I know you're asking about yogurt and you got some great responses, but I thought I would share with you some other tips that help with blood pressure. (My apologies if this is off-topic to you and you already know this :) )
DASH Diet - from the National Institutes of Health. This isn't a 'diet' that is a fad or wacky but a lifestyle plan that can help lower overall blood pressure. You don't have to buy any special products, just modify what/how you eat. It will help with all aspects of meal planning and can be found here:
And...my favorite foods to help the heart and lower blood pressure are steel cut oats, oatmeal, sweet potatoes, bananas, spinach, broccoli, kiwi, cantaloupe, and bananas.
I had high blood pressure 140-150s/100-110s and through NOTHING but modifying my diet and adding exercise, I dropped it to 100-110s/60-70s. You totally can do this :)