MENU 2016.
| Methods | Metabolism, Exercise and Nutrition at UCSD (MENU) RCT, parallel, (walnut rich moderate fat diet vs moderate fat diet), 12 months Summary risk of bias: moderate or high |
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| Participants | Overweight and obese women, of whom half were insulin resistant N: 82 intervention, 81 control (analysed, intervention: 65 control: 61) Level of risk for CVD: low Men: 0% intervention, 0% control Mean age (SD) years: 51 (NR) intervention, 50 (NR) control Age range: 22‐67 years intervention, 25‐72 years control Smokers: not reported Hypertension: not reported Medications taken by at least 50% of those in the control group: not reported Medications taken by 20%‐49% of those in the control group: not reported Medications taken by some, but less than 20% of the control group: 10% were on cholesterol medications Location: USA Ethnicity: Hispanic 18% intervention, 14% control; black 9% intervention, 3% control; Asian American 1% intervention, 4% control; white non‐Hispanic 71% intervention, 78% control. |
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| Interventions | Type: food and advice Comparison: walnut rich moderate fat diet (ALA) vs moderate fat diet (MUFA) Intervention: advice to follow walnut‐rich higher fat diet (35%E fat with limited SFA, MUFA encouraged, including 42 g/d walnuts (provided by study), 45%E CHO, 20%E protein). Participants given print materials on diet and exercise, attended group sessions weekly for 1st 4 months, biweekly for next 2 months, then monthly to 1 year), provided web‐based tracking for dietary constituents, scale, pedometer, measuring cups and exercise videos. Regular dietetic and group leader support. Clinic visits were at 0, 6 and 12 months. Dose: ˜4.2 g/d ALA (calculated based on 42 g/d intake of walnuts) Control: exactly as intervention for goals, materials and support except higher fat diet did not include walnuts (35% E fat with limited SFA, MUFA encouraged, 45%E CHO, 20%E protein) Compliance: walnut consumption reported on form and nuts provided. Red blood cell ALA significantly higher in intervention at 12 months than control Duration of intervention: 12 months |
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| Outcomes | Main study outcome: body weight Dropouts: 13 of 82 intervention, 12 of 81 control Available outcomes: weight, waist circumference, HDL and LDL cholesterol, triglycerides, insulin, glucose, HOMA‐IR, HOMA‐beta, CRP and IL‐6 (estradiol, SHBG, nutrient gene interactions, physical activity and heart rate also presented) Response to contact: no reply received to date |
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| Notes | Study funding: National Cancer Institute and California Walnut Commission | |
| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Low risk | Randomisation stratified by age and insulin resistance |
| Allocation concealment (selection bias) | Unclear risk | No details |
| Blinding of participants and personnel (performance bias) All outcomes | High risk | Open study, participants were advised on their diets extensively |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | Blinding not mentioned, so unclear for their primary outcome, weight |
| Incomplete outcome data (attrition bias) All outcomes | Low risk | Paper states ITT analysis but 25 dropouts (15%) not included in 1 year data, but dropout reasons clear |
| Selective reporting (reporting bias) | Low risk | Pre‐registered, all mentioned outcomes reported at 12 months |
| Attention | Low risk | Appear very equal |
| Compliance | Low risk | Statistically significant difference between intervention and control arms for ALA in blood cell membranes at 12 months |
| Other bias | Low risk | None noted |