Food Technology magazine's contributing editor Linda Milo Ohr has written about some food that have a beneficial effect on lowering blood pressure.
Results from a study of 32 pre-hypertensive adult subjects showed that a patented grape seed extract may help to lower both systolic and diastolic blood pressure after just eight weeks (Polyphenolics, 2013a).
A study (Katz et al, 2012) showed that 56 g of walnuts a day cut systolic blood pressure and did not lead to weight gain.
Another study (West et all 2012), 28 subjects with high cholesterol showed reductions in systolic blood pressure after one serving of pistachios a day.
During a 12-week study, researches gave 46 pre-hypertensive subjects raisins or other snacks equal in calorie value three times a day. At weeks four, eight and 12 weeks, subjects eating the raisins showed a significantly reduced systolic blood pressure (Bays et al, 2012).