Effects of cereal fiber on bowel function: A systematic review of intervention trials

Table 1 Summary of comparisons for different intact cereal dietary fibers and bowel function outcomes

	Source of intact fiber
	Wheat	Barley	Corn	Oat	Rice	Rye	Sorghum
Total stool weight
Observations1, n	75	3	4	1	2	2	1
Fiber intervention (g/d), mean ± SD or range2	15.2 ± 8.3	10.2, 23	6.0, 42	14.3	17.1, 20.7	13, 20.6	2.5
Dry stool weight
Observations, n	40	1	3	1	1	1	-
Fiber intervention (g/d), mean ± SD or range2	14.7 ± 8.5	21	6, 42	14.3	20.7	20.6	-
Fecal water
Observations, n	30	3	2	-	1	-	-
Level of fiber interv. (g/d), mean ± SD or range2	16.0 ± 7.4	10.2, 23	15, 42	-	20.7	-	-
Stool frequency
Observations, n	34	2	2	-	2	2	1
Fiber intervention (g/d), mean ± SD or range2	13.6 ± 6.4	21, 23	15, 42	-	17.1, 20.7	20.6, 36.4	2.5
Transit time
Observations, n	52	-	-	1	2	1	1
Fiber intervention (g/d), mean ± SD or range2	14.8 ± 8,6	-	-	2.7	17.1, 20.7	20.6	2.5

¹May include > 1 observation from studies examining > 1 dose of intact cereal dietary fiber;

²Fiber intakes are shown as mean ± SD of all observations if > 5 observations were available, the range of values from individual studies if 2-4 observations were available, and a single estimate if only one observation was available.

Table 2 Fiber intakes and effects on total stool weight, dry stool weight, percentage water in stool, stool frequency, and transit time

	Source of intact cereal dietary fiber
	Wheat	Barley	Corn
Total stool weight
Observations, n	75	3	4
Fiber (g/d), mean ± SD or range	15.2 ± 8.3	10.2-23	6.0-42
Total effect (g/d), mean ± SD or range	65.4 ± 37.8	49.6-65	1.2-96.3
Average fecal bulking index, Δ in g/d stool weight per g/d fiber	4.7 ± 2.7	3.6 ± 2.4	2.1 ± 1.5
Fecal bulking index by regression, Δ in g/d stool weight per g/d fiber	3.67 ± 0.09b	-	-
	(3.50-3.84)
Dry stool weight
Observations, n	40	1	3
Fiber (g/d), mean ± SD or range	14.7 ± 8.5	-	6-42
Total effect (g/d), mean ± SD or range	14.4 ± 9.4	-	4.8-31
Fecal bulking index by regression, Δ in g/d stool weight per g/d fiber	0.75 ± 0.03b	-	0.7-0.9
	(0.69-0.82)
Fecal water
Observations, n	30	3	2
Fiber (g/d), mean ± SD or range	16.0 ± 7.4	10.2-23	-
Total effect by regression (∆% water), mean ± SD or range	1.5 ± 2.1	-1.8-10	-
Stool frequency
Observations, n	34	2	2
Fiber (g/d), mean ± SD or range	13.6 ± 6.4	-	-
Total effect (times/d), mean ± SD or range	0.34 ± 0.23	-	-
Frequency index by regression, Δ in times/d per g/d fiber	0.004 ± 0.002a	-	-
	(0.003-0.078)
Transit time
Observations, n	52	0	0
Fiber (g/d), mean ± SD	14.8 ± 8,4	-	-
Δ in h per g/d fiber by regression (those with initial transit time between 24-48 h)	0.78 ± 0.13b	-	-
	(0.53-1.04)
Δ in h per g/d fiber by regression (those with initial transit time between 48-96 h)	-0.75 ± 0.04b	-	-
	(-0.84- -0.67)

^aP < 0.05,

^bP < 0.01 vs control.