Best Fiber Supplements
Psyllium has the strongest clinical support. Methylcellulose and wheat dextrin are gentler options with less outcome data. Food fiber still comes first.
Quick Summary
Psyllium husk (Metamucil, Konsyl, or plain psyllium powder) is the best-supported fiber supplement for most adults.
If psyllium causes too much gas, methylcellulose (Citrucel) or wheat dextrin (Benefiber) are gentler, with less outcome evidence. Food fiber comes first. Supplements fill the gap.
💡Key takeaways
- The Dietary Guidelines recommend 14 g of fiber per 1,000 calories (28 g on a 2,000-calorie diet). More than 90% of women and 97% of men fall short (DGA 2020–2025).
- In a meta-analysis of 28 RCTs (1,924 people), about 10 g/day of psyllium lowered LDL cholesterol by 0.33 mmol/L, about 13 mg/dL (Jovanovski et al., AJCN 2018). The milligram figure is an Evident conversion: 1 mmol/L of cholesterol is about 38.67 mg/dL.
- Start low and build up with plenty of water. Bulk-forming fiber labels warn to mix each dose in at least 8 oz of liquid and drink it promptly, because of choking risk (Metamucil and Citrucel Drug Facts, DailyMed).
Fiber types compared
| Feature | Psyllium husk | Methylcellulose | Wheat dextrin | PHGG / inulin |
|---|---|---|---|---|
| Example | Metamucil Therapy for Regularity, sugar-free | Citrucel | Benefiber Original | Various brands |
| Fiber per dose | About 3.4 g psyllium husk per packet (DailyMed) | 2 g methylcellulose per dose (DailyMed) | 3 g fiber per 2 tsp (supplement facts) | Varies by product |
| Evidence | AGA/ACG 2023 constipation, ACG 2021 IBS, FDA 21 CFR 101.81, LDL meta-analysis | OTC bulk laxative for occasional constipation; less trial data than psyllium | Few clinical outcomes; easy to add to drinks | Mixed; inulin is fermentable and can worsen IBS symptoms |
| Gas and bloating | Moderate, especially early on | Low (not fermented) | Low to moderate; contains wheat (label) | Moderate to high for inulin |
Who should talk to a doctor first
People with trouble swallowing, a history of bowel obstruction, sudden changes in bowel habits, rectal bleeding, or abdominal pain. Also anyone taking medicines that need spacing from fiber. Labels advise separating doses. This is not medical advice.
How we checked
On October 21, 2026, we checked the Dietary Guidelines for Americans 2020–2025 fiber target, the Jovanovski 2018 LDL meta-analysis, 21 CFR 101.81, the 2023 AGA/ACG constipation guideline, the 2021 ACG IBS guideline, the DailyMed labels for Metamucil (setid a9824f73-5ea2-4a65-a926-3a57561441b8) and Citrucel (setid 9d5f2244-a610-4d45-b6e8-e79bb17a558f), and the Benefiber supplement-facts PDF. No affiliate links.
Frequently Asked Questions
Psyllium husk has the strongest clinical support for constipation, IBS symptoms, and LDL cholesterol (AGA/ACG 2023; ACG 2021; Jovanovski et al., AJCN 2018).
Metamucil is psyllium, which has more outcome evidence. Benefiber is wheat dextrin, which dissolves clear and may cause less gas, with less clinical outcome data.
The Dietary Guidelines recommend 14 g of fiber per 1,000 calories from food first, about 28 g on a 2,000-calorie diet. Supplements cover the gap. Start low and build up with water.
In a meta-analysis of 28 trials (1,924 people), about 10 g/day of psyllium lowered LDL by 0.33 mmol/L, about 13 mg/dL (Jovanovski et al., AJCN 2018). The milligram figure is an Evident conversion: 1 mmol/L of cholesterol is about 38.67 mg/dL. FDA permits a heart-disease risk claim at 7 g/day of soluble fiber from psyllium husk (21 CFR 101.81).
They can, especially fermentable fibers. Methylcellulose is not fermented, so it tends to cause less gas. Inulin can worsen IBS symptoms.
Any consistent time, mixed in a full glass of water and drunk promptly. Labels advise spacing fiber away from medicines.
Sources
- Dietary Guidelines for Americans, 2020–2025
- Jovanovski et al., American Journal of Clinical Nutrition (2018), psyllium and LDL
- 21 CFR 101.81, health claims for soluble fiber from psyllium husk
- AGA/ACG clinical practice guideline, chronic idiopathic constipation (2023)
- ACG clinical guideline, irritable bowel syndrome (2021)
- DailyMed, Metamucil Therapy for Regularity
- DailyMed, Citrucel
- Benefiber supplement facts (patient information PDF)
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