Table 1.
Characteristics of included randomized controlled trials.
| Study, Year (References) | Participants | Age *, Year | Body Weight or BMI *,† | Diabetes Duration *, Year | Setting ‡ | Design | Feeding Control § | PP Type || | AP Type || | Amount of AP Replaced ¶ | Food Form ††† | Diet # | Energy Balance | Follow-up | MQS ** | Funding Sources †† |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| TYPE 2 DIABETES | ||||||||||||||||
| Anderson et al. 1998 [29] ‡‡ | 8 T2D+N, O, HT (M only) | 68 (18.4) | 111 (66.8) kg | >5 | OP, USA | C | Supp | 50% (~55.5 g/day) | Whole | Neutral | 8 wk | 8 | NA | |||
| Intervention | Soy | ~15:55:30 | ||||||||||||||
| Control | Mixed | ~15:55:30 | ||||||||||||||
| Hermansen et al. 2001 [16] §§ | 20 T2D+R (6W, 14M) | 63.6 (7.5) | 3 (2.7) | OP, DNK | C | Supp | ~33% (50 g/day) | Powder | Neutral | 6 wk | 5 | Agency-industry | ||||
| Intervention | 88.7 (11.9) kg | Soy | 25:41:29 | |||||||||||||
| Control | 88.3 (11.8) kg | Casein | 26:43:28 | |||||||||||||
| Wheeler et al. 2002 [15] |||| | 17 T2D+N (3W, 14M) | 56 (12.4) | 102.3 (21.4) kg | 7 (1–16) | OP, USA | C | Met | 60% (64 g/day) | Whole | Neutral | 6 wk | 6 | Agency-industry | |||
| Intervention | Mixed | 17:53:30 | ||||||||||||||
| Control | Mixed | 17:53:30 | ||||||||||||||
| Azadbakht et al. 2008 [13] ¶¶ | 41 T2D+N,R (23W, 18M) | 10 (3) | OP, IRN | P | Supp | 35% (~20 g/day) | Whole | Neutral | 4 y | 4 | NA | |||||
| Intervention | 61.9 (11.8) | 71 (9) kg | Soy | ~10:70:20 | ||||||||||||
| Control | 62.1 (12.1) | 72 (8) kg | Mixed | ~10:68:22 | ||||||||||||
| Azadbakht et al. 2009 [31] ## | 14 T2D+N (4W, 10M) | 62.5 (12.1) | 10 (4) | OP, IRN | C | Supp | 35% (~20 g/day) | Whole | Neutral | 7 wk | 4 | Agency | ||||
| Intervention | 70.6 (10.3) kg | Soy | ~9:70:21 | |||||||||||||
| Control | 70.7 (10.7) kg | Mixed | ~9:69:22 | |||||||||||||
| Gobert et al. 2010 [32] *** | 29 T2D (13W, 16M) | 60.1 (9.64) | 83.4 (10.9) kg | 3.4 (4.8) | OP, CAN | C | Supp | ~34% (40 g/day) | Powder | Neutral | 8 wk | 7 | Agency-industry | |||
| Intervention | Soy | ~23:45:32 | ||||||||||||||
| Control | Milk | ~23:44:33 | ||||||||||||||
| Cohen et al. 2011 [30] ‡‡‡ | 13 T2D (6W, 7M) | At least 1 year | OP, USA | P | Supp | NA (~6 g/day) | Whole | NA | Neutral | 12 wk | 7 | Agency | ||||
| Intervention | 66 (8.1) | 96.1 (21.8) kg | Almonds | |||||||||||||
| Control | 66 (8.7) | 105.1 (29.6) kg | Cheese | |||||||||||||
| Miraghajani et al. 2013 [24] §§§ | 25 T2D+N (15W, 10M) | 51 (10) | NA | OP, IRN | C | DA | ~4% (2.5 g/day) | Whole | Neutral | 4 wk | 6 | Agency | ||||
| Intervention | 76.1 (13.2) kg | Soy | 14:46:40 | |||||||||||||
| Control | 76.5 (13.6) kg | Milk | 13:50:37 | |||||||||||||
| Abd-Mishani et al. 2014 [33] ||||||| | 21 T2D (18W, 6M) | 61.7 (6) | 74.5 (7.1) kg | 3.4 (1.2) | OP, IRN | C | DA | ~18% (~13.3 g/day) | Whole | Neutral | 8 wk | 4 | Agency | |||
| Intervention | Pulses | 15:55:30 | ||||||||||||||
| Control | Red meat | 15:55:30 | ||||||||||||||
| Hosseinpour-Niazi et al. 2014 [14] ||||||| | 31 T2D+O (24W, 7M) | 58.1 (33.4) | NA | OP, IRN | C | DA | ~17% (~13.3 g/day) | Whole | Neutral | 8 wk | 6 | Agency | ||||
| Intervention | 27.7 (3.34) kg/m2 | Pulses | 14:54:33 | |||||||||||||
| Control | 27.8 (3.34) kg/m2 | Red meat | 15:52:34 | |||||||||||||
| Markova et al. 2015 [23] ¶¶¶ | 37 T2D (13W, 24M) | NA | OP, DEU | P | Supp | ~32.5% (NA) | Both | Neutral | 6 wk | NA | NA | |||||
| Intervention | 63.7 (6.54) | 86 (13.9) kg | Pulses | 30:40:30 | ||||||||||||
| Control | 65 (5.9) | 92.6 (11.9) kg | Mixed | 30:40:30 | ||||||||||||
| TYPE 1 DIABETES | ||||||||||||||||
| Kontessis et al. 1995 [27] ### | 9 T1D (7W, 2M) | 32 (20–48) **** | 23.8 (20.6–27.8) kg/m2 **** | Onset before the age of 30 | OP, GRC | C | NA | 70% (~49 g/day) | Whole | Neutral | 4 wk | 7 | NA | |||
