Wheat bran: more stool and faster transit, with firmer stools

Wheat bran does one thing that holds up in pooled trials. A 2025 review by the US Agency for Healthcare Research and Quality combined five wheat bran arms from four crossover trials in adults with normal bowels. Adding 5 to 28.7 g of bran fiber a day raised daily stool weight by 59 g (95% CI 28.5 to 90.3 g), though three of the four trials carried a high risk of bias and their results varied widely. The same trials shortened gut transit by 16.4 hours on average (95% CI 3.4 to 29.3 hours), with one trial going the other way. Softer stools were not part of the result. In the two trials that measured consistency, stools came out firmer, by 0.4 to 1.1 points on the 7-point Bristol scale. The review found no wheat bran trial in people with normal bowels that reported constipation itself as an outcome, so relief from constipation is something this evidence does not test.

The numbers, per 3.5 oz (100 g)

As people eat it, per 3.5 oz (100 g)

How much is actually in it

• Per 100 g, crude wheat bran in the US database has 42.8 g fiber, 15.6 g protein, 611 mg magnesium, 10.6 mg iron and 216 calories. — USDA FNDDS survey food 'Wheat bran', food code 57601100 Evidence E source
  Fiber 42.8 g, protein 15.55 g, fat 4.25 g, magnesium 611 mg, iron 10.57 mg, zinc 7.27 mg, phosphorus 1013 mg, selenium 77.6 mcg, 216 calories per 3.5 oz (100 g)
• UK tables agree on fiber (41.3 g per 3.5 oz (100 g)) but give much less magnesium (389 mg) and selenium (14 micrograms) than US data, so mineral content depends on where the wheat grew. — CoFID 2021 entry 11-906 Bran, wheat Evidence E source
  Fiber 41.3 g, magnesium 389 mg, selenium 14 mcg, iron 8.6 mg, zinc 5.6 mg, 186 calories per 3.5 oz (100 g) vs USDA 42.8 g, 611 mg, 77.6 mcg

What a real portion looks like

• A cup of wheat bran weighs 2.1 oz (60 g) in the US survey, but the default amount people report is 8 g, about 3.4 g of fiber. — USDA FNDDS portion weights for 'Wheat bran', food code 57601100 Evidence E source
  1 cup 60 g (25.7 g fiber); quantity not specified 8 g (3.4 g fiber), recalculated from 100 g

What your body absorbs

• Eaten with a cereal containing 16 g wheat bran, calcium absorption stayed near 23% at every dose, against 38 to 77% when the same calcium was taken without bran. — healthy adult women, randomized crossover, calcium carbonate labeled with 45Ca Evidence B source
  Fractional absorption 0.230 with bran vs 0.769 (0.5 mmol) to 0.378 (12.5 mmol) without
• Standard wheat bran blocked the rise in blood zinc after a 50 mg zinc dose almost completely, while reduced-phytate bran blocked about 76% of it. — three groups of healthy subjects given 50 mg zinc with or without a bran cereal Evidence B source
  AUC reduction 106.4% with standard bran vs 75.9% with reduced phytate bran vs 46.3% with a rice cereal
• Bioprocessing the bran in whole wheat bread made its phenolic acids 2 to 3 times more available in 8 men who ate 11 oz (300 g) of the bread. — 8 healthy men, crossover, 300 g whole wheat bread with native or bioprocessed bran (n = 8) Evidence B source
  Ferulic, vanillic, sinapic and 3,4-dimethoxybenzoic acid bioavailability 2 to 3-fold

What cooking and storage change

• The AGA-ACG guideline warns that finely ground wheat bran can lower stool water and harden stool, and names flatulence as the main side effect of fiber. — adults with chronic idiopathic constipation Evidence E source
  Fine bran powder may harden stool; flatulence the chief side effect
• In two crossover RCTs adding about 19 g of bran fiber a day, both fine and coarse wheat bran increased stool bulk over a low fiber control, with no difference in stool water. — healthy adults, metabolic study n=23 and ad libitum cereal study n=24 (n = 47) Evidence B source
  Fecal bulk increased vs control (p<0.004) with fine and coarse bran; no difference between particle sizes or in fecal water

