People with underlying heart disease probably should avoid consuming more than 300 milligrams of caffeine per day. People have no way of following the advice since manufacturers are not required to list the amount of caffeine in their products. Women are affected by caffeine far more than men. Age, overall, health, weight and a host of other lifestyle factors also enter the picture. How can you determine your own personal risk level? You can start by figuring out how much caffeine you present, consume and how it is affecting your life.