Our gut microbiomes contribute to our overall health, and a healthy gut can aid in everything from weight loss to preventing chronic diseases. You (probably) already know that diet is largely responsible for how efficiently the gut functions, and eating things like processed foods or sugary sodas will make it lose steam over time. But there's a lot we're still learning about the microbiome—what keeps it healthy, and what could accidentally be causing it damage.
So we tapped gut health expert, Dr. William Bulsiewicz, a respected GI doctor at Lowcountry Gastroenterology in Charleston, SC and the mind behind The Gut Health MD, to find out what sneaky sources could be messing with your microbiome. Here are the six things he says to watch out for.
Even though calories from sugar are associated with weight gain, think twice before picking up that pink packet of sugar (or chugging that diet soda.) Though artificial sweeteners have no calories, Bulsiewicz says that anything we put into our mouths—caloric or not—has an effect on our gut microbiome, and could alter the digestive process in a negative way.
"While [artificial sweeteners] may have zero calories, you'll find that your ability to tolerate sugar in future meals will be affected because your gut microbiome has a tremendous impact on how you digest your food." Translation? Consuming zero-calorie sweeteners on a regular basis could eventually make it difficult for our bodies to process sugar and lower our glucose tolerance (a trait usually only found in people with diabetes.)
Antibiotics may be necessary to get rid of a pesky sinus infection, but they're not doing your gut any favors. In fact, Dr. Bulsiewicz says just a few days on antibiotics can cause damage to your gut microbiome. "Certain antibiotics can wipe out 35 percent of your gut bacteria—including a lot of good, healthy bacteria—and that damage can last for years."
While that may not sound like a big deal (after all, we have trillions of bacteria in our gut, right?), Bulsiewicz says, "If you have a team full of bacteria, but you wipe out a third of them, they're not going to work as they should."
But that doesn't mean you should swear off modern medicine. If you have to go on antibiotics, ask your doc to recommend a probiotic to pair with it. One study showed that coupling a round of antibiotics with a Lactobacillus probiotic helped drastically reduce diarrhea and abdominal pain. Plus, reintroducing that good bacteria will help ease the damage to your gut microbiome.
Okay, hear us out. We're big fans of a high-fiber diet—especially since eating more of the stuff leads to stable blood sugar and less weight gain—but there may be a compelling reason to ease into those fruits and veggies.
Dr. Bulsiewicz says, "97% of Americans aren't getting enough fiber, and it's an absolutely essential nutrient. But if you have too much of it at once, it can hurt."
He gives the relatable example of working out—if you haven't been working out your chest, but then go to the gym and try to bench press 300 pounds, you're going to hurt yourself. You have to build up that strength over time. That's why eating a ton of fibrous, cruciferous veggies—like a raw kale salad—can make you feel gassy or bloated.
"Some of the healthiest food can cause gas, bloating, abdominal discomfort in people with underlying damage to their gut microbiome," says Dr. Bulsiewicz. Gut damage can occur with certain medical conditions (rule those out with your doc), regular antibiotic use, or eating a poor diet.
If you feel GI distress after eating super-fibrous foods, take a break from raw veggies. Bulsiewicz recommends starting out with steamed vegetables, veggie-based soups, or roasted vegetables to get your fiber fix without any of the unwanted side effects.
FODMAPs (Fermentable, Oligosaccharides, Disaccharides, Monosaccharides, And Polyols) are, in simpler terms, a list of short-chain carbs that aren't always digested well by the small intestine. People with GI issues are sometimes put on a Low-FODMAP Diet, which restricts foods like fruit, wheat, beans, cruciferous veggies, onions, garlic, and dairy.
If you're thinking those are foods that are part of a healthy diet, you're right. Dr. Bulsiewicz says, "FODMAPs are inherently healthy prebiotics, meaning they feed and nourish the good bacteria in your gut, but if you overdo them you could cause GI distress."
The FODMAP Diet is a temporary eating plan that should be prescribed by your physician. It's used to help identify which foods cause GI distress, and gradually reintroduce the ones that do not. If you don't have any unpleasant side effects, nosh away (in moderation.)
Saturated fat isn't considered as unhealthy as it used to be, though there are healthier oils to lean on in your diet and the American Heart Association still recommends limiting it for heart health. If you've recently hopped on the coconut oil bandwagon, however, you may want to rethink your oil choice for your gut health.
One study done in mice showed eating a diet high in saturated fat actually changed the gut microbiome, causing inflammation and an increased risk of developing colitis.
Dr. Bulsiewicz says, "There are healthy fats, but saturated fat isn't the one you want—you want omega fatty acids, which have a prebiotic effect on the gut." Omega fatty acids can be found in foods such as cold-water fish, eggs, and chia seeds.
A Low-Carb Diet
A ketogenic diet may be all the rage right now, but reducing carbs to almost zero zaps vital nutrients that are key to our gut health.
Dr. Bulsiewicz says, "We can all agree that refined, ultra-processed carbs are bad, but unrefined, unprocessed, complex carbs fuel a healthy gut microbiome. Fiber, which is a carb, fuels a healthy gut. When we cut carbs, we're cutting all of them. We can't pretend that we're cutting carbs and keeping an adequate amount of fiber."
Another compelling reason to skip the keto diet? A study published in Nature showed that eating a high-fat diet (ahem, keto)—even for just a few days—drastically altered the gut microbiome and increased the growth of microorganisms capable of triggering inflammatory bowel disease.