The kinds that just make you poop, STAT:
There’s also the rarer insoluble fiber supplements, which don’t dissolve, form a gel, or get fermented, like calcium polycarbophil (FiberCon) and wheat bran. These mostly have a laxative effect, prompting your gut to release more liquid and bulking up poop to move it through you. Same goes for methylcellulose (Citrucel), which is technically a soluble fiber but doesn’t form a gel nor get fermented; it just adds volume to keep poop chugging along.
The combination fiber with a bunch of benefits for both your heart and gut:
And then there’s psyllium (Metamucil, Konsyl), which is in a category of its own: It’s mainly soluble and gel-forming, so it can lower cholesterol and control blood sugar, but it also contains some insoluble fiber and does not typically get fermented. This combination creates a unique poop-normalizing effect, meaning it can help with both constipation and diarrhea. Like insoluble fibers, it doesn’t get broken down in your gut and it draws water into your stool, creating easier-to-pass poops—but its tendency to clump up into a gel can also firm liquid-y poops in diarrhea and help reduce frequency and urgency, Amy Bragagnini, MS, RD, clinical oncology dietitian at Trinity Health Lacks Cancer Center, in Grand Rapids, Michigan, and spokesperson for the Academy of Nutrition and Dietetics, tells SELF. So basically, it’s a catchall fiber supplement—the one that Anish A. Sheth, MD, a gastroenterologist at Penn Medicine and chief of gastroenterology at Princeton Medical Center, tells SELF he recommends regularly to his patients above all other types.
Whichever kind you choose, be sure to scan the ingredients list for what’s included beyond the fiber. You’ll want to steer clear of supplements with a lot of artificial sweeteners or added sugar (common in gummy and wafer versions), Bragagnini says, as both could be counterproductive for your gut. And also note that certain options may contain gluten (for instance, ones with wheat dextrin or wheat bran), so keep an eye out if you have Celiac or are gluten-sensitive.
You might need to avoid fiber supplements if you have certain health conditions or are on medication.
Fiber is tricky territory for some people, including folks with a functional GI condition like irritable bowel syndrome (IBS). Fermentable types of fiber (as well as high-fiber foods that get similarly broken down, for that matter) can worsen IBS symptoms, Dr. Sheth says. That’s because your gut bugs pump out gas as a byproduct of fermentation, he notes, which may trigger bloating and distention (a puffed-out belly). Research suggests our microbes really chow down on inulin, so that one may especially cause gas and discomfort in sensitive folks.
On the flip side, supplementing with psyllium has been shown to improve IBS symptoms, by way of its poop-regulating effect. And in people whose IBS manifests as constipation (IBS-C), insoluble fibers like wheat bran could help get things going and alleviate symptoms. All to say, if you have IBS, it’s essential to chat with your doc to figure out whether you should take a fiber supplement, and if so, which type.
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