TABLE 1.
Characteristics of meta-analyses of RCTs included in the umbrella review according to dietary interventions1
| Meta-analyses | Intervention diet | Control diet | n Intervention | n Control | Study population (age ≥ 18 y) | Duration | Quality/risk of bias assessment | Outcomes | Quality of meta-analyses (AMSTAR-2) |
|---|---|---|---|---|---|---|---|---|---|
| LCs | |||||||||
| Nordmann et al. (21) | LC (≤60 g CHO) | LF (≤30% of TE) | 222 | 225 | OW/OB | >6 mo, >12 mo | Criteria set by authors | Weight, TC, LDL-C, HDL-C, TG, SBP, DBP | Critically low |
| Hession et al. (22) | LC/HP2 | HC/LF3 | 375 | 367 | OW/OB | >6 mo, >12 mo | Criteria set by authors | Weight, TC, LDL-C, HDL-C, TG, glucose, SBP, DBP | Critically low |
| Hu et al. (23) | LC (≤45% of TE) | LF (≤30% of TE) | 1396 | 1392 | OW/OB | 6–24 mo | No | Weight, TC, LDL-C, HDL-C, TG, glucose, insulin, SBP, DBP | Critically low |
| Santos et al. (24) | LC4 | Other | 2394 | 4346 | OB | 3–24 mo | Criteria set by authors | Weight, BMI, LDL-C, HDL-C, TG, glucose, insulin, HbA1c, SBP, DBP | Critically low |
| Ajala et al. (25) | LC4 | Other | NA | NA | T2DM | 6–12 mo | Cochrane RoB | HbA1c | Critically low |
| Bueno et al. (26) | VLCKD (≤50 g CHO or ≤10% of TE) | LF (≤30% of TE) | 712 | 703 | OW/OB | 12–24 mo | Cochrane RoB | Weight, LDL-C, HDL-C, TG, SBP, DBP | High |
| Naude et al. (27) | LC4 | Balanced energy-restricted diets | 837 | 872 | OW/OB, T2DM | 3–6 mo, 12–24 mo | Cochrane RoB | Weight | Moderate |
| Alexandraki et al. (28) | LC (≤45% of TE) | LF (≤30% of TE) | 1548 | 1543 | OW/OB | 6 mo, 12 mo | Cochrane RoB | Weight | Critically low |
| Sackner-Bernstein et al. (29) | LC (≤120 g CHO) | LF (≤30% of TE) | 895 | 902 | OW/OB | 2–24 mo | No | Weight | Critically low |
| Fan et al. (30) | LC (≤130 g CHO) | Other | 567 | 569 | T2DM | 3–48 mo | Jadad scale | Weight, HbA1c | Critically low |
| Hashimoto et al. (31) | LC4 | Other | 697 | 719 | OW/OB | 2–24 mo | AMSTAR | Weight | Critically low |
| Mansoor et al. (7) | LC (≤20% of TE) | LF (≤30% of TE) | 688 | 681 | OW/OB | 6–24 mo | Cochrane RoB | Weight, TC, LDL-C, HDL-C, TG, glucose, insulin, SBP, DBP | High |
| Steckhan et al. (32) | LC4 | Other | 96 | 90 | MetS | 1–24 mo | Cochrane RoB | Weight, insulin | Low |
| Meng et al. (33) | LC (≤26% of TE) or ≤130 g CHO/d | HC (45–60% of TE) | 366 | 368 | T2DM | 3–24 mo | Jadad scale | Weight, TC, LDL-C, HDL-C, TG, glucose, HbA1c | Critically low |
| Snorgaard et al. (34) | LC (≤45% of TE) | HC (45–60% of TE) | 414 | 425 | T2DM | <12 mo, ≥12 mo | Cochrane RoB | Weight, BMI, LDL-C, HbA1c | Critically low |
| Huntriss et al. (35) | LC4 | Other | 330 | 315 | T2DM | 12 mo | Cochrane RoB | Weight, TC, LDL-C, HDL-C, TG, HbA1c, SBP, DBP | Critically low |
| Sainsbury et al. (36) | LC (≤45% of TE) | HC (>45% of TE) | NA | NA | T2DM | 6 mo, 12 mo | Cochrane RoB | Weight, HbA1c | Moderate |
| van Zuuren et al. (37) | LC (≤40% of TE) | LF (≤30% of TE) | 269 | 270 | T2DM | <2 mo, 2–4 mo, 4–6 mo, >6 mo, 24 mo | Cochrane RoB/ROBINS-I tool | Weight, BMI, LDL-C, HDL-C, TG, glucose, HbA1c, SBP, DBP | Moderate |
