Curcumin is the coloring principle of turmeric, or curcuma root, extracted as an orange yellow crystalline substance, C14H14O4, with a green fluorescence. More commonly, it is known as a spice of the ginger family.
There is no direct evidence but the indirect evidence seems to be building up that curcumin (component of most curry formations) can lower blood pressure and improve cardiac health. Particularly interesting is that it seems to works on diabetic conditions which known to go hand-in-hand with many high blood pressure conditions.
In my personal use, it seems to work. I notice after a few days of steady use, a slight improvement in BP readings. I happen to like the flavor, try it, if you don’t then obviously it not for you, but if you do like it, another opportunity to improve is opened.
There are high powered supplements available, but it seems that these may contribute to the formation of oxalate and kidney stones, so like many dietary benefits, moderation and periodic use instead of continual overdosing is the wiser route.
http://www3.interscience.wiley.com/journal/118729017/abstract?CRETRY=1&SRETRY=0