5 Simple Tips To Starve Bad Gut Bacteria (From A Nutritionist)


Do you need to reduce the population of unfavorable bacteria in your gastrointestinal (GI) tract?

If you think you do, you probably do! 

If you aren’t sure, read my article “How to Identify Symptoms of Yeast Overgrowth in the Gut.”

You’ve probably heard that gut health is important for optimized health…

But, did you know that your gut health is largely determined by the balance of good and bad bacteria in your digestive tract?

And that an imbalance of these bacteria is related to almost every health problem and disease.

Gut bacteria influence:

  • Digestion
  • Inflammation
  • Metabolism
  • Immunity
  • Cognition 

That’s a big deal, right?

Well, don’t worry.

In this comprehensive guide, I’m going to tell you exactly how to starve and reduce bad gut bacteria and improve overall gut health.

As a ISSA certified nutritionist, I’ve spent countless hours reading studies and breaking down the science surrounding gut health and enhancing the gut microbiome.

Today, I’m going to share with you the proven strategies that I use with my clients to help them optimize their gut health.

By the end of this article, you will be able to:

  • Understand gut health and what the gut needs to be healthy
  • Identify the good and bad bacteria in the gut and how they affect health
  • Restore the balance and diversity of the gut microbiome
  • Prevent and treat dysbiosis (the condition of having too much bad bacteria in the gut)


Let’s dive right in.

Understanding gut health

Your gut health is more than just how your stomach feels or how well you digest your food. 

Your gut health is dependent on the trillions of microorganisms that live in your gastrointestinal tract, which includes your mouth, your esophagus, your stomach, your small intestine, your large intestine, and your anus. 

The gut is made up of your mouth, your esophagus, your stomach, your small intestine, your large intestine, and your anus
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All these microorganisms are collectively known as the gut microbiome or gut flora.

What makes up the gut microbiome

The gut microbiome is composed of bacteria, fungi, viruses, and other microbes that have various roles and functions in the body. 

Some of these microbes are beneficial; some are harmful, and some are neutral. 

The balance and diversity of these microbes can affect your health in many ways. 

To evaluate your gut health, you need to consider the quantity, quality, and diversity of your gut microbiome.

You also need to consider all the factors that can influence your gut microbiome, including diet, lifestyle, environment, genetics, medications, infections, and diseases.

The battle between good and bad bacteria

One of the key aspects of gut health is the balance between good and bad bacteria in the gut. 

The good bacteria

Good bacteria are bacteria that have beneficial effects on health and well-being. They serve many functions, including:

  • Digesting foods and absorbing nutrients
  • Producing vitamins, hormones, and neurotransmitters
  • Regulating the immune system and inflammation
  • Protecting from pathogens and toxins
  • Modulating mood, cognition, and behavior

Some examples of good bacteria species are Lactobacillus, Bifidobacterium, Akkermansia, and Faecalibacterium.

The bad bacteria

Bad bacteria are bacteria that have harmful effects on health and well-being. 

They can cause a host of health problems, including:

  • Digestive issues like bloating, gas, diarrhea, and constipation
  • Inflammatory conditions like irritable bowel syndrome, irritable bowel disease, ulcers, and allergies
  • Metabolic disorders like obesity, diabetes, and fatty liver disease
  • Immune dysfunctions like infections, autoimmune diseases, and cancer
  • Neurological problems like depression, anxiety, and cognitive decline

Some examples of bad bacteria are Escherichia coli (E. coli), Salmonella, Helicobacter pylori (H. pylori), and Clostridium difficile (C. diff).

good and bad gut bacteria
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Striking a healthy balance

The battle between good and bad bacteria is a constant struggle for survival and dominance in the gut. 

Good bacteria and bad bacteria compete for space and resources. 

Good bacteria prevent the overgrowth of bad bacteria by producing substances that inhibit or kill bad bacteria, including acids, hydrogen peroxide, bacteriocins, and antimicrobial peptides.

