Tighe 2010‐W.
Study characteristics | ||
Methods |
Setting: UK (Aberdeen, Scotland) Design: parallel‐group RCT, stratified by sex, age, and BMI Dates: September 2005 to December 2008 Intervention duration: 12 weeks (following 4‐week run‐in) Follow‐up: no postintervention follow‐up Focus: to assess the effects of consumption of 3 daily portions of whole grains (2 intervention groups: wheat only or a mixture of wheat and oats) compared to refined grains on markers of cardiovascular disease risk in people at relatively high risk. |
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Participants |
N: 226 randomised (73/77 completers in the whole grain wheat intervention group; 70/73 in the whole grain wheat and oats group; and 63/76 in the control group). Inclusion criteria: male and female, aged 40 to 65 years with a BMI between 18.5 and 35. Sedentary or moderately active (< 2 aerobic sessions/wk) people or those with signs of metabolic syndrome or moderate hypercholesterolaemia. Exclusion criteria: people with CVD, diabetes, fasting blood glucose > 7.0 mmol/L, asthma, systolic BP > 160 mmHg and diastolic BP > 99 mmHg, thyroid conditions, eating disorders, high intake of whole grain foods, or taking regular medication or supplements known to affect any of the outcomes. Age (years): 40 to 65 years recruited: whole grain wheat group mean age 51.6 (SEM 0.8); whole grain wheat + oats: 52.1 (SEM 0.9); refined grain (control group): 51.8 (SEM 0.8). Sex (% men): whole grain wheat group: 52%; whole grain wheat + oats: 51%; refined grain (control group): 48%. Ethnicity: Scottish (ethnic composition not reported) Baseline cardiovascular risk status: BMI (kg/m2): whole grain wheat group: 28.0 (SEM 0.5); whole grain wheat + oats: 27.0 (SEM 0.4); control: 28.0 (SEM 0.5); P = 0.221 Total cholesterol (mmol/L): whole grain wheat group: 5.46 (SEM 0.14); whole grain wheat + oats: 5.57 (SEM 0.12); control: 5.94 (SEM 0.14); P = 0.087 HDL cholesterol (mmol/L): whole grain wheat group: 1.55 (SEM 0.04); whole grain wheat + oats: 1.62 (SEM 0.05); control: 1.62 (SEM 0.06); P = 0.506 LDL cholesterol (mmol/L): whole grain wheat group: 3.45 (SEM 0.11); whole grain wheat + oats: 3.45 (SEM 0.11); control: 3.66 (SEM 0.12); P = 0.365 Triglycerides (TAG): whole grain wheat group: 1.27 (SEM 0.08); whole grain wheat + oats: 2 (SEM 0.06); control: 1.49 (SEM 0.11); P = 0.012 Systolic blood pressure (mmHg): whole grain wheat group: 125.9 (SEM 1.4); whole grain wheat + oats: 131.7 (SEM 1.4); control: 131.2 (SEM 1.4); P = 0.019 Diastolic blood pressure (mmHg): whole grain wheat group: 75.7 (SEM 0.8); whole grain wheat + oats: 78.4 (SEM 0.8); control: 79.1 (SEM 0.8); P = 0.26 Medications used: monitored but not reported |
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Interventions |
Whole grain diet group: 2 intervention groups: whole grain wheat and whole grain wheat and oats Control: refined grain foods Description of dietary intervention: after a 4‐week run‐in period on the refined grain diet, the intervention groups had 3 servings/d of refined cereal foods replaced by either 3 servings of whole wheat foods (70 to 80 g wholemeal bread and 30 to 40 g whole grain cereals) or with 1 serving of whole wheat foods and 2 servings of oats. The study foods, both refined and whole grain, were products widely available from UK food retailers. Apart from the whole grain foods supplied, participants selected their own foods to eat and advice on which foods to replace with whole grain servings was standardised to each participant's regular diet. Incentives: not reported Co‐interventions in both groups: none Assessment of dietary adherence: 7‐day food diaries, 3 times during the intervention. Was the diet energy reduced? no Comparability of diet composition: no differences in macronutrients, except for fibre (as expected). (See Table 2.) Change in diet over time: reported at baseline and week 12. (See Table 2.) |
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Outcomes | Total cholesterol, triglycerides (TAG), HDL cholesterol, LDL cholesterol, Apo A‐I, Apo B, BMI waist circumference, systolic BP, diastolic BP, pulse pressure, heart rate, stiffness index, insulin, glucose, HOMA‐IR, revised QUICKI, h CRP, IL‐6 | |
Funding/conflicts of interest | UK Food Standards Agency (grant NO2035), Scottish government (Rural and Environment Research and Analysis Directorate). Oat cakes were supplied by Paterson Arran Ltd. | |
Notes | ||
Risk of bias | ||
Bias | Authors' judgement | Support for judgement |
Random sequence generation (selection bias) | Low risk | Web‐based randomisation system, random permuted blocks stratified by age, gender, and BMI |
Allocation concealment (selection bias) | Low risk | Off‐site allocation |
Blinding of outcome assessment (detection bias) All outcomes | Low risk | Outcome assessors blind. |
Incomplete outcome data (attrition bias) All outcomes | High risk | Loss to follow‐up higher in control group: 63/76 completers, 11 voluntarily withdrew, 2 excluded; whole grain wheat group 73/77 completers, 4 voluntarily withdrew; whole grain wheat + oats group 70/73 completers, 2 voluntarily withdrew, 1 excluded. Reasons for higher withdrawal in control group not clear. |
Intention to treat analysis | Unclear risk | Not reported |
Selective reporting (reporting bias) | Unclear risk | Blood pressure outcomes provided by author as not reported in publications except graphically. Unclear if all variables reported at baseline are outcomes. |
Groups comparable at baseline | Unclear risk | Yes, except for both systolic and diastolic blood pressure, which were lower in the whole grain wheat group than in the whole grain wheat + oats group and the control group |
Other bias | Low risk | Sample size was based on total cholesterol and LDL cholesterol. Power calculations indicated 60 participants per group would give sufficient power to detect effects of 5% to 7%. This was met. |