Table 2. Characteristics of Studies on Top Four Reported Fiber Types in Database (n = 437).
| Total | Guar Gum | Combination/Mixture | Psyllium | Dietary Fiber | |
|---|---|---|---|---|---|
| 437 | 129 (8.7) | 111 (7.5) | 100 (6.7) | 97 (6.5) | |
| Study Design | |||||
| RCT Crossover | 276 (63.2) | 97 (75.2) | 66 (59.5) | 53 (53.0) | 60 (61.9) |
| RCT Parallel | 131 (30.0) | 22 (17.1) | 40 (36.0) | 42 (42.0) | 27 (27.8) |
| Other1 | 30 (6.9) | 10 (7.7) | 5 (4.5) | 5 (5.0) | 10 (10.3) |
| Blinding | |||||
| Unspecified | 241 (55.1) | 80 (62.0) | 45 (40.5) | 39 (39.0) | 77 (79.4) |
| Double-blind | 131 (30.0) | 36 (27.9) | 54 (48.7) | 33 (33.0) | 8 (8.2) |
| Single-blind | 40 (9.1) | 8 (6.2) | 10 (9.0) | 18 (18.0) | 4 (4.1) |
| Not blinded | 24 (5.5) | 4 (3.1) | 2 (1.8) | 10 (10.0) | 8 (8.2) |
| Other2 | 1 (0.2) | 1 (0.8) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
| Age Category | |||||
| Adults (20+ y) | 331 (75.7) | 100 (77.5) | 75 (67.6) | 76 (76.0) | 80 (82.5) |
| Adults & Adolescents (12–20+ y) | 87 (19.9) | 22 (17.1) | 31 (27.9) | 20 (20.0) | 14 (14.4) |
| Other3 | 19 (4.3) | 7 (5.4) | 5 (4.5) | 4 (4.0) | 3 (3.1) |
| Study Diet | |||||
| Isocaloric/maintenance | 171 (39.1) | 35 (27.1) | 38 (34.2) | 53 (53.0) | 45 (46.4) |
| Acute feeding study | 170 (38.9) | 73 (56.6) | 48 (43.2) | 17 (17.0) | 32 (33.0) |
| Unspecified | 65 (14.9) | 15 (11.6) | 13 (11.7) | 26 (26.0) | 11 (11.3) |
| Hypocaloric | 23 (5.3) | 5 (3.9) | 9 (8.1) | 2 (2.0) | 7 (7.2) |
| Other4 | 8 (1.8) | 1 (0.8) | 3 (2.7) | 2 (2.0) | 2 (2.1) |
| Level of Feeding Control | |||||
| Food partially provided (partial metabolic) | 183 (41.9) | 57 (44.2) | 47 (42.3) | 61 (61.0) | 18 (18.6) |
| All food provided (metabolic) | 200 (45.8) | 69 (53.5) | 53 (47.8) | 25 (25.0) | 53 (54.6) |
| Food recommended | 23 (5.3) | 0 (0.0) | 3 (2.7) | 2 (2.0) | 18 (18.6) |
| Dietary guidance with supplement or fiber treatment provided | 18 (4.1) | 1 (0.8) | 5 (4.5) | 9 (9.0) | 3 (3.1) |
| Unspecified/other5 | 13 (3.0) | 2 (1.6) | 3 (2.7) | 3 (3.0) | 5 (5.1) |
| Baseline Health | |||||
| Healthy | 199 (45.5) | 60 (46.5) | 60 (54.1) | 39 (39.0) | 40 (41.2) |
| Metabolically at risk | 202 (46.2) | 59 (45.7) | 45 (40.5) | 50 (50.0) | 48 (49.5) |
| GI condition6 | 17 (3.9) | 2 (1.6) | 3 (2.7) | 9 (9.0) | 3 (3.1) |
| Mixed population | 16 (3.7) | 8 (6.2) | 1 (0.9) | 2 (2.0) | 5 (5.1) |
| Other7 | 3 (0.7) | 0 (0.0) | 2 (1.8) | 0 (0.0) | 1 (1.0) |
1 includes controlled trials with unspecified randomization, non-randomized trials, combined crossover and randomized controlled trial, and switch-back design
2 time-blinded
3 includes adolescents and studies where age information was not provided
4 includes AHA diet, weight loss diets, and combinations of maintenance or weight loss diets based on individual participant BMI
5 includes mixture of food provided and food partially provided, mixture of food partially provided and food recommended, and not specified
6 includes constipation, diverticular disease, fecal incontinence, loose stools, and hemorrhoids
7 includes recently removed colonic adenomas, or not reported