A recent Australian review examined nutrition and preventing stroke. It found: antioxidant vitamins C and E, B vitamins, and calcium do not prevent stroke. (Exception – treating folic acid and D deficiences may be preventative). The Mediterranean Diet, due to its fish and fruit content, reduces stroke. Likewise, the Dash Diet, with lower salt intake, is effective. For you chocoholics, >70% cocoa in moderation may be preventative.  http://www.thelancet.com/journals/laneur/article/PIIS1474-4422(11)70265-4/fulltext