The objective was to investigate the effects of substitution (SUB) dietary guidelines (DG) targeted at prevention of ischemic heart disease (IHD) on dietary intake and IHD risk factors in Danish adults with minimum one self-assessed IHD risk factor. A 6-month single-blinded parallel randomised controlled trial with a follow-up at month 12 included 219 subjects (median age 51 years, 59% female, 73 % overweight or obese) randomised into a SUB DG, an official (OFF) DG or a control group following their habitual diet (HAB). Participants in the DG intervention groups received bi-weekly reminders of their DG and recipes for dishes and the HAB group received a greeting. Dietary intake and fasting blood, anthropometric, and blood pressure measurements were obtained at baseline, month 6 and month 12. Linear regression analyses were applied. At month 6, when compared with the HAB, the SUB had a greater impact on the extent of dietary changes with increased intake of whole grains, dietary fibre, and low fibre vegetables compared with the OFF DG and both DG groups had similar decreased percentage of energy (E%) intake from saturated fatty acids. The extent of dietary changes were similar at month 12. No overall significant changes from baseline were found in blood pressure (BP), anthropometrics and IHD risk markers. In conclusion, both SUB and OFF DG resulted in cardioprotective dietary changes. However, neither the SUB nor the OFF DG resulted in any overall effects on the selected intermediate risk factors for IHD.