What it does to your health

• A 2026 network meta-analysis of 17 RCTs in 1,423 adults with chronic constipation ranked insoluble fibers such as bran highest for overall symptom scores, but only on very low certainty evidence. — adults with chronic idiopathic constipation in 17 randomized controlled trials, searched to October 2025 (n = 1423) Evidence A source
  Insoluble fiber top SUCRA rank for overall symptom score (very low certainty); viscous soluble fibers better for straining (high certainty), stool consistency and frequency (moderate)
• The same trial found bran did no better than placebo on the symptoms that come with constipation. — 24 patients with chronic nonorganic constipation (n = 24) Evidence B source
  Occurrence and severity of accompanying symptoms not different between bran and placebo
• In a double-blind crossover RCT in healthy men, about 20 g of added wheat fiber a day for 10 days raised stool frequency from 1.1 to 1.3 a day without more gut complaints. — healthy male volunteers, meal boxes for 10 days Evidence B source
  Stool frequency 1.3 vs 1.1 defecations/day (p<0.05); fecal wet weight x1.41, dry weight x1.55; consistency and GI complaints unchanged
• Across five wheat bran arms in four crossover RCTs, adding 5 to 28.7 g of bran fiber a day raised total stool weight by 59 g a day. — adults with normal bowel function, four crossover RCTs, 2 to 3 weeks per intervention Evidence A source
  Total fecal weight +59.4 g/day (95% CI 28.5 to 90.3), dose slope 3.3 g per g/day fiber (95% CI 1.69 to 4.98)
• Wheat bran shortened gut transit time by about 16 hours on average across four crossover RCTs in people with normal bowel function. — adults with normal bowel function, four crossover RCTs, 2 to 3 weeks Evidence A source
  Transit time -16.4 h (95% CI -29.3 to -3.4), not dose-related
• Pooling 65 intervention studies, each extra gram of wheat fiber a day added about 3.7 g to daily stool weight and cut transit by 0.78 hours in people starting above 48 hours. — 65 intervention studies in generally healthy people Evidence C source
  +3.7 g/d total stool weight (95% CI 3.50 to 3.84) per g/d wheat fiber, transit -0.78 h per g/d
• Nine months of 13.5 g wheat bran fiber a day did not slow rectal cell proliferation in 93 people after removal of colorectal adenomas. — 93 evaluable participants with resected colorectal adenomas, 9 months (n = 93) Evidence B source
  No significant change in rectal mucosal thymidine labeling at 3 or 9 months

Safety, limits and interactions

• The guideline advises that fiber supplements are typically taken with 8 to 10 ounces of fluid, and that people who drink little are more likely to be constipated. — adults with chronic constipation Evidence E source
  Standard fiber dose taken with 8 to 10 oz (about 240 to 300 ml) of fluid
• On a metabolic ward, 20 g of wheat bran a day raised stool output from 150 to 246 g within 6 days without more gut symptoms, and 40 g worked no better than 20 g. — 60 subjects on a metabolic ward, 3 days baseline and 6 days treatment (n = 60) Evidence B source
  Stool output placebo 150 vs bran 246 g/day (p<0.05); BM/day 2.2 vs 2.6; no stool softening; 40 g/day not different from 20 g/day
• When 20 low-fiber eaters doubled fiber intake with wheat bran, pectin and banana flour for 14 days, drinking 2.1 quarts (2 liters) of water a day cut transient abdominal symptoms from 9 people to 3. — 20 healthy low-habitual fiber consumers, 14 days, fiber with or without 2 l water daily (n = 20) Evidence B source
  Abdominal symptoms 3 vs 9 participants (P = 0.020); fecal weight 71 to 126 g in the water group

What people believe that the data does not support

• The same network meta-analysis of 17 RCTs in 1,423 adults found viscous soluble fibers such as psyllium relieved straining better than placebo with high certainty, a stronger result than any shown for bran. — adults with chronic idiopathic constipation in 17 randomized controlled trials (n = 1423) Evidence A source
  Viscous soluble fiber vs placebo: defecation difficulty improved (high certainty, class 1); stool consistency and frequency improved (moderate certainty)
• In the two trials that measured consistency, wheat bran made stools firmer, by 0.4 to 1.1 points on the 7-point Bristol scale. — adults with normal bowel function, three wheat bran arms in two trials Evidence A source
  Stool consistency harder with bran in both trials, mean differences between arms -1.1 to -0.4 on the 7-point Bristol scale
• The EU authorizes the claim that wheat bran fiber speeds up intestinal transit. — EU Register on nutrition and health claims Evidence E source
  Status authorized
• The EU also authorizes the claim that wheat bran fiber increases fecal bulk. — EU Register on nutrition and health claims Evidence E source
  Status authorized

