What is the best fiber to take for constipation?

November 24, 2025 •

3 min read

According to the National Institute of Diabetes and Digestive and Kidney Diseases, constipation is one of the most common digestive problems in the United States, and increasing your fiber intake is often the first line of defense. This article explores what is the best fiber to take for constipation, differentiating between soluble and insoluble fiber and examining popular supplements.

Quick Summary

This guide provides a detailed look at fiber supplements and dietary sources for constipation relief, evaluating different types like psyllium, methylcellulose, and calcium polycarbophil, and emphasizing the importance of hydration for effectiveness.

Key Points

Psyllium is highly effective: The soluble fiber psyllium (found in products like Metamucil) is a top recommendation for chronic constipation due to its ability to soften and bulk stool.
Combine soluble and insoluble fiber: For comprehensive relief, incorporating both types of fiber from foods or supplements can be most effective for regular bowel movements.
Hydration is critical: Drinking plenty of water is essential when increasing fiber intake, as insufficient fluid can worsen constipation and cause blockages.
Natural food sources are best: Whole foods like prunes, kiwis, beans, and whole grains provide a wide range of nutrients in addition to fiber and are preferred over supplements when possible.
Synthetic options cause less gas: Methylcellulose (Citrucel) and Calcium Polycarbophil (FiberCon) are synthetic bulk-forming fibers that are good alternatives for those who experience bloating with natural fiber sources.
Start low and go slow: To minimize side effects like gas and bloating, gradually increase your fiber intake over several days or weeks.
Consult a professional: Before starting any new supplement regimen, especially for chronic constipation, talk to a doctor or dietitian.

Understanding the Two Main Types of Fiber

Fiber plays a crucial role in digestive health, and for constipation, it is important to understand the two different types: soluble and insoluble fiber.

Soluble Fiber: This type of fiber dissolves in water and forms a gel-like substance in the digestive tract. This gel helps soften hard stools, making them easier to pass. Excellent sources include oats, peas, beans, apples, carrots, and the popular supplement psyllium.
Insoluble Fiber: This fiber does not dissolve in water. Instead, it adds bulk to the stool and speeds up its movement through the intestines, which can be very effective for promoting regularity. Good dietary sources include whole-wheat flour, wheat bran, nuts, green beans, and potatoes.

For constipation, a combination of both types may provide the most comprehensive relief, although some research suggests non-fermentable soluble fibers like psyllium may be most effective.

Popular Fiber Supplements for Constipation

Fiber supplements can help when dietary changes aren't enough. Always take them with plenty of water to prevent blockages.

Psyllium (e.g., Metamucil, Konsyl)

Psyllium is a widely recommended soluble, gel-forming fiber from Plantago ovata seeds. It absorbs water to create a soft, bulky gel, increasing stool frequency and softening consistency. Generally well-tolerated, it works for chronic constipation and mild diarrhea. Side effects can include bloating and gas.

Methylcellulose (e.g., Citrucel)

This synthetic, non-fermentable soluble fiber adds bulk to stool and pulls in water to soften it. It's less likely to cause gas and bloating than some other fibers but requires plenty of water.

Calcium Polycarbophil (e.g., FiberCon)

Another synthetic fiber, it absorbs water to add bulk and moisture, making stool softer and easier to pass. It generally causes less gas than psyllium. Plenty of fluid is necessary, and it should not be used for more than 7 days without medical advice.

Inulin (Chicory Root Fiber)

Inulin is a soluble, prebiotic fiber found in foods like chicory root. It ferments in the bowel, stimulating beneficial bacteria, which may increase stool frequency and soften stools. Side effects can include gas, bloating, and cramping, especially at high doses. Evidence for its effectiveness in treating constipation may be limited compared to psyllium.

Comparison of Common Fiber Supplements


Feature	Psyllium	Methylcellulose	Calcium Polycarbophil	Inulin
Fiber Type	Soluble (Gel-forming)	Soluble (Non-fermentable)	Soluble/Synthetic (Absorbent)	Soluble (Prebiotic/Fermentable)
Mechanism	Forms a soft, bulky gel in intestines.	Adds bulk and water to stool.	Absorbs water to soften and bulk stool.	Fermented by gut bacteria.
Common Side Effects	Bloating, gas	Less bloating/gas than psyllium.	Less bloating/gas than psyllium.	Gas, bloating, cramps.
Risk of Bloating	Moderate	Low	Low	High
Natural Source	Yes, from Plantago seeds.	No, synthetic.	No, synthetic.	Yes, from chicory root.
Effect on Diarrhea	Can also help with mild diarrhea.	Primarily for constipation.	Primarily for constipation.	Can cause diarrhea in high doses.

A Note on Dietary Fiber vs. Supplements

Fiber from whole foods is generally preferred due to the additional nutrients they provide. To increase dietary fiber, eat more fruits (prunes, apples), vegetables (broccoli, leafy greens), legumes (beans, lentils), and whole grains (oatmeal, brown rice). Prunes and kiwi are known for their natural laxative effect.

Conclusion

For the question "what is the best fiber to take for constipation?", psyllium and methylcellulose are highly recommended options. Psyllium, a natural soluble fiber, is often a top choice backed by strong evidence. Methylcellulose is a good alternative if psyllium causes gas or bloating. The best fiber varies per individual. Adequate hydration is crucial for any fiber to work safely and effectively. A balanced approach combining dietary fiber and supplements as needed is often best. Consult a healthcare professional before starting new supplements.

Frequently Asked Questions

Both soluble and insoluble fibers are important for digestive health, but for constipation relief, both are beneficial. Soluble fiber softens hard stools, while insoluble fiber adds bulk to speed things along. Combining both, often found in whole foods, is often most effective.

Most bulk-forming fiber supplements, such as psyllium and methylcellulose, typically take anywhere from 12 hours to 3 days to produce a bowel movement. It's important to be patient and consistent with your dosage.

Yes, it is generally recommended to get fiber from whole food sources, as they provide a wider range of beneficial nutrients. Foods like fruits, vegetables, legumes, and whole grains are excellent sources. Supplements are best for when dietary intake is insufficient.

Methylcellulose (found in Citrucel) and Calcium Polycarbophil (found in FiberCon) are synthetic, non-fermentable fibers, meaning they are less likely to be broken down by gut bacteria and therefore produce less gas and bloating than fermented fibers like inulin or psyllium.

The Dietary Guidelines for Americans recommend a daily fiber intake of 25 to 34 grams, depending on your recommended daily calorie intake. Unfortunately, most people do not meet this goal.

For chronic constipation, many people can safely take fiber supplements like psyllium daily. However, it is best to consult a healthcare provider for personalized advice, especially if you have an underlying health condition or are taking other medications.

Prunes are known for their laxative effect, containing both fiber and sorbitol. Some studies have shown that prunes may be more effective than some fiber supplements like psyllium, though individual results can vary.