| Intervention | Mixed | ~17:49:34 | ||||||||||||||
| Control | Mixed | ~19:41:37 | ||||||||||||||
| Stephenson et al, 2005 [28] | 12 T1D+GHF (6W, 6M) | 29.9 (8) | 79.0 (5.9) kg | 15.1 (8) | OP, USA | C | Supp | ~46%–56% (45–55 g/day) | Whole | Neutral | 8 wk | 5 | Agency-industry | |||
| Intervention | Soy †††† | 22:53:27 | ||||||||||||||
| Control | Mixed | 16:49:36 |
AP = animal protein; BW = body weight; C = crossover; CAN = Canada; DA = dietary advice; DEU = Germany; DNK = Denmark; GHF = glomerular hyperfiltration; GRC = Greece; HT = hypertension; IRN = Iran; M = men; Met = metabolic feeding control; MQS = Heyland Methodological Quality Score; N = nephropathy; NA = data not available; O = overweight and/or obese; P = parallel; PP = plant protein; R = retinopathy; Supp = supplemental feeding control; T1D = type 1 diabetes; T2D = type 2 diabetes; USA = United States of America; W = women; wk = weeks; y = years; * Age, body weight or BMI, and diabetes duration are reported as mean ± SD or range; † Baseline body weight (kg) values. Baseline BMI values (kg/m2) are only reported when no data on body weight were available; ‡ Countries are abbreviated using three letter country codes (ISO 3166-1 alpha-3 codes); § Metabolic feeding control (Met) is the provision of all meals, snacks, and study supplements consumed during the study under controlled conditions. Supplement feeding control (Supp) is the provision of study supplements only. Dietary advice (DA) is the provision of counselling on the appropriate test and control diets; || Plant and animal protein types refer to the specific sources of plant proteins prescribed by the study to replace a specific source(s) of animal protein. If the prescribed plant or animal protein type was not specified by the study it was assumed that the protein type consisted of mixed sources. For example, Kontessis et al. [27] referred to their intervention arm as a “vegetable protein diet” and their control arm as an “animal protein diet”; therefore it was assumed that the intervention and control arm consisted of mixed sources of plant and animal protein, respectively; ¶ Data in this column represents the amount of plant protein that was prescribed by the study to replace animal protein. Numbers not in parentheses represent the percentage of total protein replacing animal protein with plant protein. Numbers in parentheses represent the amount of plant protein prescribed/amount of animal protein replaced in grams per day. Numbers preceded by “~” were calculated using relevant data provided by the study. All studies partially replaced animal protein with plant protein with the exception of Wheeler et al. [15] and Kontessis et al. [27], which fully replaced animal protein with plant protein sources; # Data in this column indicates the designed percent energy breakdown from protein:carbohydrate:fat reported from each study. If these values were not available or provided, the measured percent energy breakdown from the end of the study were provided. Numbers preceded by “~” were calculated using relevant data provided by the study; ** Trials with a MQS score ≥ 8 were considered to be of higher quality; †† Agency funding consists of funding from government, university, or not-for-profit health agency sources. None of the trialists declared any conflicts of interest with the exception of Stephenson et al. [28] and Hermansen et al. [16]; ‡‡ Both intervention and control arm were designed to contain 1 gram of protein per kilogram body weight per day. Fifty percent of the protein in the soy protein intervention arm was in the form of beverages, meat analogue patties, or ground meat