| Gjuladin-Hellon et al. (38) | LC (≤45% of TE) | LF (≤35% of TE) | 1680 | 1678 | OW/OB | 6–24 mo | Cochrane RoB | TC, LDL-C, HDL-C, TG | Critically low |
| Korsmo-Haugen et al. (39) | LC (≤40% of TE) | HC (>40% of TE) | 15875 | NA | T2DM | 3–24 mo | Cochrane RoB | Weight, TC, LDL-C, HDL-C, TG, HbA1c, SBP, DBP | High |
| McArdle et al. (40) | LC4 | Other | 1006 | 1126 | T2DM | 3–52 mo | Cochrane RoB | Weight, HbA1c | Critically low |
| HPs | |||||||||
| Santesso et al. (8) | HP4 | LP | 1158 | 1160 | Different health status | >1 mo | No | Weight, BMI, TC, LDL-C, HDL-C, TG, glucose, insulin, HbA1c, SBP, DBP | Critically low |
| Wycherley et al. (41) | HP (25–35% of TE) | LP (12–18% of TE) | 494 | 516 | Different health status | 1–13 mo | Cochrane RoB | Weight, TC, LDL-C, HDL-C, TG, glucose, insulin, SBP, DBP | Critically low |
| Ajala et al. (25) | HP44 | Other | 72 | 65 | T2DM | 6–12 mo | Cochrane RoB | HbA1c | Critically low |
| Dong et al. (42) | HP (>20% of TE) | LP (15–20% of TE) | NA | NA | T2DM | 1–6 mo | Criteria set by authors | Weight, TC, LDL-C, HDL-C, TG, glucose, HbA1c, SBP, DBP | Critically low |
| Schwingshackl and Hoffmann (43) | HP (≥25% of TE) | LP (≤20% of TE) | 533 | 599 | Different health status | 12–24 mo | Cochrane RoB/Jadad scale | Weight, TC, LDL-C, HDL-C, TG, glucose, insulin, HbA1c, SBP, DBP | Critically low |
| Clifton et al. (44) | HP4 | LCD | 1681 | 1811 | Different health status | 13–52 mo | Cochrane RoB | Weight, TC, LDL-C, HDL-C, TG, glucose, insulin, HbA1c, SBP, DBP | Critically low |
| Johansson et al. (45) | HP (25–30% of TE) | Other | 451 | 414 | Different health status | 0.8–2 mo | Criteria set by authors | Weight | Critically low |
| Zhao et al. (46) | HP4 | LP | 520 | 539 | T2DM | 1–24 mo | Cochrane RoB | Weight, BMI, TC, LDL-C, HDL-C, TG, glucose, insulin, HbA1c, SBP, DBP | Critically low |
| LFs | |||||||||
| Astrup et al. (47) | Reduced fat4 | Other | 1101 | 869 | Nondiabetic | 2–12 mo | No | Weight | Critically low |
| Avenell et al. (48) | LF4 | Other | 665 | 688 | OW/OB | 12 mo | Criteria set by authors | Weight | Critically low |
| Schwingshackl and Hoffmann (49) | LF (≤30% of TE) | Other, HF (>30% of TE), LC (<50 g CHO), LGI/LGL, MUFA | 3793 | 4249 | OW/OB | >3 mo | Cochrane RoB/Jadad scale | TC, LDL-C, HDL-C, TG | Critically low |
| Wu et al. (50) | LF (≤30% of TE) | Usual diet | 900 | 636 | Women | 1–12 mo | Jadad scale | TC, LDL-C, HDL-C, TG | Critically low |
| Boaz et al. (51) | LF (≤30% of TE) | LC (≤45% of TE) | 569 | 592 | OW/OB | 1–8.7 y | No | Weight | Critically low |
| Hooper et al. (52) | LF (≤30% of TE) | HF (>30% of TE) | 22,316 | 31,331 | Different health status | 0.5–8 y | Cochrane RoB | Weight, BMI, TC, LDL-C, HDL-C, TG, SBP, DBP | High |
| Tobias et al. (53) | LF4 | Other, HF, LC, usual diet | NA | NA | Different health status | 1–10 y | Cochrane RoB | Weight | Low |
| Steckhan et al. (32) | LF4 | Other | 116 | 111 | MetS | 1–24 mo | Cochrane RoB | Weight | Low |
| Lu et al. (54) | LF (≤30% of TE) | HF (>30% of TE) | NA | NA | OW/OB | 2–24 mo | Cochrane RoB/Jadad scale | TC, LDL-C, HDL-C, TG, SBP, DBP | Low |
| Paleolithic diet | |||||||||
