High cholesterol is usually anything over 200 mg/dL (milligrams per deciliter) and can lead to all kinds of health problems such as an increased risk of stroke and heart disease. The top causes of high cholesterol are pretty well known but a lot of people ignore this information. That's easy to do however because time goes by very quickly as we age. At 20, 30 takes forever to get here but at 30, 40 seems to approach very, very quickly.