Table 1.
Study characteristics of the RCTs included in the systematic review
| Ref | Lead Author (publication year) |
Location | RCT design | Sample size, (n) |
Male participants, n (%) | Health status of study sample | Mean age, in years (SD)* | Duration | Characteristics of intervention arm | Characteristics of control arm | Overall risk of bias | Isocaloric diet | Different intake or background diet between arms |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| [56] | Abrahamsson et al. (1994) | Sweden | C | 31 | 0 (0) | Healthy female subjects | 26 (6.5) | Two 5-week periods | Oat bran | Wheat bran | SC | – | No |
| [57] | Adamsson et al. (2015) | Sweden | P | 79 | 31 (39.2) | Mildly hypercholesterolemic and overweight subjects | 54.6 (10.8) | 12 weeks | Oat bran (porridge or muesli)—40 g per serving (corresponding to 3 g/d oat β-glucans) | Usual breakfast | SC | – | No |
| [58] | Amundsen ÅL et al. (2003) | Sweden | C | 16 | 9 (56.3) | Hypercholesterolaemic subjects | 57 (7.9) | Two 3-week periods | OβGRE corresponding to 5 g/d oat β -glucans | Diet without OβGREs | SC | Yes | No |
| [59] | Anderson et al. (1990) | USA | P | 14 | 14 (100) | Hypercholesterolemic subjects | 58 | 2 weeks | Oat bran (56 g/d) | Corn flakes (56 g/d) | H | Yes | No |
| [60] | Anderson et al. (1991) | USA | P | 21 | 21 (100) | Hypercholesterolemic male subjects | 61 (2) | 3 weeks | Oat bran as cereal and muffins (110 g/d) | Wheat bran (40 g/d) | SC | Yes | No |
| [61] | Anderson et al. (1984) | USA | P | 20 | 20 (100) | Hypercholesterolemic male subjects | Range (34–66) | 3 weeks | Oat-bran – 100 g/d of oat bran (dry wt.) served as cereals and oat bran muffins | Beans – diet containing 115 g of dried bean (dry wt.) | SC | Yes | No |
| [62] | Ballesteros et al. (2015) | Mexico | C | 29 | 10 (34.5) | Subjects with type 2 diabetes | 53.5 (8.3) | 2 periods of 5 weeks | 40 g/d of oatmeal with 2 cups (472 mL) of lactose-free milk | One egg daily | SC | Yes | No |
| [63] | Beck et al. (2010) | Australia | P | 56 | 0 (0) | Overweight female subjects | 37.4 (5.3) | 12 weeks | 2 MJ energy-deficit diets with high-fibre products with added OβGREs providing β-glucans at a moderate (5–6 g/d) and at a high (8–9 g/d) level | 2 MJ energy-deficit diets with high-fibre products and no oat OβGREs | L | Yes | No |
| [64] | Berg et al. (2003) | Germany | P | 288 | 288 (100) | Male subjects with increased risk for coronary heart disease | 53.6 (6.3) | 4 weeks |
Group 1: fat-modified diet (NCEP step 2) with caloric restriction to 1,000 kcal/d and in addition a daily intake of 35–50 g of oat bran Group 2: fat-modified diet (NCEP step 2) with caloric restriction to 1,000 kcal/d |
Control group: age- and weight-matched normocholesterolemic overweight males; 1,000 kcal/d and only moderately fat-modified diet (NCEP step 1) | SC | No | Yes |
| [65] | Biörklund et al. (2005) | Sweden | P | 89 | 44 (49.4) | Hypercholesteraemic subjects | 18–70 | 5 weeks | Beverage with 5 or 10 g β-glucans extract from oats or barley | Control beverage enriched with rice starch | H | No | Yes |
| [66] | Biörklund et al. (2008) | Sweden | P | 43 | 19 (44.2) | Hyperlipidaemic subjects | 58 (8.2) | 8 weeks | Soup with OβGREs, providing 4 g/d oat β-glucans | Soup without OβGREs | SC | Yes | No |
