The worst foods for gut health

Knowing which foods are the worst for gut health is key to keeping your digestive system in top shape. Your gut's complex community of microorganisms significantly influences your overall health, and some foods can throw this delicate balance off. Here are the top culprits to avoid for better gut health!

Highly processed foods 

These products often contain a multitude of preservatives, artificial colours and flavours, and refined carbohydrates that can disrupt the balance of your gut microbiota. The lack of dietary fibre and an abundance of added sugars and fats in processed foods can also lead to inflammation and a decrease in beneficial bacteria.

Common examples of highly processed foods include:

• Crisps: High in saturated fats and salt, which can contribute to heart disease and high blood pressure. Also high in refined carbohydrates.

• Microwaveable Ready Meals: Often contain high levels of salt and preservatives.

• Instant Noodles: Typically high in sodium and artificial additives.

• Frozen Pizzas: High in calories, saturated fats, and sodium.

• Biscuits: Contain high amounts of sugar and trans fats.

• Cereal Bars: Often disguised as healthy but are high in sugars and low in fibre, contributing to spikes in blood sugar levels.

• Ice Cream: High in sugar and saturated fats, contributing to obesity and increasing the risk of heart disease.

• Chicken Nuggets: Processed meat high in fats and preservatives, linked to an increased risk of chronic diseases like bowel cancer.

• Fish Fingers: Often contain added salt and are coated in unhealthy fats.

• Sausage Rolls: High in saturated fats and salt.

• Dessert Cakes: High in sugars and unhealthy fats.

• Supermarket Sandwiches: Can be high in sodium, saturated fats, and additives.

• Breakfast Cereals: Many are high in added sugars and low in nutrients, contributing to unhealthy blood sugar spikes.

• Squash (Cordial): High in added sugars or artificial sweeteners.

• Chocolate Bars: High in sugar, fats, and calories.

• Processed Cheese: Often contains unhealthy additives and high levels of sodium.

• Vegetable Crisps: Although made from vegetables, they're often fried and heavily salted.

Refined carbohydrates 

Found in white bread, pastries, biscuits, cakes, breakfast cereals and other baked goods, refined carbohydrates can lead to a rapid spike in blood sugar and an altered gut flora composition. These quick-digesting carbs can also starve the gut of fibre, which is essential for a healthy microbiota.

Refined carbohydrates include:

• White flour

• White rice

• White pasta

Artificial sweeteners 

Though they offer a low-calorie alternative to sugar, artificial sweeteners may adversely affect the gut microbiota. Studies have indicated that they induce glucose intolerance by altering the gut microbiota.

Artificial sweeteners are commonly found in ‘diet’ products like:

• Diet soft drinks

• Sugar-free chewing gum

• Low-calorie yoghurts

• Sugar-free jellies

• Diet desserts

• Sugar-free squash or cordial

Trans fats 

Trans fats, or trans-fatty acids, are a type of unsaturated fat which come in natural and artificial forms.

Natural trans fats occur in the meat and dairy from animals such as cows, sheep and goats.

The artificial version is the worse of the two and may lead to heart health issues.

Both trans fats can promote inflammation and alter the composition of your gut microbiota, potentially leading to an imbalance.

Foods commonly high in trans fats include:

• Margarine

• Fast food

• Biscuits

• Cakes

• Fried chicken

• Doughnuts

Excessive caffeine 

In large amounts, caffeine can act as an irritant to the digestive tract, potentially causing heartburn and indigestion. It can also increase the motility of the gut, leading to diarrhoea and a disruption in the natural balance of gut flora.

Red meat 

High consumption of red meat has been linked with the presence of certain bacteria known to trigger inflammatory responses in the gut. The saturated fats in red meat can also contribute to cardiovascular problems and exacerbate issues within the digestive tract.

If you can’t stand the thought of giving up red meat, aim to reduce your consumption by not eating red meat on certain days (eg Mondays), or not having it at home or for lunches. Or consider switching it for chicken as another way to reduce consumption.

Hot spices

For those with a sensitive digestive system, spicy foods can be irritating to the gut lining. Capsaicin, the active component in many hot spices, can trigger acid reflux and lead to discomfort, especially when consumed in large quantities.

Sugary drinks 

High levels of sugar in drinks can disrupt the balance of gut bacteria, favouring the growth of harmful yeasts and bacteria. The lack of fibre in these beverages also does nothing to support the health of your gut microbiota. If you have a sweet tooth, aim for juice over lemonade.