Bad bacteria try to overgrow by multiplying rapidly, producing toxins and enzymes that damage the gut lining and good bacteria, and invade the bloodstream and organs. 

What determines the winner of the gut battle

The winner of this battle depends on several factors, including:

  • The number and diversity of good and bad bacteria
  • The availability of nutrients and oxygen
  • The pH level and temperature of the gut
  • The presence of other microbes or pathogens
  • The condition of the host’s immune system
  • Lifestyle factors including diet, sleep, exercise, stress, medications, and infections

What is dysbiosis and why does it occur?

Dysbiosis is a condition where the proportions of good and bad bacteria in the gut are imbalanced, which is associated with a wide range of diseases, including neurodegenerative diseases like Parkinsons Disease, cardiovascular disease, diabetes, and more (see diagram below).

Dysbiosis can occur in various ways, including:

  • A reduced number of good bacteria 
  • An increased number of bad bacteria 
  • A decrease in bacterial diversity
causes of gut dysbiosis
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Factors that cause dysbiosis

There are several ways that this can occur. Some common causes of gut dysbiosis are:

  • A poor diet: can starve good bacteria while feeding pathogenic bacteria
  • Antibiotics: can kill both good and bad bacteria 
  • Stress: can weaken the immune system and alter gut motility
  • Infections: can introduce harmful microbes or toxins into the gut
  • Diseases: can damage the gut lining or impair digestion

Are you ready to explore the five science-backed, practically full proof ways to ensure that you always have more good bacteria than bad bacteria in your digestive system?

 Let’s get into it!

Tip #1: Eat foods that fuel good bacteria

One of the best ways to starve bad gut bacteria is to feed good bacteria with the right foods. 


Good bacteria eat and proliferate when they have fiber-rich foods. They particularly thrive with vegetables and fruits, which help them produce short-chain fatty acids (SCFAs). 

SCFAs are beneficial compounds that nourish the gut lining, reduce inflammation, and lower blood sugar and cholesterol levels.

Some examples of fiber-rich vegetables and fruits include broccoli, spinach, carrots, apples, bananas, and berries.

Fermented foods

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Fermented foods are great sources of good bacteria. Fermented foods are foods that have been partially predigested by beneficial microbes through a process called fermentation. 

Fermentation enhances the flavor, texture, and nutritional value of foods. The fermentation process creates probiotics, which are live bacteria that can colonize the gut and improve digestion and immunity.

Some examples of fermented foods are yogurt, kefir, sauerkraut, kimchi, miso, and kombucha.

Essentials fats

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Essential fats are fats that the body can’t produce. They must be obtained from foods. 

Essential fats include omega-3 and omega-6 fatty acids, which have anti-inflammatory properties that support brain and heart health. 

Omega-3 fatty acids can also modulate the gut microbiome by increasing the diversity and abundance of good bacteria. 

Some examples of omega-3 and omega-6 rich foods are flax seeds, chia seeds, walnuts, fish oils, and fatty fish such as salmon, mackerels, and sardines.


Polyphenols are natural compounds found in plants that have antioxidants and anti-inflammatory effects. 

Polyphenols can influence the gut microbiome by stimulating the growth of good bacteria and inhibiting the growth of bad bacteria. 

Some examples of polyphenol-rich foods are green tea, red wine, dark chocolate, coffee, blueberries, grapes, and turmeric.

Low carbohydrate diets and gut health

While there are mixed studies on low carbohydrate diets impact gut health, there is a ton of promising research that a ketogenic style diet can positively impact gut health. I wrote more about it here in my article The Science Behind Keto & Gut Health.”

Tip 2: Avoid artificial sweeteners and processed foods that feed bad bacteria

While some foods can nourish good bacteria, others can fuel bad bacteria. Artificial sweeteners and processed foods are among the worst offenders. 