| [67] | Braaten et al. (1994) | USA | C | 30 | N.R | Hypercholesterolemic subjects | N.R | Two periods of 4 weeks | Oat gum with 2.9 g of β-glucans | Placebo (maltodextrin) | H | Yes | No |
| [68] | Bremer et al. (1991) | New Zealand | C | 12 | 5 (41.7) | Hyperlipidaemic subjects | 53 (10) | 12 weeks | Oat bread—six slices daily for females and 10–12 slices daily for males | Wheat bread—six slices daily for females and 10–12 slices daily for males | SC | Yes | No |
| [69] | Bridges et al. (1992) | USA | P | 20 | 20 (100) | Hypercholesterolemic male subjects | 61 (range 38–73) | 3 weeks | Oat bran 110 g/d (dry wt.), served as a bowl of hot cereal and oat-bran muffins | Wheat-bran diets provided 40 g/d wheat bran (dry wt.) served as a bowl of ready-to-eat cereal and wheat-bran muffins | SC | Yes | No |
| [70] | Chang et al. (2013) | USA | P | 34 | 12 (35.3) | Overweight and obese subjects | 38.5 (11.3) | 12 weeks | β-glucans -containing cereal. One cereal pack (37.5 g) was prescribed to be mixed with 250 mL hot water twice daily | Placebo (cereal without β-glucans) | SC | No | Yes |
| [71] | Chen et al. (2006) | USA | P | 102 | 41 (40) | Healthy subjects | 47.9 (8.4) | 12 weeks | 60 g of oat bran concentrate as a muffin and 84 g of oatmeal squares | 93 g of refined wheat as a muffin and 42 g of corn flakes | L | No | Yes |
| [72] | Connolly et al. (2016) | England | C | 30 | 11 (36.7) | Subjects with glucose intolerance or mild to moderate hypercholesterolemia | 42 (N.R.) | Two 6-week periods | Whole grain oat granola cereal (45 g/d) | Non-whole grain breakfast; 45 g/d | SC | Yes | No |
| [73] | Davy et al. (2002) | USA | P | 36 | 36 (100) | Overweight male subjects | 58 (8.6) | 12 weeks | 60 g oatmeal and 76 g oat bran ready-to-eat cold cereal and the wheat group consumed 5.5 g β-glucans | 60 g whole wheat cereals and 81 g frosted mini-wheats | SC | No | Yes |
| [74] | De Souza et al. (2016) | Brazil | P | 132 | 44 (33.3) | Hypercholesterolemic subjects | 55.8 (10.6) | ~ 13 weeks | 40 g of oat bran | 40 g of corn starch and rice flour | SC | No | Yes |
| [75] | Dubois et al. (1993) | France | P | 6 | 6 (100) | Normolipidemic male subjects | Range (20–27) | 2 weeks | Usual low-fibre diet and oat bran (40 g/d) | Usual low-fibre diet | SC | No | Yes |
| [76] | Ferguson et al. (2020) | Australia | P | 72 | 27 (37.5) | Hypercholesterolemic subjects | 55.1 (1.4) | 6 weeks | Biscuits fortified with 2 g phytosterols (Group 1), 3 g β-glucans (Group 2) and 2 g phytosterols and 3 g β-glucans (Group 3) | Placebo (biscuit without phytosterols and β-glucans) | SC | Yes | No |
| [77] | Geliebter et al., 2014 | USA | P | 36 | 18 (50) | Overweight subjects | 33.9 (7.5) | 4 weeks | Oat porridge or frosted cornflakes | No-breakfast | SC | Yes | No |
| [78] | Gerhardt et al. (1998) | USA | P | 44 | 23 (52.3) | Moderately hypercholesterolemic subjects | 51.7 (1.5) | 6 weeks | Low-fat diet and oat bran; 84 g/d | Low-fat diet and rice starch placebo; 84 g/d | SC | Yes | No |
| [79] | Guevara-Cruz et al. (2012) | Mexico | P | 67 | N.R | Subjects with metabolic syndrome | Range (20–60) | 8 weeks | Habitual diet reduced by 500 kcal and 22 g oats | Placebo: habitual diet reduced by 500 | H | No | Yes |
