Worst Foods to Eat for Gut Health and Digestion
Some foods and drinks can promote gastrointestinal problems and damage beneficial gut bacteria. These are the top foods to avoid for a healthy gut.
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Why a healthy gut microbiome matters
A healthy gut is essential for overall health and wellness. Your gut helps regulate digestion, boosts immunity and even affects mental health.
Supporting a healthy gut microbiome has been associated with reduced risk for certain diseases, such as Alzheimer’s disease and other forms of dementia, cancer and metabolic diseases, like obesity. And eating gut-friendly foods can support a diverse and healthy gut microbiome.
Conversely, certain foods “negatively impact the microbiome due to their inflammatory properties, minimal fiber and effect on insulin,” says Dana Ellis Hunnes, a senior clinical dietitian at UCLA Medical Center and assistant professor at UCLA Fielding School of Public Health in Los Angeles.
Inflammatory foods — including ultra-processed snack foods, red meats and sugar-sweetened beverages — can cause imbalances in the gut microbiome that can lead to an increased risk of digestive disorders like irritable bowel syndrome and inflammation throughout the body. That inflammation can then elevate the risk for certain diseases, such as heart disease, or exacerbate inflammatory conditions, like asthma and diabetes.
An imbalance of the gut microbiome
Your gut microbiome must be balanced – diverse and populated with plenty of beneficial microbes – if you want to have a healthy gut. This imbalance in the gut, often referred to as dysbiosis, is associated with a wide range of health problems, including:
- Acid reflux.
- Acne, psoriasis and skin rashes.
- Anxiety.
- Chronic fatigue.
- Constipation.
- Cramps.
- Diarrhea.
- Digestive issues.
- Food intolerance (bloating, gas).
- Trouble urinating.
- Vaginal or rectal itching or infections.
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Why a healthy gut microbiome matters
A healthy gut is essential for overall health and wellness. Your gut helps regulate digestion, boosts immunity and even affects mental health.
Supporting a healthy gut microbiome has been associated with reduced risk for certain diseases, such as Alzheimer’s disease and other forms of dementia, cancer and metabolic diseases, like obesity. And eating gut-friendly foods can support a diverse and healthy gut microbiome.
Conversely, certain foods “negatively impact the microbiome due to their inflammatory properties, minimal fiber and effect on insulin,” says Dana Ellis Hunnes, a senior clinical dietitian at UCLA Medical Center and assistant professor at UCLA Fielding School of Public Health in Los Angeles.
Inflammatory foods — including ultra-processed snack foods, red meats and sugar-sweetened beverages — can cause imbalances in the gut microbiome that can lead to an increased risk of digestive disorders like irritable bowel syndrome and inflammation throughout the body. That inflammation can then elevate the risk for certain diseases, such as heart disease, or exacerbate inflammatory conditions, like asthma and diabetes.
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An imbalance of the gut microbiome
Your gut microbiome must be balanced – diverse and populated with plenty of beneficial microbes – if you want to have a healthy gut. This imbalance in the gut, often referred to as dysbiosis, is associated with a wide range of health problems, including:
- Acid reflux.
- Acne, psoriasis and skin rashes.
- Anxiety.
- Chronic fatigue.
- Constipation.
- Cramps.
- Diarrhea.
- Digestive issues.
- Food intolerance (bloating, gas).
- Trouble urinating.
- Vaginal or rectal itching or infections.
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Worst foods for gut health
Not all gut bacteria are beneficial. And some foods and drinks increase the growth of harmful gut bacteria. The following seven foods and beverages have been shown to potentially damage gut health.
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1. Sugary foods and drinks
Excess sugar is one of the worst offenders for gut health. A 2018 study in the journal Nutrients found that mice fed a diet high in excess sugar experienced an alteration in the makeup of their gut microbiome as well as increased gut permeability (also known as leaky gut) and increased inflammation. This in turn increased rates of fatty liver disease.
Sugary drinks, in particular, are bad for gut health, according to research published in 2019 in JAMA Internal Medicine. In the study, researchers found that consuming more than one sugar-sweetened soft drink per day was associated with greater mortality from digestive diseases than drinking fewer than one soft drink per month.
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2. Artificial sweeteners
If sugar is harmful to gut health, artificial sweeteners should help you avoid that problem, right? Not so fast. Artificial sweeteners are another of the biggest culprits in poor gut health.
An array of artificial sweeteners pass through the body undigested, which means they can negatively affect the microflora in your gut, says Lisa Jones, a registered dietitian based in Philadelphia.
Research published in 2021 in the International Journal of Molecular Sciences suggests that consuming artificial sweeteners aspartame, saccharin and sucralose may be associated with two harmful gut bacteria, E.coli and E. faecalis.
In addition, a 2018 study in the journal Molecules reports that the consumption of artificial sweeteners has been linked with myriad adverse effects, including a negative change in gut microbiome activity.