Who this works differently for

• In a double-blind crossover RCT of 24 people with chronic constipation, 20 g of bran a day for 4 weeks beat placebo on bowel frequency and transit, but only normalized transit in those with slow colonic transit. — 24 patients with chronic nonorganic constipation, crossover, two 4-week periods (n = 24) Evidence B source
  Bran 20 g/day superior to placebo for bowel frequency and oroanal transit; transit normalized only with slow colonic (not rectal) transit; symptoms no different from placebo
• A Cochrane review of 2 trials found fiber supplements raised stool frequency in pregnancy (odds ratio 0.18 for no improvement) and concluded bran or wheat fiber likely helps, with stimulant laxatives as the stronger next step. — pregnant women with constipation, 2 randomized trials (n = 2 trials) Evidence A source
  Fiber supplements increased defecation frequency (OR 0.18, 95% CI 0.05 to 0.67) and softened stools
• A meta-analysis of 22 trials in irritable bowel syndrome found soluble fiber improved symptoms (risk ratio 1.49) while insoluble fiber such as bran improved no outcome. — outpatients with irritable bowel syndrome in randomized and crossover trials vs placebo (n = 22 trials) Evidence A source
  Soluble fiber RR 1.49 (95% CI 1.09 to 2.03) for global symptoms; insoluble fiber no improvement in any outcome
• In a 12-week primary care RCT of 275 people with IBS, 10 g of bran helped only in month three, and early dropout was highest on bran, mostly because symptoms got worse. — 275 patients aged 18 to 65 with irritable bowel syndrome in general practice (n = 275) Evidence B source
  Bran vs placebo responders month 3: 57% vs 32%, RR 1.70 (1.12 to 2.57), not significant in worst case analysis (1.45, 0.97 to 2.16); psyllium effective from month 1
• In 39 young Korean women with functional constipation, a wheat based diet for 4 weeks cut colon transit time by about 17 hours compared with a white rice diet. — 39 young women with functional constipation, 13 per group, open randomized parallel design, 4 weeks (n = 39) Evidence B source
  Total colon transit time wheat diet -17.1 ± 11.9 h vs white rice +6.8 ± 2.1 h (p=0.022)
• In irritable bowel syndrome, a review of 17 RCTs found insoluble fiber such as wheat bran gave no benefit over placebo (relative risk 0.89) and sometimes worsened symptoms. — patients with irritable bowel syndrome in 17 randomized trials, secondary care Evidence A source
  Insoluble fiber RR 0.89 (95% CI 0.72 to 1.11) for global symptom relief vs soluble fiber RR 1.55
• In 17 kidney stone patients with high urine calcium, adding 30 g of wheat bran fiber cut urine calcium by 23.5% against 5.6% with diet alone, but oxalate fell only 3.9% against 21.4%. — 17 hypercalciuric patients with urolithiasis on low-calcium, low-oxalate diets (n = 17) Evidence B source
  Calciuria -23.5% vs -5.6%; oxaluria -3.9% vs -21.4% (bran vs diet alone)
• In 29 healthy children aged 8 to 12, a wheat bran extract was well tolerated at doses up to 5 g a day over 3 weeks. — 29 healthy children aged 8 to 12, crossover, 3 weeks (n = 29) Evidence B source
  Bifidobacteria share higher (P = 0.002), GI symptom scores unchanged

What is still unknown

• The 2023 AGA-ACG guideline found only one small bran trial in chronic constipation, with a possible gain of 1.3 bowel movements a week and a confidence interval that included no effect. — adults with chronic idiopathic constipation; one small crossover RCT (n = 1 trial) Evidence E source
  Spontaneous bowel movements per week MD 1.30 (95% CI -0.98 to 3.58); 1 adverse event vs 0 (RR 2.79, 0.12 to 62.48)
• The AGA-ACG panel rated the certainty of evidence for bran in chronic constipation as very low because of weak randomization and very serious imprecision. — adults with chronic idiopathic constipation Evidence E source
  Certainty of evidence very low
• The 2025 US agency review found no wheat bran trial in people with normal bowels that reported constipation itself as an outcome. — trials of wheat bran fiber vs no added fiber Evidence A source
  Zero trials with constipation outcome