| [80] | Gulati et al. (2017) | India | P | 69 | N.R | Mildly hypercholesterolemic subjects | 31.2 (6.6) | 4 weeks | 35 g of oats twice daily (total of 70 g/d) in the form of porridge (35 g of oats) for breakfast and a second serving of oats in the form of Upma (35 g of oats) in the afternoon | Usual diet | SC | No | Yes |
| [81] | He et al. (2004) | USA | P | 102 | N.R | Subjects with stage 1 hypertension or increased blood pressure | 47.7 (8.5) | 12 weeks | High fibre: group received a daily serving of 60 g oat bran concentrate as a muffin and 84 g oatmeal squares | Low fibre: 93 g of refined wheat as a muffin and 42 g corn flakes | L | No | Yes |
| [82] | Hegsted et al. (1993) | USA | C | 11 | 10 (90.9) | Mildly hypercholesterolemic subjects | 37 (33.2) | Two periods of 3 weeks | 100 g/d oat bran | 100 g/d stabilized rice bran | SC | Yes | No |
| [83] | Ibrugger et al. (2013) | Denmark | C | 14 | 6 (42.6) | Healthy subjects | 22.9 (2.1) | Four 3-week periods | Beverage of 3.3 g/d oat, barley, and barley mutant b-glucans’ extract of similar molecular mass | Control beverage | SC | Yes | No |
| [84] | Johansson-Persson et al. (2014) | Sweden | C | 30 | 12 (34.3) | Healthy subjects | 58.6 (1.1) | Two 5-week periods | Oat bran beverage combined with a high-fibre diet, providing 4.4 g total dietary fibre per day (corresponding to 2.8 g β-glucans) | The rice beverage in the low-fibre diet provided 0.4 g fibre daily | SC | Yes | No |
| [85] | Kabir et al. (2002) | France | C | 13 | 13 (100) | Subjects with type 2 diabetes | 59 (7.2) | Two 4-week periods | Low-glycaemic index breakfast period, the cereal used was based on extruded oat bran concentrate, apple, and fructose (muesli containing 3 g β-glucans). The bread used was pumpernickel | High-glycaemic index breakfast whole wheat grains and whole meal bread (wheat flour) | SC | Yes | No |
| [86] | Karmally et al. (2005) | USA | P | 152 | 49 (32.2) | Healthy subjects | 49 (10.6) | 11 weeks | Ready-to-eat oat cereal (portion size: 45 g/d) | Corn Cereal | H | No | - |
| [87] | Kashtan et al. (1992) | Canada | P | 84 | 50 (59.5) | Subjects with a history of previous polypectomy and volunteers with normal colon on colonic examination | 55.8 (13) | 2 weeks | Oat bran twice per day (88.4 g/d) | Wheat bran twice per day (73 g/d) | SC | Yes | No |
| [88] | Keenan et al. (1991) | USA | C | 75 | 49 (65.3) | Healthy subjects | Range (20–70) | Three periods of 6 weeks | AHA Step I diet and oat bran, 28 g/d | AHA Step I diet and wheat bran | H | Yes | No |
| [89] | Keenan et al. (2002) | USA | P | 18 | N.R | Hypertensive and hyperinsulinemic subjects | 44 (18) | 6 weeks | Oat cereals providing ~ 5.5 g/d of β-glucans | Low-fibre cereal (< 1 g/d total fibre) | SC | Yes | No |
| [90] | Kerckhoffs et al. (2003) | The Netherlands | P | 48 | 21 (43.8) | Healthy subjects | 53 (13.9) | 4 weeks | Bread and cookies rich in β-glucans (~ 1.5 g/d) from > 5 g/d oat bran | bread and cookies rich in wheat fibre | SC | No | Yes |
| [91] | Kirby et al. (1981) | USA | P | 8 | 8 (100) | Hypercholesterolemic subjects | Range (35–62) | 2 weeks | Diet containing 100 g of oat-bran daily, provided in form of muffins and cereals | Diet composed of commonly available foods | SC | Yes | No |
