When we talk about dietary cholesterol, we mean cholesterol that's contained in the food we eat. The only foods that contain cholesterol are animal foods-like meat, poultry, fish, eggs, milk, and cheese. Many people believe foods like avocados, peanuts, and beer contain cholesterol, but they don't.
Serum cholesterol is the cholesterol that's in our blood.
For a healthy heart, it is best to keep serum cholesterol not higher than 200. When it gets higher than this, it can build up in the arteries, causing them to narrow. This forces the heart to work harder in order to pump blood. In time, it can cause heart disease. Scientists noticed that people with heart disease had high levels of serum cholesterol.