Onions, and garlic do lower blood pressure. It is the quercitin in oinions that has the anti hypertensive action. Quercitin can be taken in supplement form as well. The trial of onions, and findings can be read here: http://www.ncbi.nlm.nih.gov/pubmed/22332099
A recent trial confirms that olive leaf lowers blood pressure as well as the pharmaceutical drug, Catapril. The doseage amounts where 500mg twice a day. I would not combine oilve leaf with your blood pressure meds, it may lower it too much. Which is just as bad as it being too high.
The Trial can be read here http://www.ncbi.nlm.nih.gov/pubmed/21036583
Another "heart healthy" componet would be reservatol, an element found in red wine, chocolate. (yeah!!!) The french are known to drink red wine, and have less incidence of heart disease, Known as the 'french parody". It also can be taken in supplement form. The study: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC382004...
My article about heart health gives other useful information, as well as where to order. A liquid may be used as well. By placing a few drops under the tongue, it bypasses all other organs, and is straight into the blood stream. https://hubpages.com/health/Heart-Health-Natural-S... Hope it helps.