| [92] | Kristensen et al. (2011) | Denmark | C | 24 | N.R | Healthy subjects | 25.2 (2.7) | Two periods of 2 weeks | Low-fibre diet and 102 g/d oat bran | Low-fibre diet | SC | Yes | No |
| [93] | Laaksonen et al. (2005) | Finland | P | 72 | 36 (50) | Subjects with metabolic syndrome | 55.4 (6.8) | 12 weeks | Oat bread (made of 60% whole meal oat flour and 40% wheat flour) | Rye-pasta | SC | Yes | No |
| [94] | Leadbetter et al. (1991) | USA | P | 40 | 20 (50) | Hypercholesterolemic subjects | Range (25–64) | 4 months | 30, 60 or 90 g/d oat bran | No supplementation | SC | Yes | No |
| [37] | Leão et al. (2019) | Brazil | P | 154 | 41 (26.6) | Subjects with metabolic syndrome | 47.6 (12.6) | 6 weeks | Low-calorie diet plus oat bran (40 g/d) | A low-calorie diet | SC | No | Yes |
| [10] | Li et al. (2016) | China | P | 298 | 155 (52) | Overweight subjects with type 2 diabetes | 59.5 (6) | 4 weeks | Diet with the same quantity of cereals replaced by 50 g and 100 g oats respectively | Low-fat and high-fibre diet | SC | No | - |
| [95] | Liao et al. (2019) | Taiwan | P | 74 | N.R | Healthy and mildly hypercholesterolemic subjects | Range (35–70) | 10 weeks | Oat noodles containing 12 g of β-glucans | Wheat noodles | SC | No | Yes |
| [96] | Liatis et al. (2009) | Greece | P | 41 | 23 (56.1) | Subjects with type 2 diabetes | 62.9 (9.1) | 3 weeks | Bread enriched β-glucans (providing 3 g/d β-glucan) | Bread without β-glucans | H | No | Yes |
| [97] | Liu et al. (2011) | China | P | 120 | 60 (50) | Healthy subjects | N.R | 4 weeks | Either 4 capsules containing 1.6 mg of oat avenanthramides or 8 capsules containing oat avenanthramides-enriched extract (3.1 mg) | Placebo capsules (corn oil) or no treatment at all (control group) | H | No | No |
| [98] | Lovegrove et al. (2000) | UK | P | 62 | 31 (50) | Healthy subjects | 56.6 (9.4) | 8 weeks | 20 g oat bran concentrate providing 3 g β-glucans | 20 g wheat bran | SC | No | No |
| [99] | Maki et al. (2003) | USA | P | 112 | 49 (43.8) | Hypercholesterolemic subjects | 57.3 (9.5) | 6 weeks | Cereal, a snack bar and a beverage with 1.8 g oil–based phytosterols and 2.8 g/d β-glucans | Cereals, a snack bar and a beverage with less than 1 g β-glucans daily, and no oil–based phytosterols | SC | No | Yes |
| [100] | Maki et al., (2007) | USA | P | 60 | 33 (55) | Subjects with elevated blood pressure | 59.7 (9.4) | 12 weeks | A ready-to-eat cold cereal made with oat bran, oatmeal and a powdered form of β-glucans | (1) A low-fibre ready-to-eat cold wheat-based cereal (2) a low-fibre hot cereal and (3) a control maltodextrin powder | SC | No | Yes |
| [101] | Maki et al. (2010) | USA | P | 144 | 31 (21.5) | Healthy subjects | 48.9 (10.2) | 12 weeks | Energy deficit of 500 kcal/d and wholegrain oat cereals containing ~ 3 g/d β-glucans | Energy deficit of 500 kcal/d and low-fibre breakfast/snack foods | SC | No | Yes |
| [102] | Martensson et al. (2005) | Sweden | P | 56 | 24 (42.9) | Moderately hypercholesterolemic subjects | 55 (9) | 3 weeks run-in, 5 weeks intervention | Fermented oat-based product (3–3.5 g/d native β-glucans) and oat-based product ropy which was co-fermented with an exopolysaccharide-producing strain (Pediococcus damnosus) | Fermented dairy-based product | SC | No | – |