analogues, whereas 50% of the protein in the animal protein control arm was in the form of ground beef with a specified fat content and cow milk; §§ Both intervention and control arm were provided with their respective powders and instructed to mix half of their daily allotted amount in 250ml of water before breakfast and half before their evening meal. The powder provided in the intervention arm also contained 20 g/day of soy cotyledon fibre and a high isoflavone content (minimum 165 mg/day), whereas the powder provided in the control arm contained 20 g/day of cellulose; |||| The intervention arm consisted exclusively of plant protein (62% soy-based), where major protein foods included tofu, textured vegetable protein, soy milk, and legumes. The control arm consisted of 60% animal protein and 40% plant protein, where major protein foods included beef, poultry, fish and milk; ¶¶ 73% of participants in this study had retinopathy. Both intervention and control arm were designed to contain 0.8 grams of protein per kilogram body weight per day. The intervention arm consisted of 35% soy protein (in the form of textured soy protein), 30% other plant protein and 35% animal protein, whereas the control arm consisted of 70% animal protein and 30% plant protein; ## The intervention arm consisted of 35% soy protein (in the form of textured soy protein), 30% other plant protein and 35% animal protein and the control arm consisted of 70% animal protein and 30% plant protein;*** Women in this study were postmenopausal. The powder provided in the intervention arm also consisted of 88 mg/day isoflavones (65% genistein, 31% daidzein, 4% glycitein). Participants supplemented their habitual diets with the powders and were provided with multiple examples of ways to consume them but were encouraged to reconstitute them with water with the option of adding Nestle flavour packets. In order to avoid excess protein and calcium intakes, participants were counselled to replace foods like milk, cheese, and lunchmeat with the powders; ††† Food form refers to whether the test foods in each study were in the form of whole foods (whole), isolated protein powders (powder), or both; ‡‡‡ Participants were instructed to consume their food prescription (1 oz almonds or 2 cheese sticks) 5 days per week; §§§ Both intervention and control arm were designed to contain 0.8 grams of protein per kilogram body weight per day. The intervention and control arm consisted of 1 glass of soy and cow’s milk (240 mL each) per day, respectively; ||||||| Both intervention and control arm were prescribed a Therapeutic Lifestyle Change (TLC) diet. The intervention arm was the same as the control arm but participants were advised to replace 2 servings of red meat with different types of cooked legumes such as lentils, chickpeas, peas and beans 3 days per week. Half a cup of cooked legumes was considered to be one serving of red meat; ¶¶¶ The intervention arm received foods enriched with pea protein (i.e., mash powder, bread, pancake powder, noodles). The control arm contained dairy products and meat in larger quantities to achieve 30% of energy from protein; ### Both intervention and control arm were designed to contain 1 gram of protein per kilogram body weight per day. Intervention arm consisted of plant protein exclusively and the control arm consisted of ~70% animal protein and 30% plant protein. The intervention arm was also provided animal fat supplements, as well as calcium and phosphate tablets; **** Reported as a median value; †††† Nine daily soy food intake options were provided: soy patties; soy pasta; soy chocolate beverage; chocolate, vanilla, or plain silk soy milk; lemon or chocolate soy bars; roasted soy nuts, or frozen edamame.