Artificial sweeteners

Artificial sweeteners are synthetic substances that mimic the taste of sugar without providing any calories or nutrients. 

They may seem like good alternatives to sugar for weight loss or diabetes management, but they actually harm gut health by altering the composition of gut bacteria and by increasing the risk of glucose intolerance and diabetes.

Artificial sweeteners impact the gut microbiome

Some examples of artificial sweeteners are aspartame, saccharin, and sucralose. They are typically found in low calorie or low sugar processed foods. 

Processed foods

Processed foods can also increase the growth of bad bacteria and yeast in the gut. 

These foods are usually high in processed sugar and calories but low in fiber and nutrients. They cause spikes in blood sugar levels and trigger inflammation in the body. 

They also feed harmful microbe species including Candida albicans, which can cause infections and inflammation in the mouth, throat, and genitals. 

Examples of these foods include soda, candy, cookies, cakes, pastries, ice cream, chips, crackers, and white bread.

Instead of artificial sweeteners, opt for natural sweeteners, such as honey, maple syrup, or stevia. 

However, you should still use them sparingly and in moderation. 

It is also best to choose whole foods that are minimally processed and that contain more fiber and nutrients. 

For example, eat whole grains, such as brown rice, quinoa, or oats, instead of refined grains, such as white rice, white flour, or white pasta.

Tip 3: Optimize your sleep routine, exercise more, and manage your stress levels to support gut health

Your gut health is not only affected by what you eat but also by your lifestyle. 

Your sleep routine, exercise habits, and stress levels can all impact your gut bacteria. 

To starve bad gut bacteria, you should consider the following lifestyle tips:


Create an effective sleep routine. 

Sleeping in alignment with your body’s natural circadian rhythm is important for deep sleep and a healthy gut. Your gut bacteria also have a circadian rhythm that fluctuates based on your eating and sleep schedules.

If you disrupt these cycles, you can cause imbalances in your gut microbiome and increase your risk of obesity, diabetes, and inflammation. 

To improve your sleep quality, avoid caffeine, alcohol, and screens several hours before bedtime. Try to go to bed and wake up at the same time every day. 

Aim for at least seven to eight hours of sleep per night.


Exercise more. 

Physical activity can benefit gut health by increasing the diversity and abundance of good bacteria in the gut. 

Exercise can also reduce inflammation, improve blood flow, and enhance mood and energy levels. 

Aim for at least 150 minutes of moderate exercise per week. 

Choose an activity that you enjoy and that suits your fitness level.

Manage Stress

Stress can harm gut health by altering the balance of gut bacteria and weakening the immune system. 

Stress slows digestion which can cause digestive problems. 

To cope with stress practice mindfulness, meditation, or breathing exercises. 

Find healthy ways to relax and unwind, such as reading a book, listening to music, or taking a bath.

Tip 4: Take probiotic supplements to increase good bacteria and prebiotic supplements to feed them

Another way to starve bad gut bacteria and improve gut health is to take supplements that support good bacteria

Probiotic supplements are supplements that contain live bacteria that can colonize in your gut and improve digestion and immunity. 

Prebiotic supplements are supplements that contain fiber that feed good bacteria and stimulate their growth.

Choosing the right probiotic supplement

When choosing a probiotic supplement, look for one that contains multiple strains of bacteria, preferably from the Lactobacillus and Bifidobacterium genera. 

These are the most common and well-studied types of good bacteria in the human gut. 

Also, check the label for the number of colony-forming units (CFUs), which indicates how many live bacteria are present in each dose. 

Aim for at least 10 billion CFUs per day.

You can also get probiotics from the food sources that we discussed earlier like yogurt, kefir, sauerkraut, kimchi, miso, and kombucha. Food sources typically contain less CFUs than supplements. 

How to pick the right prebiotic supplement

When choosing a prebiotic supplement, look for one that contains inulin, fructooligosaccharides (FOS), galactooligosaccharides (GOS), or resistant starch. 