| Manheimer et al. (55) | Paleolithic | Other | 73 | 64 | MetS | 0.5–6 mo | Cochrane RoB | HDL-C, TG, glucose, SBP, DBP | Low |
| Ghaedi et al. (56) | Paleolithic | Other | 115 | 98 | Different health status | 0.5–24 mo | Cochrane RoB | Weight, BMI, TC, LDL-C, HDL-C, TG, SBP, DBP | Low |
| LGI/LGLs | |||||||||
| Opperman et al. (57) | LGI4 | HGI | 206 | 200 | Different health status, T2DM | <6 mo | Criteria adapted from the Cochrane EPOC Group | TC, LDL-C, HDL-C, TG, HbA1c | Critically low |
| Thomas et al. (58) | LGI/LGL4 | HGI/HGL | 82 | 81 | OW/OB | 1.3–6 mo | Criteria set by authors | Weight, BMI, TC, HDL-C, TG, glucose, insulin | High |
| Thomas and Elliott (59) | LGI4 | HGI | 238 | 219 | T2DM | 1–6 mo | Criteria set by authors | HbA1c | Critically low |
| Ajala et al. (25) | LGI/LGL4 | Other | 181 | 172 | T2DM | 6–12 mo | Cochrane RoB | HbA1c | Critically low |
| Fleming and Godwin (60) | LGI4 | HGI | 107 | 105 | OW/OB | <3 mo | US Preventive Services Task Force Quality Rating Criteria | TC, LDL-C, HDL-C, TG | Critically low |
| Goff et al. (61) | LGI4 | HGI | 733 | 679 | Different health status, T2DM | >1 mo | Jadad scale | TC, LDL-C, HDL-C, TG | Low |
| Schwingshackl and Hoffmann (62) | LGI/LGL4 | HGI/HGL | 913 | 857 | Different health status | 6–17 mo | Cochrane RoB | Weight, TC, LDL-C, HDL-C, TG, glucose, insulin, HbA1c, SBP, DBP | Critically low |
| Wang et al. (63) | LGI4 | HGI | 421 | 409 | T2DM | <36 mo | Jadad scale | HbA1c | Critically low |
| Clar et al. (64) | LGI4 | HGI | NA | NA | CVD | >3 mo | Cochrane RoB | Weight, BMI, TC, LDL-C, HDL-C, TG, SBP, DBP | High |
| Evans et al. (65) | LGI/LGL4 | HGI/HGL | NA | NA | Healthy adults | <18 mo | Cochrane RoB | SBP, DBP | Low |
| Ojo et al. (66) | LGI4 | HGI | 291 | 283 | T2DM | <22 mo | Cochrane RoB/CASP RCT Checklist | Glucose, HbA1c | Critically low |
| Zafar et al. (67) | LGI4 | Other | 3333 | 3241 | OW/OB | <26 mo | Cochrane RoB | Weight, BMI, TC, LDL-C, HDL-C, TG, glucose | Low |
| IER | |||||||||
| Alhamdan et al. (68) | ADF | VLCD | 915 | NA | OW/OB | 2–3 mo | Downs and Black checklist | Weight | Critically low |
| Headland et al. (69) | IER | CER | 230 | 216 | Different health status | >12 mo | Cochrane RoB | Weight | Critically low |
| Cioffi et al. (70) | IER6 | CER | 343 | 222 | Different health status | 2–6 mo | Cochrane RoB | Weight, TC, LDL-C, HDL-C, TG, glucose, insulin, HbA1c, SBP, DBP | Critically low |
| Harris et al. (71) | IER7 | Ad libitum/CER8 | 180 | 137 | OW/OB | 3–12 mo | Cochrane RoB | Weight | Moderate |
| Harris et al. (72) | IER7 | Ad libitum/CER8 | 161 | 126 | OW/OB | 3 mo | JBI SUMARI | Weight, TC, LDL-C, HDL-C, TG, glucose, insulin | Critically low |
| Roman et al. (73) | IER | CER | 329 | 337 | OW/OB | 3–13 mo | Cochrane RoB | Weight | Critically low |
| MDs | |||||||||
| Esposito et al. (74) | MD | Other | 1937 | 1588 | Different health status | 1–60 mo | Jadad scale | Weight, BMI | Critically low |
| Kastorini et al. (75) | MD | Other | 2202 | 1903 | OW/OB | 1–48 mo | Criteria set by authors | HDL-C, TG, glucose, SBP, DBP | Critically low |
