The effect of dietary patterns on blood pressure: insights for clinical practice

Hypertension or high blood pressure has been identified as a major risk factor for developing cardiovascular disease, stroke and kidney disease. To lower blood pressure, lifestyle changes such as following a healthy diet, weight loss and exercise have been recommended. This thesis draws on dietary data from a weight loss trial in which blood pressure was a secondary outcome. Previous studies investigating the effect of diet on blood pressure have mainly focussed on single nutrients such as sodium and potassium. Whilst this has been informative, food is not consumed as single nutrients but as whole foods, in different combinations which make up dietary patterns. An understanding of the interdependence between nutrients, foods and dietary patterns would help in translating dietary advice in clinical practice especially in food-based recommendations for blood pressure reduction. The central hypothesis of this thesis is that dietary patterns, characterised in terms of nutrients and foods, significantly influence blood pressure in adults. To assess the current level of evidence on the effect of dietary patterns on blood pressure, a systematic review and meta-analysis of randomised controlled trials was conducted. A dietary pattern characterised by high consumption of fruit, vegetables, whole grains, legumes, seeds, nuts, fish and low-fat dairy and low consumption of meat, sweets and alcohol resulted in significant reductions in systolic (SBP) and diastolic (DBP) blood pressure by 4.26 mm Hg and 2.38 mm Hg, respectively. Whether this would still relate to a clinical sample of overweight adults is an important question for practice.