These are types of fiber that feed good bacteria and help them grow. 

You can also get prebiotics from food sources, such as garlic, onion, asparagus, banana, oats, and barley.

How to take prebiotic and probiotic supplements

You can take probiotic and prebiotic supplements together or separately, depending on your preference, tolerance, and meals. 

You should take them with or after meals to ensure their survival and delivery to the gut. 

You may experience some mild side effects, including gas, bloating, or diarrhea when starting probiotic or prebiotic supplements. 

These are usually temporary and indicate that your gut bacteria are changing and adjusting. 

However, if these symptoms persist or worsen, you should lower the dose and/or stop taking the supplements and consult with your doctor.

Tip 5: Consider antimicrobial or antibiotic therapy to kill bad gut bacteria (use sparingly)

Antimicrobial or antibiotic therapy is treatment that involves using substances that kill or inhibit the growth of microbes, such as bacteria, viruses, fungi, or parasites. 

Antimicrobial or antibiotic therapy can help in cases of severe dysbiosis or infection, when bad gut bacteria have overgrown and caused serious symptoms or complications.

That being said, antimicrobial or antibiotic therapy should only be used as a last resort when other methods have failed or when you have a serious infection. 

Antimicrobials and antibiotics kill both good and bad bacteria, which can further disrupt the gut balance and cause side effects including diarrhea, nausea, or yeast infections. 

Some examples of natural antimicrobial or antibiotic agents that can be used to treat bad gut bacteria are:


Berberine supplement
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Berberine is a natural compound found in plants such as goldenseal, barberry, and oregon grape. 

Berberine has antibacterial, antifungal, and anti-inflammatory properties.

It can help reduce the growth of bad bacteria such as E. coli, Salmonella, and H. pylori.

 It can also lower blood sugar and cholesterol levels.

Oregano oil

Oregano oil is an essential oil extracted from the oregano plant. 

Oregano oil has antimicrobial, antifungal, and antioxidant properties.

 It can help kill bad bacteria such as Candida, E. coli, and Staphylococcus

It can also improve digestion and immunity. 


Garlic is a common culinary herb.

Garlis has potent antimicrobial, antifungal, and anti-inflammatory properties. 

Garlic can help fight bad bacteria such as E. coli, Salmonella, and H. pylori.

 It can also lower blood pressure and cholesterol levels.

Colloidal silver

Colloidal silver is a suspension of tiny silver particles in water.

Colloidal silver has antibacterial, antiviral, and antifungal properties

It can help eliminate bad bacteria such as E. coli, Salmonella, and MRSA.

It can also boost immunity and promote wound healing. 


Antibiotics are usually reserved for extreme cases and serious infections that are caused by specific bacteria and that do not respond to other treatments. 

Antibiotics can be effective in treating infections including urinary tract infections, pneumonia, and sepsis. 

Antibiotics can cause side effects including diarrhea, nausea, and yeast infections. 

Antibiotics are powerful and destroy both good and bad bacteria. They can also contribute to antibiotic resistance, which is a global health threat.

If you must take an antibiotic, take the smallest effective dose and take probiotics and prebiotics during the treatment to help repopulate the good bacteria. 

Wrapping it up

I hope you enjoyed this article on how to starve bad gut bacteria and improve gut health. By following these five evidence-based tips, you can starve bad gut bacteria and enhance your gut health and ultimately your overall health. 

Which one will you try first?

If you want to know if you are making progress in your battle of bad versus good bacteria, check out my article “6 Science-Backed Signs Your Leaky Gut is Healing”. 

If you have any questions or feedback, feel free to contact me anytime.


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Nolwen Cameron

Nolwen Cameron has had a lifelong passion for exercise and nutrition. She loves to educate and coach people to help them feel and look healthy inside and outside. She is an ISSA Certified Specialist in Fitness Nutrition and NASM Certified Personal Trainer.

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