The bottom line

Per 100 g, US data list crude wheat bran at 42.8 g fiber, 611 mg magnesium and 216 calories. UK tables agree on fiber at 41.3 g but give 389 mg magnesium and 14 micrograms of selenium against 77.6 micrograms in the US figures, and neither table explains the gap. The amount people actually report eating is small. The US survey default is 8 g, about 3.4 g of fiber, while a full cup weighs 2.1 oz (60 g). A wider review of 65 intervention studies of mixed design, not all randomized, puts the effect at about 3.7 g more stool a day for each extra gram of wheat fiber. The EU allows wheat bran fiber to be labeled as speeding intestinal transit and as increasing fecal bulk. Bran holds on to minerals eaten with it. In a randomized crossover trial in healthy women, calcium carbonate taken with a cereal containing 16 g wheat bran was absorbed at about 23% whatever the calcium load, and the abstract does not say how many women took part. In a 1989 study using a pharmacological 50 mg zinc dose, standard bran blocked the rise in blood zinc almost completely and a reduced-phytate bran blocked about 76% of it. Processing can push the other way. In 8 healthy men eating 11 oz (300 g) of bread once, bioprocessed bran made four phenolic acids 2 to 3 times more available than ordinary bran, a blood measure with no health outcome attached. Nine months of 13.5 g wheat bran fiber a day did not significantly change rectal cell proliferation in 93 people who had colorectal adenomas removed. That trial measured a biomarker and did not follow whether polyps came back. In 29 healthy children aged 8 to 12, an extract of arabinoxylan oligosaccharides made from wheat bran was well tolerated at up to 5 g a day for 3 weeks. Some people should be careful. In irritable bowel syndrome, a 2004 review of 17 randomized trials in hospital clinics found insoluble fiber such as wheat bran no better than placebo for overall symptom relief (relative risk 0.89, 95% CI 0.72 to 1.11), and in some trials it made symptoms worse. For calcium kidney stones, a small 1990 trial in 17 patients on low calcium, low oxalate diets saw urine oxalate fall 3.9% with 30 g of wheat bran fiber added, against 21.4% on the diet alone. Anyone relying on a calcium or zinc supplement should know the absorption trials above gave the mineral together with bran. Adding a lot of fiber quickly brings passing gut symptoms. When 20 healthy low-fiber eaters doubled their fiber for 14 days with a mix of bran, pectin and banana flour, 3 had abdominal symptoms while drinking 2.1 quarts (2 liters) of water a day, against 9 in the group without the extra water.

