NDHS Open 1st mod 1968.

Methods	RCT
Participants	Free living men (USA) CVD risk: low Control: randomised 382, analysed 341 Intervention C: randomised 390, analysed 348 Mean years in trial: control 1.0, C 0.9 % male: 100 Age: unclear (all 45‐54)
Interventions	Modified fat diet vs. usual diet Control aims: total fat 40%E, SFA 16‐18%E, dietary chol 650‐750mg/d, P/S 0.4 Intervention C: total fat 40%E, SFA <9%E, dietary chol 350‐450mg/d, PUFA 18‐20%E, P/S 2.0 Control methods: dietary advice to reduce saturated fat and cholesterol (plus 10 follow up visits with nutritionist), purchase of 'usual fat' items from a trial shop Intervention C methods: dietary advice to reduce saturated fat and cholesterol (plus 10 follow up visits with nutritionist), plus purchase of appropriately reduced and modified fat items from a trial shop Total fat intake (through study): C 34.4 (sd unclear)%E, cont 34.9 (sd unclear)%E Saturated fat intake (through study): C 7.4 (sd unclear)%E, cont 11.6 (sd unclear)%E Style: food provided Setting: community
Outcomes	Stated trial outcomes: lipid levels and dietary assessment Data available on total mortality? no Cardiovascular mortality? yes (no events) Events available for combined cardiovascular events: fatal and non‐fatal MI, peripheral vascular events Secondary outcomes: cancer diagnoses, total and non‐fatal MI Tertiary outcomes: none (total cholesterol and BP data presented but no variance info)
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Stratified randomisation by the statistical centre
Allocation concealment (selection bias)	Low risk
Blinding (performance bias and detection bias) All outcomes	Low risk	All reduced saturated fat and purchased blinded foods from a trial shop, double blind.
Incomplete outcome data (attrition bias) All outcomes	High risk	Dropouts do not appear to have been followed for death or CV events. Deaths, cancer and CV events for participants otherwise still included in the study were collated as a reason for study exclusion
Selective reporting (reporting bias)	Low risk	Not relevant for primary and secondary outcomes as all trialists asked for data
Other bias	Low risk
Free of systematic difference in care?	Low risk	Trial shop used by both groups, plus dietary advice. See Control and Intervention Methods in Interventions section of the Table of Characteristics of Included Studies
Free of dietary differences other than fat?	Low risk	See Control and Intervention Aims in Interventions section of the Table of Characteristics of Included Studies