Why your gut's not a fan: They contain FODMAPs, or fermentable oligo-di-monosaccharides and polyols—carbohydrates that some people don't digest well in large amounts (garlic and onion are high in particular ones called fructans). While experts don't know for sure how many people have issues with FODMAPs, research suggests that people with irritable bowel syndrome (which affects 10 to 15 percent of Americans) are prime targets. Bacteria in our large intestine and colon start to ferment the FODMAPs, causing gas, bloating and cramping, says Neha Shah, MPH, RD, a clinical dietitian for Stanford Health Care.
How to fix it: If you can't imagine cooking without garlic and onions but your digestive tract is begging you to stop, try Shah's trick of simmering them in olive oil to infuse it with their flavors (the fructans don't leach out into the oil) and then cooking with the oil instead.
Why your gut's not a fan: The fat found in treats like ice cream and animal products like cheeseburgers can increase the growth of potentially harmful gut bacteria. When researchers put mice on a high-milk-fat diet for a study in Nature, it triggered overgrowths ofbilophila wadsworthia—a type of bacteria found in all of our stomachs but normally kept in check. The result? Severe inflammation in the colon. It's not because the bacteria are feeding on the milk fat, though—our bodies produce bile in order to digest certain fats, and "the bacteria is using that bile as a fuel source," says study author Suzanne Devkota, MD, a research fellow at Harvard's Joslin Diabetes Center. "It's like adding oxygen to a fire." Another study in Nature found that a high-saturated-fat diet in humans (bacon and eggs for breakfast, ribs and brisket for lunch, salami, prosciutto and cheese for dinner, plus pork rinds for snacks), led to increases in that same bile-loving bacteria.
How to fix it: Limiting your consumption of saturated fats can help keep this bacteria at normal levels. The American Heart Association recommends that healthy individuals get no more than 7 percent of their daily calories from saturated fat (roughly 16 grams of saturated fat on a 2,000-calorie-a-day diet), while people with high cholesterol should cap it at 5 to 6 percent of their daily calories (11 to 13 grams). Just in case you need another reason to adopt a more plant-based diet, consider that subjects on the meat-bonanza meal plan also reported less regularity in their bowel movements while following it.
Why your gut's not a fan: Artificial sweeteners contain FODMAPs, and that means they're osmotic, pulling water into your intestinal tract and potentially causing diarrhea. And because artificial sweeteners (look for ingredients that end in an "ol", like sorbitol or mannitol) are calorie-free, our bodies don't recognize them as nutrients and don't digest them, says Lisa Ganjhu, MD, a gastroenterologist at NYU Langone Medical Center. That leads to gas and bloating.
How to fix it: If you find that your stomach doesn't feel so great after you get your morning caffeine-and-fake-sugar fix, use small amounts of actual sugar instead.
Why your gut's not a fan: FODMAPs are at it again—this time, it's the galactans in your legumes. If you think you may be sensitive to them (or any other FODMAPs on this list), bring it up with your doctor before altering your diet, as your digestive distress could actually be caused by a more serious underlying issue like celiac disease or inflammatory bowel disease, says Shah. If your doctor rules those out, ask about going on a FODMAP elimination diet, where all FODMAPs are removed for 6 weeks then slowly reintroduced to pinpoint which ones are causing your problems. You can find more information about FODMAPS and a low FODMAP diet here.
How to fix it: The galactans in beans and lentils can be at least partially removed by soaking them uncooked in water overnight then cooking them with a fresh batch of water, because the galactans get pulled out during the initial soak, says Shah. "My patients have far less gas and bloating when they prepare beans and lentils this way."
Why your gut's not a fan: Lactose falls in the FODMAP camp, so any cheese could pose problems for sensitive stomachs. But high lactose cheeses like cottage and ricotta are the most likely to cause digestive issues. These particular cheeses tend to undergo short straining processes, and less lactose gets removed as a result.
How to fix it: If you find that cottage and ricotta don't sit well with you, try snacking on low-lactose options like brie, feta and mozzarella. Hard cheeses like cheddar, parmesan and Swiss are also fair game, as they're low in lactose too. Just remember that when it comes to sensitivity to cheese (or any food that's high in FODMAPs), the amount that you're eating makes a difference, so try cutting back on your portion sizes before cutting out a food entirely.
Why your gut's not a fan: True, it's not food, but alcohol can be bad for your gut too. Just one episode of binge drinking (for women, that means consuming 4 or 5 drinks within two hours) can cause bacteria to leak out of your gut into your bloodstream, found a 2014 study in PLOS One. The effect was more pronounced in women than in men, and it could lead to inflammation throughout the body. "It's not going to kill anyone immediately, but over time, this low-grade inflammation can predispose you to chronic diseases," says study author Gyongyi Szabo, MD, PhD, a professor of medicine at the University of Massachusetts Medical School.
How to fix it: Moderate drinking, meaning 1 drink per day for women, according to the Dietary Guidelines for Americans, is your best bet for avoiding the potential negative effects of alcohol.
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