| [103] | Missimer et al. (2017) | USA | C | 50 | 24 (48) | Healthy subjects | 23.3 (3.1) | Two periods of 4 weeks | Oatmeal 35 g/d for breakfast | 2 eggs for breakfast, daily | SC | Yes | No |
| [104] | Momenizadeh et al. (2014) | Iran | P | 60 | 21 (35) | Hypercholesterolemic subjects | 51.1 (9.3) | 6 weeks | Five servings of oat bread providing 6 g β-glucans | At least five servings of wheat bread | SC | No | Yes |
| [105] | Noakes et al. (1996) | Australia | C | 23 | 13 (56.5) | Overweight, obese, dyslipidemic and/or hypertensive subjects | 51 (6.7) | Three periods of 4 weeks | Oat bran | Two control diets: high-amylose and low-amylose diet | SC | Yes | No |
| [106] | Önning et al. (1999) | Sweden | C | 66 | 66 (100) | Moderate hypercholesterolemia | Mean age (62.6); Range (52–70) | Two periods of 5 weeks | Oat milk (0.75 L, daily) | Rice milk (0.75 L, daily) | SC | Yes | No |
| [107] | Önning et al. (1998) | Sweden | P | 11 | 6 (54.5) | Healthy, non-smoking subjects | Range (23–54) | 4 weeks | Oat milk daily (0.75 L for females and 1 L for males) | Cow’s milk was a medium-fat milk (0.75 L for females and 1 L for males daily) | SC | Yes | No |
| [20] | Pavadhgul et al. (2019) | Thailand | C | 24 | N.R | Hypercholesterolemic subjects | Range (30–60) | Two 4-week periods | 70 g of instant oat flakes (porridge) | 70 g instant white rice flakes (porridge) | SC | Yes | No |
| [108] | Pins et al. (2002) | USA | P | 88 | 45(51.1) | Subjects with history of essential mild or moderate hypertension | 47.6 (16.1) | Three 4-week periods | 60 g Oatmeal and 77 g Oat Squares | 65 g wheat cereals and 81 g of rice- and corn-based breakfast cereals | SC | No | - |
| [109] | Poulter et al. (1994) | UK | C | 59 | 17 (28.8) | Hypercholesterolemic subjects | 56.3 (2.5) | 2 periods of 4 weeks | Oat-based cereal (50 g) | Usual cereal without oat | SC | Yes | No |
| [22] | Queenan et al. (2007) | USA | P | 75 | 25 (33.3) | Hypercholesterolemic subjects | 44.9 (12.9) | 6 weeks | 6 g/d concentrated β-glucans (powder form) | 6 g/d dextrose monohydrate (powder) | H | - | No |
| [110] | Reyna-Villasmil et al. (2007) | Venezuela | P | 38 | 38 (100) | Mild to moderate hypercholesterolemic subjects | 59.8 (0.6) | 8 weeks | AHA Step II diet plus bread containing 6 g/d of oat-derived β-glucans | Same diet as the intervention arm plus whole-wheat bread providing 6 g/d of fibre | SC | Yes | No |
| [111] | Robitaille et al. (2005) | Canada | P | 34 | 0 (0) | Normal cycling premenopausal overweight female subjects | 38.3 (7.5) | 4 weeks trial (2-week run-in phase) | 28 g/d of oat bran in form of oat bran-enriched muffins | No supplement | SC | No | No |
| [112] | Romero et al. (1998) | Mexico | P | 46 | 46 (100) | Sedentary hypercholesterolemic male subjects | Range (20–45) | 8 weeks | Oat bran–100 g of cookies daily which is equivalent to 2.8 g of soluble fibre derived from oat bran | Wheat bran–100 g of cookies daily which is equivalent to 0.6 g of soluble fibre derived from wheat bran | SC | Yes | No |
| [113] | Saltzman et al. (2001) | USA | P | 43 | 20 (46.5) | Healthy subjects | 44.6 (27.5) | 6 weeks | Hypocaloric diet and oats – 45 g/ (4.2 MJ dietary energy daily) | Hypocaloric diet without oat | SC | No | Yes |
