What's The Causes For Mini Strokes?

I am going to assume and hope that you are talking about m-i-n-i strokes and not m-i-m-i strokes.  Anyway, my mom has had these and they seem to come in spurts on and off over the years.  She has an off the wall cholesterol level so that could definitely be one cause.  Any stroke caused by a stopping of blood to the brain, just like a heart attack is a stoppage to the heart.  Smoking can also be a factor since smoking causes plaques to build up inside the veins and they in turn become blocked so don't allow blood flow(think of a straw with a rock caught inside it).  Diet and medication should be given to help blood flow so a stoppage does not become permanent or cause a buildup of pressure behind the block and stretching of the vein or artery at the pressure site then a blowout(aneyurism).
See your doctor right away, and don't fluff off the diet advice, it could just save your life.