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You can support your gut health in many ways: get enough sleep, drink enough water, manage your stress levels, take a probiotic… But the unfaltering, number-one, best way to support your gut health is to eat well, which means steering clear of foods that throw your microbiome off-kilter.
Here are 9 foods thought to damage or disrupt your gut microbiome.
No surprise here — it’s no secret that sugar isn’t friendly to your body. Table sugar may have the worst reputation, but sugar in any form (including natural sources) is potentially harmful. Research reports that sugar negatively affects digestion, induces constipation, and results in poor gut function.
The microbes in your gut get their food from the food that you eat, and sugar just so happens to feed the bad guys. The more sugar you consume, the more the bad bacteria can grow, until they outnumber the good bacteria.
2. Artificial Sweeteners
So if you can’t have sugar, where do you turn? Many people look to artificial sweeteners and sugar alcohols, which offer low- or no-calorie alternatives to sugar. But while these may help keep your waistline in check, they can lead to diarrhea, bloating, constipation, cramping, or other gut-related symptoms.
These symptoms could be due to the negative effects of artificial sweeteners, which include changes to your microbial composition, decreased insulin sensitivity, and higher rates of metabolic disease.
Dr. Mahmoud Ghannoum, leading microbiome researcher and known as Dr. Microbiome, himself avoids artificial sweeteners because of their strong associations with gut imbalance!
3. Red meat
Eating an occasional steak or burger won’t devastate your gut microbiome, but you should make it a point to know where your beef comes from.
Humans have been eating red meat for centuries, and our digestive systems are equipped to handle it. However, the meat in our markets today is not akin to the meat our primal ancestors ate.
Today, some meat products are highly processed: they are smoked, cured, and treated with various chemicals, including nitrates and preservatives. This is on top of the fact that many meat products are made from animals that were raised in a factory, fed grain-based feed, and received antibiotics and hormones.
You don’t need to cut out red meat completely, as it’s a great source of iron, B vitamins, and protein. Just look for organic, grass-fed meat whenever possible. Studies seem to agree that processed red meat is harmful, but unprocessed red meat can be healthy in moderate amounts.
4. Deli meats
Another protein with potential to harm your microbiome is deli meat. Deli meats are incredibly convenient, however, like red meat, deli meat often comes from animals that were given antibiotics and hormones before slaughter.
These factors combined result in a product that’s not ideal for gut health: hormones and antibiotics can shift your microbiome in the wrong direction.
5. Farmed fish
Just like conventionally farmed red meat, conventionally farmed fish are often kept in subpar conditions and fed a subpar diet, which transfers over to our own health and well-being.
To compensate for the poor diet they feed their fish, fish farmers sometimes give their fish antibiotics and growth hormones to make them seem more suitable for human consumption.
On top of that, some types of fish contain high amounts of mercury, which can be dangerous and is associated with a reduction in microbiome diversity.
Fish provides a great deal of nutrients, including omega-3s that are critical to overall health, so we don’t want you to stop eating fish entirely. Just aim to purchase wild-caught fish and species that contain less mercury, such as flounder, herring, salmon, whitefish, mackerel, or small fish like sardines.
6. White bread
“White bread” really means any processed food that uses refined white flour. This means snacks like pretzels, crackers, and yes, even “healthy” ones like granola bars.
Refined white flour feeds unfriendly bacteria in your gut just like sugar does, and leads to many of the same symptoms: bloating, cramps, and poor digestive function.
Conflicting evidence suggests that drinking whole milk doesn’t affect the richness or diversity of your gut. Whether or not to avoid dairy comes down to the individual — Dr. Microbiome notes that eating too little dairy could be just as harmful as eating too much, for some people. Consider trying milk alternatives like oat, soy or almond milk. If you really want a dairy product, purchase low-fat versions!
Gluten is another food that’s very finicky from person to person. A protein found in many grains, such as wheat and barley, gluten can cause abdominal pain, bloating, and fatigue even in individuals who don’t have Celiac disease. “Gluten sensitivity” is the term for that. Research also suggests that going gluten-free lowers insulin resistance and can halt weight gain.
Before you say, “but what about red wine?!”, understand that we know the benefits of red wine. We’re talking about chronic consumption of alcohol (any kind, including red wine), which is associated with dysbiosis, or an imbalanced gut.
That said, research proves that some kinds of alcohol do more harm than others. In one study, subjects who drank gin exhibited a decrease in beneficial gut microbes, while participants who drank red wine exhibited an increased number of healthy bacteria. The red wine also decreased some strains of harmful gut bacteria. Dr. Microbiome suggests limiting your consumption of alcohol and opting for other beverages that promote optimal gut health.
Create your own version of a gut-healthy diet
Remember not everyone needs to avoid every food on this list. Certain “healthy” foods don’t work for everyone, and certain “unhealthy” foods sit just fine with some people.
For example, you may find that your gut health (and thus your overall health) thrives when you eat a diet high in whole grains, but perhaps eggs don’t agree with you. Someone else may notice they get an upset stomach every time they eat gluten, but tolerate dairy extremely well.
These are classic examples of why it’s helpful to get your microbiome sequenced or try an elimination diet — without knowing what’s going on in your gut or what it’s sensitive to, it’s impossible to build an ideal gut-friendly diet for yourself.
Editor’s note: This post has been updated for relevancy. Its first publish date was September 1, 2019.