for your list of healing foods. Ghee maybe tolerable for most people as the dairy components of the butter have been clarified - the lactose, the casein and the whey.


These are one of the good gut health foods. Oats are a type of whole grain that are rich in dietary fiber, including both soluble and insoluble fiber, which makes them a great food for gut health. In particular, oats are high in a type of soluble fiber called beta-glucans, which have been shown to have numerous health benefits, including supporting gut health.

Beta-glucans are a type of prebiotic fiber, meaning that they serve as food for beneficial bacteria in the gut. When we eat foods that are high in prebiotic fiber, such as oats, these fibers reach the large intestine undigested and are fermented by the gut microbiota, producing short-chain fatty acids (SCFAs) that can help to support gut health.

Research has shown that beta-glucans in oats can help to increase the abundance of beneficial bacteria in the gut, such as Bifidobacteria, while also reducing the abundance of potentially harmful bacteria. This can help to improve gut health and support overall health and wellbeing.

Additionally, oats contain a variety of other prebiotic fibers, such as inulin and resistant starch, which can also support gut health by feeding beneficial bacteria and promoting the growth of a healthy gut microbiota.

Yoghurt (Probiotic)

Yoghurt is a great gut health food as it’s a rich source of probiotic bacteria. Probiotic bacteria are good for gut health because they can improve bacterial balance in the gut, reducing the growth of harmful bacteria and promoting the growth of beneficial ones. They can also improve digestion, enhance nutrient absorption, and strengthen the immune system.

The fermentation process used to make yogurt involves adding probiotic bacteria, such as Lactobacillus and Bifidobacterium, to milk. This is what gives yogurt it’s gut healing power. But this isn’t just for any old yogurt….

When choosing a yogurt for gut health, it is important to look for brands that contain live and active cultures of probiotic bacteria, as some yogurts may not have enough of these bacteria to have a significant impact on gut health. Some flavoured yogurts may contain added sugars, which can have a negative impact on gut health, so watch out for those.


Kimchi is good for gut health because it is a fermented food that is rich in probiotics, which are beneficial bacteria that can help support the growth of other beneficial bacteria in the gut. The probiotics in kimchi can help to improve gut health by reducing inflammation, promoting regularity, and enhancing immune function.

In addition to probiotics, kimchi is a good source of fiber, vitamins, and minerals. The vegetables used to make kimchi, such as cabbage, are high in fiber, which can help to promote the growth of beneficial bacteria in the gut. Kimchi is also rich in vitamin C, vitamin K, and other beneficial nutrients, which can help to support overall health and wellbeing.

Kimchi contains a range of spices and seasonings, such as garlic, ginger, and chili peppers, which can provide additional health benefits. Garlic and ginger are known for their anti-inflammatory and immune-boosting properties, while chili peppers can help to boost metabolism and improve digestion.


So there you have it. We’ve covered the foods that are good for gut health, and which ones to avoid. We’ve also outlined which foods to avoid to keep a healthy gut. This is just the first step in your gut healing journey, but one that will get it off to a flying start. Check out some of our other articles on eating Low FODMAP for more guidance on how to keep a healthy gut.

Back to blog

Leave a comment

Please note, comments need to be approved before they are published.

Some of our nutritious meal prep...