Table 1.
Study design characteristics of whole grain intervention trials in humans, organized by trial duration.
| Characteristic | Acute | Moderate (>1 Day––6 Weeks) | Long (>6 Weeks) | ||||||
|---|---|---|---|---|---|---|---|---|---|
| Total | RCT | Other 1 | Total | RTC | Other 2 | Total | RTC | Other 3 | |
| Number of trials, n | 118 | 101 | 17 | 63 | 57 | 6 | 32 | 31 | 1 |
| Parallel, n (%) | - | 1 (1) | - | - | 20 (35) | - | - | 26 (84) | - |
| Crossover, n (%) | - | 100 (99) | - | - | 37 (65) | - | - | 1 (3) | - |
| Duration, n (%) | |||||||||
| ≤ 1 day | 118 (100) | 101 (100) | 17 (100) | - | - | - | - | - | - |
| < 1 week | - | - | - | 10 (16) | 7 (12) | 3 (50) | - | - | - |
| 1 to 6 weeks | - | - | - | 53 (84) | 50 (88) | 3 (50) | - | - | - |
| 6 to 12 weeks | - | - | - | - | - | - | 25 (78) | 24 (77) | 1 (100) |
| >12 weeks | - | - | - | - | - | - | 7 (22) | 7 (23) | 0 (0) |
| Sample size, n (%) | |||||||||
| ≤10 | 39 (33) | 29 (29) | 10 (59) | 4 (6) | 2 (4) | 2 (33) | 0 (0) | 0 (0) | 0 (0) |
| 11–25 | 58 (49) | 54 (53) | 4 (24) | 27 (43) | 23 (40) | 4 (67) | 4 (13) | 4 (13) | 0 (0) |
| 26–50 | 16 (14) | 15 (15) | 1 (6) | 18 (29) | 18 (32) | 0 (0) | 9 (28) | 8 (26) | 1 (100) |
| >50 | 5 (4) | 3 (3) | 2 (12) | 14 (22) | 14 (25) | 0 (0) | 19 (59) | 19 (61) | 0 (0) |
| Age group, n (%) | |||||||||
| Adults (≥18 year) | 115 (97) | 98 (97) | 17 (100) | 60 (95) | 54 (95) | 6 (100) | 31 (97) | 31 (100) | 0 (0) |
| Adolescents (12–17) | 0 (0) | 0 (0) | 0 (0) | 2 (3) | 2 (4) | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
| Children (3–11 year) | 2 (2) | 2 (2) | 0 (0) | 1 (2) | 1 (2) | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
| NR | 1 (1) | 1 (1) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 1 (3) | 0 (0) | 1 (100) |
| Sex, mean % male ± SD | 54 ± 27 | 55 ± 26 | 50 ± 32 | 44 ± 25 | 43 ± 23 | 49 ± 42 | 42 ± 21 | 40 ± 18 | 100 ± 0 |
| Baseline health, n (%) | |||||||||
| Healthy | 79 (67) | 67 (66) | 12 (71) | 30 (48) | 26 (46) | 4 (67) | 4 (13) | 4 (13) | 0 (0) |
| Overweight/Obese | 19 (16) | 18 (18) | 1 (6) | 19 (30) | 18 (32) | 1 (17) | 19 (59) | 18 (58) | 1 (100) |
| T1DM | 2 (2) | 1 (1) | 1 (6) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
| T2DM | 18 (15) | 15 (15) | 3 (18) | 5 (8) | 3 (5) | 2 (33) | 4 (12) | 4 (13) | 0 (0) |
| MetS (≥1 criteria) 4 | 8 (7) | 7 (7) | 1 (6) | 20 (32) | 19 (33) | 1 (17) | 15 (47) | 14 (45) | 1 (100) |
| Digestive Issues | 3 (3) | 2 (2) | 1 (6) | 3 (5) | 3 (5) | 0 (0) | 1 (3) | 1 (3) | 0 (0) |
| Region, n (%) | |||||||||
| Europe | 61 (52) | 54 (53) | 7 (41) | 28 (44) | 24 (42) | 4 (67) | 17 (53) | 17 (55) | 0 (0) |
| North America | 36 (31) | 33 (33) | 3 (18) | 21 (33) | 20 (35) | 1 (17) | 8 (25) | 8 (26) | 0 (0) |
| Asia | 12 (10) | 5 (5) | 7 (41) | 10 (16) | 9 (16) | 1 (17) | 6 (19) | 5 (16) | 1 (100) |
| Australia | 6 (5) | 6 (6) | 0 (0) | 3 (5) | 3 (5) | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
| Africa | 2 (2) | 2 (2) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
| South America | 0 (0) | 0 (0) | 0 (0) | 1 (2) | 1 (2) | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
| Multiple | 1 (1) | 1 (1) | 0 (0) | 0 (0) | 0 (0) | 0 (0) | 1 (3) | 1 (3) | 0 (0) |
| Controls 5, n (%) | |||||||||
| Refined grain | 98 (74) | 86 (75) | 12 (67) | 47 (71) | 44 (75) | 3 (43) | 22 (69) | 21 (68) | 1 (100) |
| Usual diet | 0 (0) | 0 (0) | 0 (0) | 2 (3) | 1 (2) | 1 (14) | 5 (16) | 5 (16) | 0 (0) |
| Matched, no WG 6 | 4 (3) | 3 (3) | 1 (6) | 4 (6) | 4 (7) | 0 (0) | 2 (6) | 2 (6) | 0 (0) |
| Other 7/unspecified | 21 (16) | 17 (15) | 4 (22) | 6 (9) | 6 (10) | 0 (0) | 3 (9) | 3 (10) | 0 (0) |
| Crossover of WG only 8 | 10 (8) | 9 (8) | 1 (6) | 4 (6) | 4 (7) | 0 (0) | 0 (0) | 0 (0) | 0 (0) |
| No control arm | 0 (0) | 0 (0) | 0 (0) | 3 (5) | 0 (0) | 3 (43) | 0 (0) | 0 (0) | 0 (0) |
RCT = randomized controlled trial; NR = not reported; SD = standard deviation; MetS = metabolic syndrome; WG = whole grain; 1–3 Other study designs include: 1 crossover, unspecified randomization (n = 14); parallel, unspecified randomization (n = 2); single arm (n = 1); 2 single arm with no control (n = 3) and single arm, with control period (n = 3); 3 unspecified randomization, crossover (n = 1); 4 Have metabolic syndrome or at least one criteria of metabolic syndrome (hyperlipidemia, hypertension, or hyperglycemia); 5 Note that some trials included more than one control arm (total control arms for acute, moderate and long duration trials are n = 133, 66 and 32, respectively); 6 Identical intervention as treatment arm(s) except without whole grain ingredient(s) (e.g., “controlled diet alone,” “yogurt without oats”); 7 Other controls include bran, sucrose and unspecified controls (ex: “placebo”); 8 Crossover studies of different whole grain types, without a non-whole grain arm.