Sources

1. whbr-r2-01 · food composition dataset
   Wheat bran, FNDDS code 57601100, fdc_id 2708488: Energy 216.0 KCAL, Protein 15.55 G, Total lipid (fat) 4.25 G, Fiber, total dietary 42.8 G, Magnesium, Mg 611.0 MG, Iron, Fe 10.57 MG, Zinc, Zn 7.27 MG, Phosphorus, P 1013.0 MG, Selenium, Se 77.6 UG per 100 g
   USDA FoodData Central, FNDDS survey foods release 2024-10-31 · checked 2026-09-30
2. whbr-r2-02 · food composition dataset
   11-906 Bran, wheat: AOAC fibre 41.3 g; Energy 186 kcal; Protein 14.8 g; Fat 5.5 g; Iron 8.60 mg; Magnesium 389 mg; Phosphorus 1078 mg; Selenium 14 µg; Zinc 5.6 mg
   CoFID 2021, Public Health England, OGL v3.0, code 11-906 · checked 2026-09-30
3. whbr-r2-03 · food composition dataset
   Wheat bran, fdc_id 2708488: 1 cup 60 g; Quantity not specified 8 g; Fiber, total dietary 42.8 G per 100 g
   USDA FoodData Central, FNDDS survey foods release 2024-10-31 · checked 2026-09-30
4. whbr-r2-10 · randomized crossover trial
   In contrast, fractional absorption from calcium carbonate co-ingested with 40 g of a cereal product containing 16 g wheat bran, across a calcium load range from 0.5 to 15.5 mmol, was essentially constant (mean for all loads: 0.230 +/- 0.069).
   J Nutr, 1996 · checked 2026-09-30
5. whbr-r2-11 · randomized controlled trial
   The percentage reductions in AUC produced by the test meals were: standard bran 106.4 +/- 2.4, reduced phytate bran 75.9 +/- 4.8, Rice Krispies 46.3 +/- 10.4 per cent, P less than 0.01).
   Eur J Clin Nutr, 1989 · checked 2026-09-30
6. whbr-r2-12 · randomized crossover trial
   The bioavailabilities of ferulic acid, vanillic acid, sinapic acid, and 3,4-dimethoxybenzoic acid from the bioprocessed bread were 2- to 3-fold those from the control bread.
   J Nutr, 2011 · checked 2026-09-30
7. ev-wbcon-10 · guideline
   In addition, wheat bran can exist as a finely ground powder that can decrease stool water content and harden stool (34). The chief side effect of fiber supplementation seems to be flatulence.
   Am J Gastroenterol, 2023 · checked 2026-10-07
8. ev-wbcon-12 · randomized controlled trial
   In both studies, wheat bran supplements significantly increased fecal bulk compared to the control (p<0.004), with no significant differences between brans of different particle size and no differences in fecal water content.
   J Am Coll Nutr, 1999 · checked 2026-10-07
9. ev-wbcon-01 · network meta-analysis
   Insoluble dietary fibers showed the highest ranking probability for improvement in overall constipation symptom scores; however, this finding was supported by very low certainty evidence.
   Food Funct, 2026 · checked 2026-10-07
10. ev-wbcon-06 · randomized controlled trial
    Neither the occurrence nor the severity of the most frequent accompanying symptoms of chronic constipation differed significantly between placebo and bran treatments.
    Dig Dis Sci, 1995 · checked 2026-10-07
11. ev-wbcon-14 · randomized controlled trial
    Extrinsic wheat fibre intervention furthermore increased stool frequency (1.3 ± 0.1 defecations per day compared to 1.1 ± 0.1 defecations per day during control diet, p < 0.05), but did not affect stool consistency, satiety, gastrointestinal complaints or product liking.
    Food Funct, 2019 · checked 2026-10-07
12. whbr-r2-04 · systematic review of RCTs
    Meta-analysis across the five trials, not accounting for fiber dose, found a statistically significant higher total fecal weight (59.4 g/day; 95% CI 28.5 to 90.3) when consuming wheat bran (Figure 34).
    AHRQ 2025, Fiber Intake and Laxation in People With Normal Bowel Function: Systematic Review · checked 2026-09-30
13. whbr-r2-05 · systematic review of RCTs
    Meta-analysis, not accounting for fiber dose, identified a statistically significant shorter transit time with consumed wheat bran of −16.4 hours (95% CI −29.3 to −3.4) (Figure 36).
    AHRQ 2025, Fiber Intake and Laxation in People With Normal Bowel Function: Systematic Review · checked 2026-09-30
14. whbr-r2-08 · systematic review
    Weighted regression analyses demonstrated that each extra g/d of wheat fiber increased total stool weight by 3.7 ± 0.09 g/d (P < 0.0001; 95%CI: 3.50-3.84), dry stool weight by 0.75 ± 0.03 g/d (P < 0.0001; 95%CI: 0.69-0.82), and stool frequency by 0.004 ± 0.002 times/d (P = 0.0346; 95%CI: 0.0003-0.0078).
    World J Gastroenterol, 2015 · checked 2026-09-30
15. whbr-r2-14 · randomized controlled trial
    Neither the wheat bran fiber nor the calcium carbonate supplements significantly reduced [3H]thymidine LI percentages in rectal mucosal crypts (total or compartmental analysis) or 24-h in vitro outgrowth cultures at either 3 or 9 months of daily supplementation in the 93 evaluable participants.
    Cancer Epidemiol Biomarkers Prev, 1997 · checked 2026-09-30
