A study was undertaken with 1710 men in Chicago, which measured their changes in blood pressure over a 7 year time period based on different diets.
The average change in blood pressure for the group was an increase of 1.9/0.3 mmHg per year (systolic / diastolic). The rise in SBP over a 7 year period was 2.8mmHg and 2.2 mmHg less for men who consumed >14 cups of vegetables and fruits per month respectively. On the other hand, beef/veal/lamb/poultry intakes are all related with an increase in SBP / DBP levels. The report concludes that the results support the concept that diets higher in fruits & vegetables and lower in meats may reduce the risk of developing high BP.
Relation of Vegetable, Fruit, and Meat Intake to 7-Year Blood Pressure Change in Middle-aged Men. The Chicago Western Electric Study