Types of Fiber

• Soluble fiber dissolves in water, forming a gel-like consistency in the gut that can help to slow digestion and promote fullness. Examples include oatmeal, psyllium husk, and flaxseeds.
• Insoluble fiber does not dissolve in water but adds bulk to the stool to promote regularity. Sources include whole grains, nuts, and seeds.
• Functional fibers are defined by the Institute of Medicine as "isolated, non-digestible carbohydrates that have been shown to have beneficial physiologic effects in humans." These benefits include lowering cholesterol, improved blood sugar management, and bowel movement regulation, depending on the type of functional fiber. Examples include psyllium husk, methylcellulose, calcium-polycarbophil, wheat dextrin, and inulin. They are not intended to replace dietary fiber intake from whole foods, which come with the added benefits of other nutritional properties.

Are Fiber Supplements Beneficial?

If you consume adequate amounts of dietary fiber and experience digestive regularity, you may not need a fiber supplement. If you have diarrhea, constipation, IBS, or another gastrointestinal issue, functional fiber supplements may or may not help. We recommend speaking to a healthcare provider to understand the underlying cause of the issue and to determine whether a fiber supplement would be appropriate. 

There are certain situations in which fiber supplements may be beneficial. These include:

• Those experiencing diarrhea: According to Finkel, if you have diarrhea and are considering fiber supplementation, you may benefit from a soft bulking agent that can act like a sponge in the bowel. These products are often mostly soluble fiber, which gel or swell with water. The appropriate product choice, however, will depend on what is driving the diarrhea.
• Those experiencing constipation: Finkel says if you’re constipated, it can be helpful to first look at the diet to ensure you consume adequate fiber from food. If you are getting enough fiber in your diet, adding more fiber from a supplement may not always be helpful for all constipation problems. If your diet could use a fiber boost, products such as psyllium husk can help gently bulk up stool and make it easier to pass.
• Those with IBS: If you have IBS, Finkel says to first consider diet changes and whether the symptoms are mainly diarrhea or constipation. There is evidence for using a soluble fiber supplement in IBS management. You may also want to avoid products with ingredients that can cause gas and bloating, such as sugar alcohols or inulin. 
• Those with high cholesterol: Soluble fiber may help lower levels of LDL cholesterol (“bad cholesterol”) by binding with cholesterol and removing it in the feces. If a healthcare provider has determined you have high cholesterol, you may want to discuss whether fiber supplementation is appropriate.
• Those with diabetes: Fiber supplements may benefit those with type 2 diabetes by reducing fasting blood sugar and HbA1c. If you have diabetes, speak to a healthcare provider about fiber supplementation, particularly if you take medications.

Who May Not Benefit from Fiber Supplements

Fiber supplements should not replace a balanced diet high in fiber-rich foods. There are also certain situations in which you should exercise caution with fiber supplements. You should avoid fiber supplements if you:

• Consume adequate fiber: If you eat enough dietary fiber, a fiber supplement may not be necessary. Excessive fiber intake can lead to gastrointestinal issues such as gas, bloating, diarrhea, or constipation. This can occur when you add too much too soon or do not consume enough liquids.
• Are taking certain medications: Fiber supplements can lower absorption of certain medications. If you are taking medications, including those for diabetes management, consult a healthcare provider before using fiber supplements.
• Have intestinal obstructions or fecal impact: Avoid bulk-producing laxatives if you have intestinal obstructions, as they can exacerbate the problem. You should first focus on treating the underlying condition under the guidance of a healthcare professional.
• Have inflammatory bowel diseases such as ulcerative colitis or Crohn’s disease: If you have an inflammatory bowel disease, you should speak with a healthcare provider before using fiber supplements.

How We Selected the Fiber 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 independently verified and certified by one of three independent certifiers: USP, NSF, or ConsumerLab.com. 

We also spoke with a gastrointestinal dietitian, a pediatric dietitian, and a registered dietitian nutritionist about what to look for when shopping for a high-quality fiber supplement and what to avoid.

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.