16. ev-wbcon-11 · guideline
    Thus, efforts to increase fluid intake should be focused on those with low levels of fluid intake (35). Standard doses of fiber supplements are typically taken with 8–10 ounces of fluid (36).
    Am J Gastroenterol, 2023 · checked 2026-10-07
17. ev-wbcon-13 · randomized controlled trial
    Wheat bran 40 g/day results were not significantly different from wheat bran 20 g/day.
    Am J Gastroenterol, 2000 · checked 2026-10-07
18. whbr-r2-16 · randomized controlled trial
    Transient abdominal symptoms occurred less frequently in the fibre/water than in the fibre group (3 vs. 9 participants; p = 0.020).
    Int J Food Sci Nutr, 2022 · checked 2026-09-30
19. ev-wbcon-02 · network meta-analysis
    NMA suggested that viscous soluble fibers were associated with greater efficacy compared with placebo in relieving defecation difficulty (high certainty, class 1), and were also associated with improvements in stool consistency and stool frequency relative to placebo (moderate certainty, class 1).
    Food Funct, 2026 · checked 2026-10-07
20. whbr-r2-06 · systematic review of RCTs
    In both trials stool consistency was harder for participants ingesting wheat bran, with MD between arms ranging from −1.1 to −0.4 (standardized to the 7-point BSS).
    AHRQ 2025, Fiber Intake and Laxation in People With Normal Bowel Function: Systematic Review · checked 2026-09-30
21. whbr-r2-17 · regulatory decision
    POL-HC-6528 Wheat bran fibre Wheat bran fibre contributes to an acceleration of intestinal transit Authorised
    EU Register on nutrition and health claims, claim POL-HC-6528, snapshot 2026-09-21 · checked 2026-09-30
22. whbr-r2-18 · regulatory decision
    POL-HC-6529 Wheat bran fibre Wheat bran fibre contributes to an increase in faecal bulk Authorised
    EU Register on nutrition and health claims, claim POL-HC-6529, snapshot 2026-09-21 · checked 2026-09-30
23. ev-wbcon-05 · randomized controlled trial
    During bran treatment oroanal transit time became normal only in patients with slow colonic transit and not in those with slow rectal transit.
    Dig Dis Sci, 1995 · checked 2026-10-07
24. ev-wbcon-07 · Cochrane systematic review
    Dietary supplements of fibre in the form of bran or wheat fibre are likely to help women experiencing constipation in pregnancy.
    Cochrane Database Syst Rev, 2001 · checked 2026-10-07
25. ev-wbcon-08 · meta-analysis
    Soluble fiber appears to improve symptoms of IBS, whereas there is no evidence for recommending insoluble fiber for IBS.
    Eur J Gastroenterol Hepatol, 2015 · checked 2026-10-07
26. ev-wbcon-09 · randomized controlled trial
    Early dropout was most common in the bran group; the main reason was that the symptoms of irritable bowel syndrome worsened.
    BMJ, 2009 · checked 2026-10-07
27. ev-wbcon-15 · randomized controlled trial
    The TCTT of the BRD group was significantly reduced (p = 0.028) compared with the WRD group (-16.5 ± 8.1 vs +6.8 ± 2.1), and the TCTT of the WD group was also significantly reduced (p = 0.022) compared with that of the WRD group (-17.1 ± 11.9 vs +6.8 ± 2.1).
    Eur J Clin Nutr, 2020 · checked 2026-10-07
28. whbr-r2-09 · systematic review of RCTs
    Soluble fibre (psyllium, ispaghula, calcium polycarbophil) showed significant improvement (relative risk, 1.55; 95% CI, 1.35-1.78), whereas insoluble fibre (corn, wheat bran), in some cases, worsened the clinical outcome, but there was no significant difference compared with placebo (relative risk, 0.89; 95% CI, 0.72-1.11).
    Aliment Pharmacol Ther, 2004 · checked 2026-09-30
29. whbr-r2-13 · randomized controlled trial
    Oxaluria was decreased 21.4 percent by diet alone compared with 3.9 percent in the diet and fiber treatment group.
    Urology, 1990 · checked 2026-09-30
30. whbr-r2-15 · randomized crossover trial
    WBE is well tolerated at doses up to 5 g/day in healthy preadolescent children.
    J Pediatr Gastroenterol Nutr, 2014 · checked 2026-09-30
31. ev-wbcon-03 · guideline
    Based on this 1 small study, bran may lead to an increase in SBMs per week; however, the CI was wide and included a possible null effect (MD 1.30, CI −0.98 to 3.58) (26).
    Am J Gastroenterol, 2023 · checked 2026-10-07
32. ev-wbcon-04 · guideline
    We are very uncertain about the effects of bran. The overall certainty of evidence for bran is very low because of concerns about the adequacy of randomization and allocation concealment as well as very serious imprecision (26).
    Am J Gastroenterol, 2023 · checked 2026-10-07
33. whbr-r2-07 · systematic review of RCTs
    No trials of wheat bran reported data for constipation.
    AHRQ 2025, Fiber Intake and Laxation in People With Normal Bowel Function: Systematic Review · checked 2026-09-30