The 5 Best Fiber Supplements of 2023, According to a Dietitian

Who May Not Benefit From Fiber Supplements

Fiber supplements are safe for most people, though some conditions require caution.

Avoid fiber supplementation if you:

• Have difficulty swallowing
• Have impacted stool (stool that is hardened and stuck)
• Have bowel obstruction (blocked small or large intestine) 
• Have esophageal stricturing (narrowing of the esophagus) 
• Have active intestinal inflammation: such as diverticulitis and moderate to severe inflammatory bowel disease (IBD), including Crohn’s disease and Ulcerative Colitis.
• Already get adequate fiber: If you get enough dietary fiber from the food you eat, you may not benefit from a fiber supplement. Excess fiber can lead to constipation, gas, bloating, or diarrhea if added too quickly or with inadequate water intake.

Speak with a healthcare provider before starting a fiber supplement if you:

• Have slow transit constipation
• Have pelvic floor dysfunction
• Have gastroparesis (delayed stomach emptying)
• Have had recent gastrointestinal surgery 
• Are severely backed up: You may need to consider a laxative course to clear out excess stool before adding fiber.
• Have an unaddressed infection or disease that causes irregular bowel habits: You may not benefit from fiber supplements until the condition is treated by a healthcare provider.
• Take prescription medication or dietary supplements: Some fiber products can interfere with the absorption of medications and supplements, so it’s best to speak with a knowledgeable healthcare provider about possible interactions before beginning supplementation.

How We Select Supplements

Our team works hard to be transparent about why we recommend certain supplements; you can read more about our dietary supplement methodology here. 

We support supplements that are evidence-based and rooted in science. We value certain product attributes that we find to be associated with the highest quality products. We prioritize products that are third-party tested and certified by one of three independent third-party certifiers: USP, NSF, or ConsumerLab. 

It's important to note that the FDA does not review dietary supplements for safety and effectiveness before they go to market. Our team of experts has created a detailed, science-backed methodology to choose the supplements we recommend.

To come up with this list, we consulted with experts to discuss what to look for in fiber supplements. The experts we spoke to included:

• Laura Frado, MS, MD, a gastroenterologist at New York Gastroenterology Associates
• Registered Dietitian and author Tamara Duker Freuman, MS, RD, CDN
  

What to Look For

Third-Party Testing

Supplements that are third-party tested are sent to a lab where they are tested to ensure they contain what they say they contain and are not contaminated with specific high-risk, common contaminants. However, it’s important to note:

1. Third-party testing does not test to see if a product is effective or safe for everyone, and it does not ensure the supplement will not interact with other supplements or medications.
2. Not all third-party testing is created equal. It is not uncommon for supplement companies to pay labs for certificates after conducting minimal to no testing. 
3. The third-party certifications we can trust are: ConsumerLab, NSF, and USP. However, these certifications are difficult to obtain and/or expensive for manufacturers, so many companies choose not to get their products tested by one of these three organizations. 
4. Sometimes products tested by these three companies are more expensive to try to offset the cost they pay for certification.
5. Just because a supplement is not tested by one of these three companies, it does not mean it’s a bad product. We recommend doing some research on the reputability of the manufacturer and calling up the manufacturer and their testing lab to determine their protocols and decide if you feel comfortable consuming the supplement.

Most specific fiber supplements containing the fiber types with the strongest evidence are not third-party tested and may contain additives. However, they are included here if there is good research to support their benefit for regularity. Those with food allergies or intolerances should examine product ingredients and labels, as there may be sources of cross-contamination. Some fiber sources may contain gluten and are unsafe if you have celiac disease. 

Form

Physical form: Fiber supplements are most commonly found in pill (capsule), gummy, or powdered forms.

• Serving sizes can vary. For example, you may need to take more capsules or gummies to equal the same dose of a powdered form (i.e., five capsules versus one scoop of powder), which can make capsules and gummies more costly.
• Some fiber powders can be added to liquid with no taste or texture change, while others gel with water and may work better in moist foods (i.e., smoothies, breakfast porridges, soups). 
• Fiber gummies typically contain prebiotic fibers, which may not be effective.
  

Natural versus synthetic: Fiber sources can also be natural or synthetic. Both synthetic and natural fibers have proven results for stool-normalizing benefits.

• Natural fibers include psyllium husk and flaxseed.
• Synthetic fibers include methylcellulose and calcium polycarbophil.