| Nordmann et al. (76) | MD | LF (≤30% of TE) | 1641 | 1009 | OW/OB | 24 mo | Criteria set by authors | Weight, BMI, TC, LDL-C, HDL-C, glucose, insulin, SBP, DBP | Critically low |
| Ajala et al. (25) | MD | Other | 308 | 280 | T2DM | 6–12 mo | Cochrane RoB | HbA1c | Critically low |
| Huo et al. (77) | MD | Other | 568 | 521 | T2DM | 1–48 mo | Cochrane RoB | Weight, BMI, TC, LDL-C, HDL-C, TG, glucose, insulin, HbA1c, SBP, DBP | Critically low |
| Esposito et al. (78) | MD | Other | 395 | 278 | Different health status | 1–60 mo | Cochrane RoB | HbA1c | Low |
| Garcia et al. (79) | MD | Other | 32625 | NA | Different health status | 1–52 mo | Cochrane RoB | HDL-C, TG, glucose, SBP, DBP | Low |
| Gay et al. (80) | MD | Other | 5148 | 5013 | Different health status | 6–48 mo | Cochrane RoB | SBP, DBP | Critically low |
| Ndanuko et al. (81) | MD | Other | 310 | 225 | Different health status | 2–24 mo | Cochrane RoB | SBP, DBP | Critically low |
| Nissensohn et al. (82) | MD | Other | 5226 | 5111 | OW/OB | 24 mo | Cochrane RoB | SBP, DBP | Critically low |
| Rees et al. (9) | MD | Other | 692 | 662 | Primary/secondary prevention | ≥3 mo | Cochrane RoB | TC, LDL-C, HDL-C, TG, SBP, DBP | High |
| Nordic diet | |||||||||
| Ndanuko et al. (81) | Nordic | Other | 306 | NA | Different health status | 2–24 mo | Cochrane RoB | SBP, DBP | Critically low |
| Ramezani-Jolfaie et al. (83) | Nordic | Typical/Danish diets | 5135 | NA | Different health status | 0.5–6 mo | Cochrane RoB | TC, LDL-C, HDL-C, TG, SBP, DBP | High |
| VGTs | |||||||||
| Yokoyama et al. (84) | VGT, LOV | Non-VGT | 210 | 195 | Different health status | 1.5–13 mo | No | SBP, DBP | Critically low |
| Yokoyama et al. (85) | VGT | Non-VGT | 120 | 174 | T2DM | 1–18.5 mo | Cochrane RoB | Glucose, HbA1c | Critically low |
| Barnard et al. (86) | VGT | Non-VGT | 6895 | NA | Different health status | 3–26 mo | Cochrane RoB | Weight | Low |
| Huang et al. (87) | VGT, LOV, VGN | Non-VGT | 11515 | NA | Different health status | 2.3–24 mo | Jadad scale | Weight | Critically low |
| Wang et al. (88) | VGT, LOV, VGN | Non-VGT | 7855 | NA | Different health status | 2.3–24 mo | Cochrane RoB | Weight, TC, LDL-C, HDL-C, TG | Critically low |
| Yokoyama et al. (89) | VGT | Non-VGT | 13295 | NA | Different health status | >1.5 mo | Jadad scale | TC, LDL-C, HDL-C, TG | Critically low |
| Picasso et al. (90) | VGT | Non-VGT | 350 | 339 | Different health status | 1.5–18.5 mo | Cochrane RoB | HDL-C, TG, glucose, SBP, DBP | Low |
| Viguiliouk et al. (91) | VGT | Non-VGT | 329 | 337 | T2DM | 1–18.5 mo | Cochrane RoB | Weight, BMI, LDL-C, HDL-C, TG, glucose, HbA1c, SBP, DBP | Moderate |
| Lopez et al. (92) | VGN | Non-VGN | 10785 | NA | Different health status | 0.8–18.5 mo | Cochrane RoB | SBP, DBP | High |
| DASH diet | |||||||||
| Shirani et al. (93) | DASH | Other | 815 | 813 | Different health status | 0.8–6 mo | No | Glucose, insulin | Critically low |
| Saneei et al. (94) | DASH | Other | 1281 | 1280 | Different health status | 0.5–6.5 mo | Criteria set by authors | SBP, DBP | Critically low |
| Siervo et al. (95) | DASH | Other | 964 | 964 | Different health status | 0.5–6 mo | Jadad scale | TC, LDL-C, HDL-C, TG, glucose, SBP, DBP | Critically low |