Examples of sugary drinks include:

• Fizzy Soft Drinks (also known as soda or pop in the US)

• Fruit Squashes or Cordials: While they may contain fruit juice, they're typically sweetened with a large amount of added sugars or artificial sweeteners.

• Flavoured Waters: Marketed as a healthier option, but may contain high levels of added sugars.

• Sports Drinks: Designed for high-intensity athletes, yet commonly consumed without the exercise!

• Pre-made Smoothies: Often perceived as healthy, but many store-bought versions are high in added sugars.

• Iced Teas: These can be laden with sugars, masking the potential benefits of tea with high calorie content.

• Frappuccinos and Flavoured Coffees: Popular café drinks that are often more akin to desserts in their sugar content.

• Alcoholic Mixers: Drinks like pre-mixed cocktails and alcopops can be deceptively high in sugars.

• Milkshakes: Especially those from fast-food outlets, which can contain both added sugars and syrups, making them very high in calories.

Energy drinks

Similar issues to sugary drinks, but also high in caffeine. These can also lead to energy crashes, contribute to anxiety in some, and increase the risk of heart issues.

Fried foods 

The high fat content in fried foods makes them difficult to digest, increasing the workload on your digestive system. This can lead to stomach upset and a reduction in the production of beneficial short-chain fatty acids by gut bacteria.

Some examples of common fried foods to particularly avoid are:

• Fries

• Crisps

• Chicken Nuggets

• Onion Bhajis

• Spring Rolls

• Samosas

• Scotch Eggs

• Fried Chicken

• Fish and Chips

• Doughnuts

Corn syrup 

High-fructose corn syrup, found in many sweetened processed foods, can lead to an overgrowth of unhealthy bacteria in the gut. This sweetener can also cause inflammation and exacerbate conditions like irritable bowel syndrome.

Food commonly high in corn syrup include:

• Soft Drinks

• Sweetened Yoghurts

• Salad Dressings

• Ketchup

• Breakfast Cereals

• Biscuits

• Ice Cream

Alcohol 

Excessive alcohol intake is damaging to gut health and can lead to an overgrowth of harmful bacteria and compromise the integrity of the gut lining, leading to issues like leaky gut syndrome.

It is always better for your gut to not drink, but if you must drink, choose:

• Red wine: It contains polyphenols which act as antioxidants and interact with our gut microbes to create an array of healthy metabolites.

• Gin or vodka and soda: These are low in sugar and the soda contributes to hydration.

• Moderation: Each drink is compounding the problem further, so having two drinks instead of three is an improvement!

Emulsifiers

Emulsifiers can disrupt the gut barrier, potentially leading to conditions such as inflammatory bowel disease. They can alter the composition and function of the gut microbiota, leading to an imbalanced gut environment.

Foods commonly high in emulsifiers include:

• Mayonnaise

• Ice Cream

• Margarine

• Salad Dressings

• Processed Sauces

• Non-Dairy Creamers

• Packaged Breads

Sulphites 

Used as preservatives in some dried fruits, wines and other processed foods, sulphites can cause digestive discomfort for those who are sensitive and may negatively affect the gut microbiota.

Excessive salt 

High salt intake has been shown to lead to high blood pressure and may also harm the gut microbiota.

Try to stick with foods that are less than 120 mg of sodium per 100g and avoid foods which are more than 400 mg salt per 100g. However, this won’t always be possible with foods products such as sauces.

Foods high in salt include:

• Processed Meats: Such as bacon, sausages, hot dogs, and deli meats.

• Chicken: Particularly rotisserie chickens prepared in a supermarket.

• Canned Soups: Many varieties, especially those labelled as ‘condensed’ or ‘creamy’.

• Cheese: Especially processed cheeses like American cheese.

• Pickled Foods: Including pickles, olives, and other vegetables preserved in brine.

• Snack Foods: Such as chips, crackers, pretzels, salted nuts, and popcorn.

• Frozen Meals: Ready-to-eat meals often have high sodium levels for preservation and taste.

• Condiments: Soy sauce, ketchup, mustard, mayonnaise, and salad dressings can have high salt content.

• Bread: Often surprisingly high in salt.

• Sandwiches: Particularly supermarket versions with high salt bread, cheese and cured meats.

• Pizza: Due to its combination of salty dough, cheese, sauce and often including processed meat toppings.

• Tacos and burritos: Particularly due to the sauces, seasoning and cheese. Processed tortillas and taco shells themselves can also be high in salt.