Common artificial sweeteners include:
- Stevia, available under various brand names, such as Splenda Stevia Sweetener and Truvia.
- Aspartame, brand name Equal.
- Sucralose, brand name Splenda.
- Saccharin, brand name Sweet’N Low and Necta Sweet.
- Acesulfame, or Ace-K, brand name Sunett.
What’s more, in July 2023, the World Health Organization issued a report that labeled the non-sugar sweetener aspartame as possibly carcinogenic to humans, which may give you another reason to opt for water instead of that diet soda.
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3. Alcoholic beverages
The federal government’s 2020-2025 Dietary Guidelines for Americans recommends moderate drinking for those who imbibe. That means two drinks or less a day for men and one drink or less daily for women. Drinking more alcohol than this amount can harm your gut microbiome, Jones says.
Research published in the journal Gut Microbes in 2020 suggests that drinking alcohol excessively is also associated with dysbiosis. As mentioned earlier, dysbiosis occurs when the bacteria in your gastrointestinal tract – including your intestines – become unbalanced.
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4. Fried foods
Saturated fat, a key feature of fried foods, is also hard on the gut, making these foods more difficult for your body to digest compared to fresh fruits and vegetables, Jones says.
“The oils that may be used to fry the food are rich in saturated and trans fats, which can bother your gut,” she explains.
Palm and coconut oils are typically used to fry food. Eating fried foods can lead to:
- Diarrhea.
- Gas.
- Stomach pain.
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5. Red meat
While they might be delicious off the grill on a hot summer day, fatty meats like burgers, sausage and hot dogs can all be problematic.
“Diets high in red meat and fats are especially bad for gut health,” says Kim Kulp, a registered dietitian nutritionist specializing in gut health and the owner of the Gut Health Connection in the San Francisco Bay Area. “When gut microbes feed on red meat, they release an enzyme that can lead to inflammation.”
These foods are also high in L-carnitine, a compound that can alter the gut microbiome and lead to the production of trimethylamine N-oxide, or TMAO, says Stacy Cavagnaro, a registered dietitian with Cleveland Clinic’s Center for Human Nutrition. High levels of TMAO increase your risk for heart attack or stroke.
“Diets high in red meat have also been linked to colon cancer and heart disease,” Kulp adds.
A 2019 study in the journal Gut, for instance, found that higher consumption of high-fat foods led to unfavorable changes in the gut microbiome that could elevate risk for chronic diseases. In addition, research published in 2020 in the journal Advances in Nutrition suggests that “when consumed at higher-than-recommended levels as part of a diet high in sugar or fat, beef has adverse consequences for the gut microbiota.”
According to Kulp, too much high-fat food can lower the number of good gut bacteria while increasing the bacteria that can damage intestinal lining and lead to inflammation.
Cleveland Clinic recommends eating no more than one to two servings of red meat weekly, or 6 ounces per week. People with heart disease or high cholesterol should limit their consumption to 3 ounces weekly.
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6. Salty foods
Salty foods can also be detrimental to gut health, notes Dr. Edward Salko, a family and emergency medicine specialist and the medical director of Personalabs, a direct-to-consumer lab testing and telehealth company based in Fort Myers, Florida.
“Salty foods cause bloating, fluid retention, headaches and high blood pressure,” he explains.
High-salt foods, he adds, can also disrupt protein digestion, which can alter how the gut microbiome functions.
In addition, a 2019 review in the American Journal of Physiology notes that high-sodium diets “promote local and systemic tissue inflammation and impair intestinal anatomy compared with low sodium intake in both human and animal studies.”
The gut dysbiosis that results from a high-sodium diet could contribute to the development of hypertension, the study suggests.
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7. Ultra-processed foods
Processed foods containing additives and salt are also on the foods-to-avoid list, Cavagnaro says.
“Eating processed foods that contain additives and salt can affect your gut microbiome negatively,” she points out.
Certain ultra-processed foods also contain excess sugar, which can be hard on the gut.
Highly processed foods include:
- Bacon, ham, pate and sausage.
- Canned vegetables.
- Cakes.
- Cookies.
- Processed lunch meats.
- Soft drinks.
Ultra-processed foods are also typically low in dietary fiber, which is an important micronutrient. Fiber is important for maintaining gut regularity and for feeding the beneficial bacteria in our gut.
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Moderation in all things
Lastly, Anastasia Gialouris, a registered dietitian in Brooklyn, says that while it’s best to avoid processed foods, she doesn’t want to “scare folks into thinking they can never eat a packaged cookie or french fry again if they want to support their gut health.”
Instead, she recommends consistently practicing healthy habits, with a little flexibility to eat the less healthy foods that bring joy and satisfaction. This balance can make you happier and healthier, she says.
Experts recommend steering clear of any diets, products or supplements advertised as detoxes, cleanses or quick fixes that can improve gut health. The focus should not be on an individual food but the overall eating pattern that a person follows.
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