This thesis investigated the hypothesis that modifying the overall dietary pattern to conform with UK dietary guidelines would lead to significant reductions in cardiovascular risk factors when compared to a conventional UK diet. Two additional studies were undertaken: a qualitative study exploring factors influencing compliance to the dietary intervention and an investigation into whether a cardioprotective dietary pattern is more expensive than a conventional UK dietary pattern. An integrated dietary intervention consistent with UK dietary guidelines (5 portions of fruit and vegetables per day, increased consumption of whole grain cereals and oily fish; moderate total fat; reduced saturated fat, added sugars and salt intake) was developed. Changes in daytime systolic blood pressure, ratio of total cholesterol to HDL cholesterol, and endothelial function were compared after 12 weeks in healthy adults aged 40 to 70 years following either the cardioprotective diet (n=80) or a representative UK diet (n=82). There was a significant reduction in daytime SBP of 4.2 mmHg and a 4.2% reduction in TC:HDL-C compared to the control diet, however endothelial function did not differ between groups. Participants randomised to the cardioprotective diet (n=8) were interviewed in a qualitative study. Motivators identified were sociocultural; many specific to the study context. Elements were identified that could be implemented outside of a scientific study environment. Participants adopted a number of strategies in response to social and environmental barriers, some of which would be hard to maintain in the longer term. A retrospective analysis of food records completed by a subset of participants (n=40) found there was no difference in the cost of the two diets at endpoint, nor was there a difference in dietary costs compared to baseline. The work described suggests that the adoption of a dietary pattern consistent with UK dietary guidelines does improve cardiovascular risk. Cost may not be a barrier to adopting a cardioprotective dietary pattern in individuals who are not specifically of lower socioeconomic status. These findings and factors affecting compliance to the intervention are discussed in relation to the translation beyond the trial setting to inform public health initiatives for cardiovascular disease prevention.