• Canned Vegetables: Unless labelled ‘no salt added’, these often contain added salt for preservation.

• Instant Noodle Products: Including cup noodles and ramen packs.

• Breakfast Cereals: Some sweetened and savoury cereals are high in salt.

• Savoury Snacks: Such as flavoured crackers, rice cakes, and cheese puffs.

• Fast Food Items: Burgers, fries, chicken nuggets are typically high in salt.

• Salted Fish: Including anchovies, sardines, and smoked salmon.

• Sauces and Gravies: Pre-made or packet sauces and gravies can have a lot of added salt.

• Seasoning Mixes and Stock Cubes: Often used to enhance flavour but can be very high in sodium.

• Salted Butter and Margarine

Low-fibre diets 

Fibre is essential for a healthy gut as it feeds beneficial bacteria and promotes regular bowel movements. Diets low in fibre can lead to constipation and a decrease in beneficial gut bacteria, contributing to various digestive disorders.

To increase fibre, try to focus on eating foods like:

• Whole grains

• Lentils

• Onions

• Cabbage

• Chickpeas

• Wholemeal Bread

• Nuts

• Broccoli

• Apples

• Sweet Potatoes

• Raspberries

• Chia Seeds

Read more about the best foods for gut health.

Dairy products 

For individuals with lactose intolerance, dairy can cause symptoms such as bloating, gas and diarrhoea. Even for those without intolerance, high-fat dairy products can be hard to digest and may contribute to an imbalance in gut bacteria.

Gluten 

For those with gluten sensitivity or coeliac disease, gluten can cause significant damage to the gut lining, leading to nutrient malabsorption and an altered gut flora. 

Changing bad eating habits

Changing bad eating habits and transitioning towards a diet that nurtures the gut is a journey that requires commitment, awareness, and a gradual approach. Here’s how you can embark on a path to healthier eating habits for a happier gut.

Understanding your eating habits

The first step in altering your diet is to understand your current eating habits. Keep a food diary for a week, noting everything you consume, including snacks and drinks. This will help you identify patterns and foods that might not be beneficial for your gut health like those listed above.

Gradual changes

Abrupt dietary changes can be overwhelming and unsustainable. Start by making small adjustments. For instance, if you're used to having a biscuit with your tea, consider swapping it for a piece of fruit or a handful of nuts. Gradually incorporate more whole foods into your diet, such as fruits, vegetables, legumes, and whole grains, which are rich in fibre and essential nutrients that support gut health.

Focus on fibre

Fibre plays a crucial role in gut health by promoting healthy bowel movements and feeding the beneficial bacteria in your gut. Aim to include a variety of high-fibre foods in your diet, such as lentils, chickpeas, wholemeal bread, oats, and a range of fruits and vegetables. Not only does this support digestion, but it also helps you feel fuller for longer, reducing the temptation to snack on less healthy options.

Probiotics and prebiotics

Incorporate fermented foods rich in probiotics, like yoghurt, kefir, sauerkraut and kimchi, which introduce beneficial bacteria to your gut. Prebiotic foods, such as onions, garlic, and green bananas, feed the good bacteria and help them flourish. Together, these support a balanced gut microbiome, essential for good digestion and overall health.

Mindful eating

Pay attention to how you eat, not just what you eat. Eating mindfully, by chewing slowly and enjoying each bite, can aid digestion and prevent overeating. Try to make mealtimes calm and focused, free from distractions like television or smartphones. This can help reduce thoughtless, automatic snacking.

Hydration

Staying adequately hydrated is essential for gut health. Water aids digestion and helps maintain the balance of good bacteria in the gut. Aim for at least 8 glasses of water a day, and consider herbal teas as a gut-friendly alternative to caffeinated beverages.

Seek professional advice

If you're struggling to change your eating habits or if you have specific dietary needs or health concerns, consulting a healthcare professional or a registered dietitian can provide personalised guidance.

Moving forward

A diet high in the foods listed here can lead to a disruption in gut health, affecting not just digestion but overall wellbeing.

Transforming bad eating habits into ones that favour gut health is a gradual process that involves mindful choices, patience, and consistency. By adopting a diet rich in whole, fibre-rich foods, and incorporating probiotics and prebiotics, you can support your gut health and overall wellbeing. Remember, every small change contributes to a larger impact on your health.

Now read more about the best foods for gut health!

Or read our review of Symprove, the popular, science-based probiotic, to give your gut health a kick start and a helping hand.

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