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. 2017 Aug 24;2017(8):CD005051. doi: 10.1002/14651858.CD005051.pub3

Harris 2014.

Study characteristics
Methods Setting: USA
Design: randomised parallel study
Dates: March 2009 to May 2011
Intervention duration: 12 weeks (6 weeks weight maintenance diet, followed by 6 weeks weight loss diet)
Follow‐up: no postintervention follow‐up
Focus: to compare the effects of whole grain diets compared to refined grains in people with or at risk of metabolic syndrome (overweight and obese individuals with increased waist circumference and 1 or more other MetS criteria).
Participants N: 60 randomised (25/28 completers in the whole grain intervention group and 25/32 in the control group).
Inclusion criteria: male and female, aged 35 to 55 years (overweight and obese individuals with BMI 25 to 42 kg/m2; with increased waist circumference >/= 102 cm in men and >/= 88 cm in women; and 1 or more other MetS criteria: fasting plasma glucose >/= 100 mg/dL, fasting serum triglycerides >/= 150 mg/dL, BP >/= 130/85 mmHg and/or fasting serum HDL cholesterol < 50 mg/dL in women or < 40 mg/dL in men).
Exclusion criteria: use of medications affecting glucose or lipid metabolism, frequent (> 4 times/wk) use of anti‐inflammatory medications, pregnancy or lactation, smoking, high alcohol intake (> 14 drinks/wk), and diagnosed CVD, diabetes, or inflammatory disease.
Age (years): 35 to 55 years: whole grain: 46.4 (SD 5.9); control: 45.8 (SD 6.0)
Sex (% men): whole grain: 48%; control: 52%
Ethnicity: US (ethnic composition not reported)
Baseline cardiovascular risk status:
BMI (kg/m2): whole grain intervention: 32.9 (3.5); control: 33.5 (4.0)
Total cholesterol (mmol/L): not reported
HDL cholesterol (mmol/L): whole grain intervention: 6 (0.28); control: 1.06 (0.39)
LDL cholesterol (mmol/L): not reported
Systolic blood pressure (mmHg): whole grain intervention: 123 (12); control: 125 (12)
Diastolic blood pressure (mmHg): whole grain intervention: 83 (10); control: 85(6)
Medications used: whole grain group: 48%; control: 40%. Blood pressure medications were allowed.
Interventions Whole grain diet group (whole grain products, variety of grain types)
Control (refined grain products)
Description of dietary intervention: the whole grain diet group consumed all WG products from a variety of grain types; those receiving the control diet consumed the refined grain counterpart. The top 3 grains consumed were wheat, oats, and rice with the whole grain diet and wheat, rice, and corn with the refined grain diet. Wheat products constituted 77% of the whole grain diets and 63% of the control diets. Diets were tailored to individual energy requirements; the whole grain diets contained between 163 and 301 g/whole grain per day, and the refined grain diets no whole grains. Both diets comprised an isocaloric weight maintenance diet for 6 weeks followed by an energy‐reduced diet for the next 6 weeks (reduced by ~500 kilocalories/d). All meals and snacks were prepared at metabolic kitchens on the university campus. Participants had to go to the kitchen to pick up or eat their meals.
Incentives: not reported
Co‐interventions in both groups: none
Assessment of dietary adherence: compliance forms (all food provided)
Was the diet energy reduced? yes
Comparability of diet composition: both diets were designed to have the same macronutrient composition and to meet National Cholesterol Education Program guidelines for saturated fat (< 7% E), mono‐ and polyunsaturated fats (~10% and ~7% E), total cholesterol (< 200 mg/d), and total fibre (> 20 g/d). Participants consumed all study foods and did not consume any additional non‐study foods on 86% of reported days. Physical activity levels were stable. (See Table 2.)
Change in diet over time: not reported
Outcomes Primary: weight, BMI, waist circumference, triglycerides, HDL cholesterol, glucose, systolic BP, diastolic BP. Secondary: total adiponectin, HMW adiponectin, leptin, TC:HDL ratio, LDL cholesterol, CRP, IL‐6, TNF‐alpha, insulin, HOMA‐IR, RMR, % adipose tissue.
Funding/conflicts of interest Bell Institute of Health and Nutrition (General Mills, Inc.) and National Institutes of Health grant M01RR10732. The first author was supported by a Nestle fellowship, alkylresorcinol analysis was funded by Cereal Partners Worldwide (a joint venture between General Mills, Inc. and Nestle SA).
Notes To enhance compliance, participants were given the option of taking a 1‐ to 2‐week break after the first 6‐week diet period.
Risk of bias
Bias Authors' judgement Support for judgement
Random sequence generation (selection bias) Low risk "randomly assigned ... using a computer‐generated random number assignment"
Allocation concealment (selection bias) Unclear risk "An unblinded study coordinator stratified participants by age, sex and BMI"
Blinding of outcome assessment (detection bias)
All outcomes Low risk "Outcome assessors (i.e. nurses and technicians) were blinded"
Incomplete outcome data (attrition bias)
All outcomes High risk Reasons for attrition reported: 7 lost to follow‐up in control group (none due to diet issues), 3 lost to follow‐up in whole grain group (2 due to diet issues), similar rates of loss to follow‐up, but differential rates in those withdrawing because of the diet.
Intention to treat analysis Unclear risk "Per protocol analysis included only the data from participants who completed both phases of the study"
Selective reporting (reporting bias) Unclear risk Reports all relevant outcomes but not enough information to judge.
Groups comparable at baseline Low risk Yes, except for triglycerides, which were higher in the control group. Unclear risk for triglycerides
Other bias Unclear risk Power calculations used body composition (% of abdominal AT) as outcome variable (not a primary outcome of this review), which required a sample size of 50. This was met, but power relevant to measuring changes in lipids or blood pressure not reported.