Ingredients & Potential Interactions

It is essential to carefully read the ingredient list and nutrition facts panel of a supplement to know which ingredients and how much of each ingredient is included relative to the recommended daily value of that ingredient. Please bring the supplement label to a healthcare provider to review the different ingredients contained in the supplement and any potential interactions between these ingredients and other supplements and medications you are taking.

Sugar alcohols: Flavored fiber powders or gummies may include sweeteners known as sugar alcohols (i.e., xylitol or erythritol), which have been shown to promote gas and diarrhea.

Prebiotic fibers: Gummy products also usually contain inulin (chicory root fiber) or polydextrose fiber. Other fiber supplements may also contain prebiotic fibers as the main ingredients, though there is limited evidence for their benefits for regularity, and they may cause bloating and abdominal pain. Aside from inulin, other examples include galactooligosaccharides (GOS) and beta-glucans. Inulin is the most studied prebiotic and has some evidence for increasing stool frequency and beneficial gut bacteria, though with associated gas and bloating. If you have IBS or are already gassy, you may want to avoid prebiotic fibers until more data emerges for their use. 

Gluten: Some fiber sources may contain gluten and are unsafe for celiac disease. 

Probiotics: A number of fiber supplements include probiotics (specific strains of beneficial bacteria). However, there is not enough evidence that shows they are beneficial to help with pooping issues.

Interaction with medications: Fiber supplements may interfere with the body’s absorption of certain medications. It’s recommended that you take fiber two to four hours apart from medication, though always consult a healthcare provider about preexisting conditions and prescription regimens. Fiber supplements may interfere with:

• tricyclic antidepressants (Amitriptyline, Doxepin, Imipramine)
• diabetes medications (glyburide and metformin)
• carbamazepine
• cholesterol-lowering medications (Colestipol and cholestyramine)

If you take digoxin or lithium, you should avoid fiber supplements. Fiber can impact blood sugar levels, so you should monitor your glycemic response if you have diabetes. 

Fiber Dosage

Fiber needs vary based on your age, pre-existing conditions, diet pattern, and overall digestive health. General dietary guidelines recommend about 25 to 34 grams of fiber per day from food sources. The adequate intake of dietary fiber is 14 grams per 1,000 calories consumed. Recommended dietary fiber goals by age and sex assigned at birth (based on Dietary Reference Intakes for total calories) are as follows:

· 2 to 3 years: 14 grams (Males and Females)

· 4 to 8 Years: Females - 17g, Males - 20g

· 9 to 13 Years: Females - 22g Males - 25g

· 14 to 18 Years: Females - 25g, Males - 31g,

· 19 to 30 Years: Females - 28g, Males - 34g,

· 31 to 50 Years: Females – 25g, Males - 31g

· 51+ Years: Females - 22g, Males - 28g

The guidelines for dietary fiber were developed based on whole food sources, not supplements. The American Academy of Nutrition and Dietetics advises consuming fiber from fruits, vegetables, legumes, and whole grains to meet the recommended daily amount, though there are no set fiber amounts to prevent or treat gastrointestinal symptoms. In fact, fiber recommendations arose from a specific association between a high‐fiber diet and reduced risk for heart disease, not digestive disorders.

While individual fiber sources found in supplements have not been proven to provide the same benefits associated with a fiber-rich diet, they can still offer some help for pooping difficulties.  The amount of fiber supplement needed to improve your bowel habit will depend on the product, your diet, fluid intake, and individual response. Supplemental fiber should always be added in slowly and per the directions of a healthcare provider.

Always speak with a healthcare professional before adding a supplement to your routine to ensure that the supplement is appropriate for your individual needs and which dosage to take.

Too Much Fiber or Not Enough Fluids

While there is no Tolerable Upper Intake Level for fiber (the maximum daily amount that can be safely consumed), concentrated doses can cause constipation, gas, or bloating if you add it too quickly or without enough fluids.

Fiber supplements require adequate fluids. Most fiber supplements recommend 8 ounces of water with a standard dose, though individual product directions may vary. Inadequate fluid intake can cause the supplement to swell and lead to choking, blockages, or stool impaction, as well as gas, bloating, abdominal pain, and constipation.

Why Trust Verywell Health

Suzie Finkel, MS, RD, CDN, is a Registered Dietitian specializing in the nutritional management of digestive problems. She holds a master’s degree in nutrition from Columbia University and has trained in numerous clinical gastroenterology settings. As a GI dietitian, she provides evidence-based nutrition services for an array of conditions, including irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), constipation, and diarrhea. She utilizes fiber therapy often to help her patients improve their symptoms. Her goal is to demystify nutrition (mis)information and facilitate digestive comfort.