Lots of evidence is being collected to show that eating raisins might help lower blood pressure. Routine consumption according to one group of scientists at the Louisville Metabolic and Atherosclerosis Research Centre, University of Kentucky, USA has shown that three portions a day of raisins lowers blood pressure much more effectively compared to an equivalent energy (equicaloric) snack (Bays et al., 2012). The findings come from the CAMELOT study which investigates a number of cardiovascular benefits.

Raisins have a high fibre and potassium content plus other phytonutrients of benefit to humans. The 12 week randomised and controlled study compared the blood pressure in 46 men and women with borderline blood pressure issues (hypertension).  They consumed a portion of raisins three times a day compared to an energy equivalent of other snacks. They studied both systolic (SBP) and diastolic blood pressure (DBP) and found a reduction at the time points of measurement of 4,8 and 12 weeks, in the SBP. The snacks did not have any effect on blood pressure at the equivalent time points.

It would be useful to know what the serving size was for each portion  and what the actual snacks were.

Reference

Bays, H.E., Schmitz, K., Christian, A., Ritchey, M., Anderson, J., (2012) Raisins and Blood Pressure: A Randomized, Controlled Trial.  J. Am Coll Cardiol. 59(13s1) E1721-E1721. doi:10.1016/S0735-1097(12)61722-7