| Gay et al. (80) | DASH | Other | NA | NA | Different health status | 6–48 mo | Cochrane RoB | SBP, DBP | Critically low |
| Ndanuko et al. (81) | DASH | Other | 1399 | 1399 | Different health status | 2–24 mo | Cochrane RoB | SBP, DBP | Critically low |
| Soltani et al. (96) | DASH | LCD | 1291 | 1291 | Different health status | 2–13 mo | Cochrane RoB | Weight, BMI | Low |
| Portfolio dietary pattern9 | |||||||||
| Chiavaroli et al. (97) | Portfolio | Energy-matched diets | 4395 | NA | Dyslipidemia | 1–6 mo | Cochrane RoB | Weight, TC, LDL-C, HDL-C, TG, SBP, DBP | High |
1
ADF, alternate day fasting; AMSTAR, A MeaSurement Tool to Assess systematic Reviews; CASP, Critical Appraisal Skills Programme; CER, continuous energy restriction; CHO, carbohydrates; Cochrane RoB, the Cochrane risk-of-bias tool for randomized trials; CVD, cardiovascular disease; DASH, Dietary Approaches to Stop Hypertension; DBP, diastolic blood pressure; EPOC, Effective Practice and Organisation of Care; HbA1c, glycated hemoglobin; HC, high-carbohydrate diet; HDL-C, HDL cholesterol; HF, high-fat diet; HGI, high-glycemic-index; HGL, high-glycemic-load; HP, high-protein diet; IER, intermittent energy restriction; JBI SUMARI, Joanna Briggs Institute's System for the Unified Management, Assessment, and Review of Information critical appraisal tool; LC, low-carbohydrate diet; LCD, low-calorie diet; LDL-C, LDL cholesterol; LF, low-fat diet; LGI/LGL, low-glycemic-index/low-glycemic-load diet (total fat >30% of daily energy consumption, CHO <50% of daily energy consumption, and low-glycemic-index foods); LOV, lacto-ovo-vegetarian diet; LP, low-protein diet; MD, Mediterranean diet; MetS, metabolic syndrome; MUFA, high-MUFA diet (total fat >30% of daily energy consumption and MUFA >12% of daily energy consumption); NA, not available; OB, obese; OW, overweight; RCT, randomized controlled trial; ROBINS-I, Risk of Bias In Non-randomized Studies of Interventions; SBP, systolic blood pressure; TC, total cholesterol; TE, total energy; TG, triglyceride; T2DM, type 2 diabetes mellitus; VGN, vegan diet; VGT, vegetarian diet; VLCD, very-low-calorie dieting (<800 kcal/d); VLCKD, very-low-carbohydrate ketogenic diets (≤50 g/d of CHO or ≤10% of daily energy from CHO).
2
Low-carbohydrate (≤60 g/d of CHO)/ketogenic diets (<40 g/d of CHO).
3
Low-fat (≤30% of daily energy from fat)/high-carbohydrate conventional diets, energy restricted.
4
As defined by the investigators of each trial.
5
Number of total participants.
6
IER defined as 75% energy restriction on “fast” days, with a maximum cutoff of 500 and 660 kcal/d for females and males, respectively.
7
IER defined as consumption of ≤800 kcal on ≥1 d, but no more than 6 d in 1 wk.
8
Control defined as “ad libitum” diet (no intervention) or advice to continuously follow a reduced-calorie diet of ∼25% of estimated daily energy requirements.
9
Portfolio dietary pattern was defined as including the following components: 1–3 g plant sterols/d, 15–25 g viscous fibers/d (from oats, barley, psyllium, legumes, eggplants, and okra), 35–50 g plant protein/d, and 25–50 g nuts/d.