The three most important risk factors for heart disease are high blood cholesterol levels, high blood pressure, and smoking. The major factors that influence one's blood cholesterol level are the intake of saturated fat and cholesterol, and being overweight. Saturated fat in the diet is more effective in elevating blood cholesterol levels than is dietary cholesterol itself. Furthermore, saturated fat will raise blood cholesterol levels twice as much as dietary polyunsaturated fat will lower those levels. Saturated fat and cholesterol generally occur together in most animal products.
Fish is an exception.
While it is rich in polyunsaturated fat, fish does contain cholesterol. Blood cholesterol levels can be lowered by a number of dietary factors. Following a vegetarian diet normally results in a significantly lower blood cholesterol level, since the vegetarian diet contains many of the protective factors. Not all brans were created equal. Rice bran and oat bran are both effective for lowering cholesterol levels while wheat bran has no effect.