December 9, 2023
Best Fiber Supplements for Constipation, Diarrhea, and Discomfort
best fiber supplement

If you don’t eat enough fruits and vegetables, your poop (or lack thereof) probably shows it. Filling your plate with produce means you’re also filling your belly with fiber—a type of carbohydrate essential to healthy digestion (and yes, good bowel movements). Everyone knows it can be tricky to get your greens in, though, which is when a fiber supplement may come in handy. But there are different types that have slightly different functions.

“Though most Americans don’t eat enough dietary fiber, it’s actually found in many foods. Fruits, vegetables, whole grains, and legumes are all natural sources,” explains Heather Mangieri, R.D.N., a sports and wellness dietitian in Pittsburgh, Pennsylvania. In fact, research suggests that 95% of American adults consume less than the daily 21 to 38 grams recommended by the Institute of Medicine. Getting enough is crucial not only because it keeps you regular, but Samantha Cassetty, M.S., R.D., explains that a fiber-rich diet is associated with a more diverse microbiome, “which is a sign of a healthy gut.”

Types of fiber

The two types of fiber are insoluble fiber—which does not dissolve in water and promotes the movement of material through the digestive system, increasing stool bulk and supporting bowel regularity, explains Mangieri—and soluble fiberwhich does dissolve in water, often forming a thick gel that helps slow digestion and absorption of nutrients. “Including viscous soluble fibers with meals creates a greater feeling of fullness, which can help control food intake and support weight loss efforts,” Mangieri adds. She says soluble fiber is also known for its ability to lower cholesterol and help maintain blood glucose levels.

How we chose the best fiber supplements

We consulted Mangieri and Cassetty, and poured through research and customer reviews to narrow down the best fiber supplements.

Dietary supplements are products intended to supplement the diet. They are not medicines and are not intended to treat, diagnose, mitigate, prevent, or cure diseases. Be cautious about taking dietary supplements if you are pregnant or nursing. Also, be careful about giving supplements to a child, unless recommended by their healthcare provider.

Our top picks

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Best Fiber Supplement Overall

Psyllium Husk Powder

  • Organic
  • For Constipation and Diarrhea
  • Versatile Powder Form
  • Affordable
  • Users Say It Can Be Slow to Dissolve

Studies have shown that psyllium fiber supplements may help lower cholesterol and lead to better glucose control,” explains Cassetty. “This type of fiber may also help normalize your bowel habits. So, if you have constipation, it can help soften stool and make it easier to pass, and if you have diarrhea, it can help create firm stool.” She recommends this one because it’s so versatile and natural. Plus, it has great reviews with over 2,000 testimonials and a 4.5-star rating on Amazon.


Best Fiber Supplement Blend

Raw Organic Fiber Supplement

  • Organic
  • Contains Insoluble and Soluble Fibers
  • Users Say It Could Taste Better

This powder supplement contains a blend of natural soluble and insoluble fibers in the form of flax seeds, chia seeds, quinoa, and various bean sprouts. There are no added sugars, and the daily recommended one scoop is easily mixed in with a glass of water or breakfast cereal.

“I worked at a gastro doctor for several years and tried several products. Both over the counter fibers and prescription. I always come back to this product and have been using for years,” one Amazon reviewer writes.


Best Psyllium Seed Husk Fiber Supplement

Metamucil Smooth Texture Unflavored

  • Over 100 Servings
  • Unflavored

If you’re looking for a psyllium seed husk supplement, Cassetty says this bare-bones formula fits the bill. The drinkable powder supplement has over 21,000 Amazon reviews and maintains a 4.7-star rating. Users say daily consumption has helped with constipation, diarrhea, and maintaining bowel movement regularity. Just be sure to pick up the version with no added sweeteners, as the sugar-free formula contains aspartame.

“Metamucil has actually changed my life. I use 1 teaspoon every morning with 10 oz of water, and I’ve been regular since adding this to my routine,” one reviewer writes. “This is the first product that has consistently worked for me after years of struggling with chronic constipation.”


Best Prebiotic Fiber Supplement

Gentle Prebiotic Sunfiber Supplement

  • Helps With Gas and Bloating
  • Unflavored
  • Some Users Report Stomach Discomfort

“If you’re shopping for a prebiotic fiber supplement, Sunfiber is a branded ingredient that’s gentle on your GI system,” explains Cassetty. Sunfiber comes from guar fiber, also known as partially hydrolyzed guar gum (PHGG). Cassetty recommends Cavu’s formula, which is unflavored and prevents excess gas or bloating.


Best Fiber Supplement Gummies

Fruity Bites Daily Prebiotic Fiber Supplement Gummies

If you’re not interested in dissolving powder into your morning glass of water, we don’t blame you. These gummies are not only naturally tasty with no added sugar, but they are made of fructooligosaccharides, a plant-based soluble fiber and prebiotic for a gut healthy boost.

“These are the best tasting gummy fibers that I’ve had and I’ve tried quite a few,” one reviewer writes.


Best Methylcellulose Fiber Supplement

Citrucel Methylcellulose Fiber Caplets

These methylcellulose tablets are marketed for occasional constipation relief without the added side-effects of gas and cramping. Methylcellulose is a synthetic compound used as a thickener in the culinary world, but acts as a binding soluble fiber in your gut.

“I had IBS for years and Citrucel has been the only lasting cure for my symptoms,” one reviewer writes. “This was recommended to me by my gastro doctor and I’ve never gone back. I recommend this to everyone I know,” another adds.

How to choose and use the best fiber supplements

While picking up a fiber supplement may sound like the solution to your digestion woes, if used incorrectly, it can wreak havoc on your gut. That’s why Mangieri recommends, first and foremost, doing your best to get the fiber you need through food.

“However, people suffering from constipation, diarrhea, irritable bowel syndrome, or other medical conditions that are not able to get enough fiber from foods may benefit from a supplement,” she adds. Here are her other tips for trying one out:

Start slow: “It’s important to be mindful of how much added fiber you consume,” she says, adding that incremental introduction is crucial. “Increasing dietary fiber too quickly can lead to side effects like gas, bloating, and cramps.”

Talk to your doctor: Mangieri recommends discussing your plan to start a fiber supplement with your doctor or a registered dietician, who can offer professional guidance.

Check the label: Look for a product that comes from a reputable manufacturer. “The product should list the fiber source on the package and the company should be able to answer your questions,” Mangieri says.

What’s in a fiber supplement?

Common ingredients you’ll see on labels are natural soluble fibers psyllium seed husk and inulin (which is also a prebiotic), as well as synthetic soluble fibers like methylcellulose (a manufactured version of cellulose). Flax seed and wheat bran are insoluble fibers that may also pop up on ingredients lists.

Then there’s the consideration of a fiber’s fermentability (the rate at which it’s broken down in the gut). Fermentable fibers, Mangieri explains, act as prebiotics that can feed the digestive system with the “good bacteria” it needs to keep a balanced microbiome. Most prebiotic fibers are soluble, according to Mangieri, but some are insoluble.

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