What to Look For

Independent Verification

Supplements that are independently verified 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. Independent verification 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 independent verification is created equal. It is not uncommon for supplement companies to pay labs for certificates after conducting minimal to no testing. 
3. The certifications we can trust are: ConsumerLab.com, 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 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.

Contamination with heavy metals such as lead, arsenic, and cadmium may be a risk with certain fiber supplements. Psyllium husk has been found to be contaminated with lead, so we chose one that has been tested and approved by ConsumerLab.com. However, most fiber supplements are not independently verified.

Form

Fiber supplements come in a variety of forms, including capsules, powders, or gummies, each with its own benefits and drawbacks. Capsules may be easy to take, but the serving size can vary between supplement brands. In some cases, many pills may be needed to meet your required dose. In addition, capsules need to be taken with adequate fluids and may not be best for people with swallowing difficulties.

Powder fiber supplements can often be added to liquids or soft foods, but some can thicken quickly in liquid, making them more suitable for baked goods. Gummies may contain added sugars or sugar alcohols, which may or may not suit your needs.

Ingredients and 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.

It is important to review ingredient labels, as some fiber supplements may contain additional ingredients that can result in GI upset. If you experience IBS, you may want to avoid products with ingredients such as sugar alcohols, inulin, or chicory root, as these can lead to gas or bloating for some. 

If you have diabetes or are managing your blood sugar levels, be aware fiber supplements can impact blood sugar levels and potentially interfere with diabetes medication. You may also want to check whether products contain added sugars. If you have diabetes, check with a healthcare professional before adding a fiber supplement.

Fiber supplements can also interact with your body’s ability to absorb certain medications, including tricyclic antidepressants, diabetes medications, carbamazepine, digoxin, or lithium. You may need to take medications one hour before or two to four hours after fiber supplementation. If you are taking medications, you should consult with a healthcare provider before incorporating fiber supplements.

Fiber Dosage

According to the 2020-2025 Dietary Guidelines for Americans, daily dietary fiber recommendations are as follows:

• Ages 2 to 3: males and females — 14 grams 
• Ages 4 to 8: males — 20 grams, females — 17 grams
• Ages 9 to 13: males — 25 grams, females — 22 grams
• Ages 14 to 18: males — 31 grams, females — 25 grams
• Ages 19-30: males — 34 grams, females — 28 grams
• Ages 31-50: males — 31 grams, females — 25 grams
• Ages 51+: males — 28 grams, females — 22 grams 

You should first focus on meeting your fiber needs through whole foods sources and consult a healthcare professional before turning to a fiber supplement. 

Our Experts

Our team of registered dietitians spoke with additional experts throughout the research, selecting, and reporting process. The following experts spoke with us about what key features to look for when shopping for a high-quality fiber supplement, its benefits, and who they may be helpful for. While we select products independently, expert input influences our decisions.

• Suzie Finkel, MS, RD, CDN, gastrointestinal dietitian at New York Gastroenterology Associates
• Jonathan Valdez, MBA, RDN, CDN, CCM, CDCES, ACE-CPT, registered dietitian nutritionist, certified personal trainer, and founder of Genki Nutrition
• Jennifer Friedman, MS, RD, pediatric dietitian and founder of Jennifer Friedman Nutrition

Why Trust Verywell Fit

Tamar Kane, MS, RD, is a Registered Dietitian, Verywell Fit nutrition writer, and marathon runner. She is the founder of Tamar Kane Nutrition, a virtual practice that focuses on helping runners learn to fuel their running and their lives. Tamar has her master's degree in Nutrition and Exercise Physiology from Teachers College, Columbia University, and specializes in working with plant-based athletes. Her goal is to help people understand how to properly fuel their bodies (and supplement if needed!) to optimize performance and well-being.

Additional reporting contributed by Eliza Savage, MS, RD, CDN, RYT

Eliza Savage, MS, RD, CDN, RYT, is a registered dietitian and Verywell Fit writer with a lifelong passion for wellness. Eliza has covered nutrition and fitness topics, testing products such as bone broth, Greek yogurt, and more. She has also written about gym equipment and sports, such as pickleball.