| [114] | Schweinlin et al. (2018) | Germany | P | 36 | 13 (36.1) | Obese subjects with NAFLD | 49.9 (10.3) | 2 + 10 weeks intervention | Powdered diet supplement containing 6 g oatmeal, enriched with 1,7 g β-glucans and 5 g oat fibre–3 × 30 g/d (2 weeks) and 2 × 30 g/d (10 weeks) | Low-glycaemic and insulinemic diet | SC | No | Yes |
| [115] | Tabesh et al. (2014) | Iran | P | 60 | 21(35) | Hypercholesterolemic subjects | 51.1 (9.3) | 4 weeks | Hypocaloric diet with 150 g oat bread rich in β-glucan–corresponding to 18 g/d of β-glucans | Hypocaloric diet with 150 g wheat bread rich in wheat fibre, but no β-glucan | SC | No | Yes |
| [116] | Theuwissen et al. (2009) | The Netherlands | C | 42 | 20 (47.6) | Healthy subjects | 52 (11) | 2 periods of 4 weeks | β-glucan -containing muesli (4.8 g β-glucan) | Muesli without with 4.8 g fibre | SC | Yes | No |
| [117] | Thongoun et al. (2013) | Thailand | C | 24 | 2 (8.3) | Hypercholesterolemic subjects | 51 (6.9) | 2 periods of 4 weeks | Oat bran 70 g (corresponding to 3 g β-gluans) | 70 g rice porridge | SC | Yes | No |
| [23] | Tighe et al. (2010) | UK | P | 206 | 105 (51) | Healthy subjects | 51.8 (7.4) | 12 weeks intervention | 35–40 g whole meal bread plus 60–80 g of whole grain rolled oats daily | 70–80 g whole meal bread plus 30–40 g whole grain cereals or 3 servings of refined cereals foods, daily | SC | No | Yes |
| [118] | Trinidad et al. (2004) | Philippines | C | 21 | 4 (19) | Mildly hypercholesterolemic subjects | 48.4 (4.6) | Four 2-week periods, separated by 2 weeks washout | 50 g organic oat bran flakes daily | 3 comparisons: 50 g corn flakes; 50 g cornflakes with 15% coconut flakes; 50 g 25% coconut flakes | SC | Yes | No |
| [120] | Uusitupa et al. (1992) | Finland | P | 36 | 20 (55.6) | Hypercholesterolemic subjects | 47.8 (7.6) | 8 weeks | 29.8 g oat bran (corresponding to 10.3 g/d β-glucans) | 20.5 g/d wheat bran | SC | - | No |
| [119] | Uusitupa et al. (1997) | Finland | P | 36 | 20 (55.6) | Hypercholesterolemic subjects | 47.8 (7.6) | 8 weeks | 29.8 g oat bran (corresponding to 10.3 g/d β-glucans) | 20.5 g/d wheat bran | H | - | No |
| [121] | Van Horn L et al. (1991) | USA | P | 80 | 40(50) | Hypercholesterolemic subjects | 42.5 (12.9) | 8 weeks | Two packets (56.7 g/d dry wt.) of instant oats | Usual intake | SC | No | - |
| [122] | Vuksan et al. (2017) | Canada | P | 58 | 18 (31) | Overweight and obese subjects with type 2 diabetes | 60 (2) | 26 weeks (6 months) | 25.7 g/d oat bran | 30 g/1000 kcal of ground Salba-chia | SC | No | Yes |
| [123] | Wolever et al. (2010) | Canada | P | 367 | 210 (57.2) | Healthy subjects | 53.5 (9.1) | 4 weeks | Oat bran containing 3–4 g/d β-glucans | Wheat bran | L | No | Yes |
| [124] | Zhang et al. (2012) | China | P | 166 | 65 (39.2) | Subjects with mild to moderate hypercholesterolemia | 53.2 (6.5) | 6 weeks | 100 g/d of instant oat cereal | 100 g/d of wheat flour-based noodles | SC | No | Yes |
N.R. value not reported or could not be found; OβGREs oat beta-glucan-rich extracts; kcal/d kilocalories per day; g/d grams per day NCEP National Cholesterol Education Program; AHA American Heart Association; dry wt. dry weight NAFLD Non-alcoholic fatty liver disease; C cross-over RCT design; P parallel RCT design; H High risk of bias; L Low risk of bias; SC some concerns for bias
*Values are given as mean and (standard deviation) unless otherwise indicated