​​​Cholesterol is a waxy, fat-like substance found in all cells of the body. It is in the foods you eat, and your body makes it. Some cholesterol is good for you. You need it in order for your body to make hormones, vitamin D and substances that help you digest foods. However, when there is too much cholesterol in your blood, it can lead to serious problems.

There are two kinds of cholesterol at work in your body, and it’s important to maintain healthy levels of each:

• High-density lipoprotein (HDL)—or “good” cholesterol—carries cholesterol from other parts of your body to your liver, which works to remove cholesterol from your body.
  
• Low-density lipoprotein (LDL)—or “bad” cholesterol—is associated with heart disease. The more LDL in your blood, the greater chance you have of developing heart disease.
  

Blood tests can easily measure cholesterol levels. A blood test for cholesterol should include the entire lipoprotein profile: LDL, total cholesterol, HDL, and triglycerides. It is also possible to measure LDL levels by themselves, but LDL levels can be reliably calculated using total cholesterol and HDL levels. Cholesterol is measured in milligrams (mg) per deciliter (dL) of blood. Your total cholesterol number should be less than 200 mg/dL. Anything between 200 and 239 mg/dL is considered borderline high, and anything over 240 mg/dL is considered high.

 To obtain an accurate cholesterol reading, doctors advise:

• Do not eat or drink anything but water for 12 hours before the test. (Some recent studies indicate that fasting is not really necessary for routine screening. Check with your doctor.)
  
• If the test results are abnormal, a second test should be performed between 1 week and 2 months after the first test.
  

Cholesterol can slowly build up in the blood vessels that deliver oxygen-rich blood throughout the body. That buildup is called plaque. Plaque can cause atherosclerosis (hardening or narrowing of blood vessels over time).

Coronary heart disease (CAD) occurs​ when the arteries that lead into the heart are affected or blocked. Large amounts of plaque buildup may prevent blood from returning to the heart and may cause a heart attack.

How to lower your cholesterol

Lowering your cholesterol may slow down, reduce or even stop plaque from building up. Improving your diet and getting enough exercise will help lower your cholesterol. Foods high in saturated fat or that contain trans fats raise your cholesterol levels. Check the food nutrition label if you are unsure of how much fat is in a certain food.

The main lifestyle principles to reduce unhealthy cholesterol levels include:

• Consume a heart-healthy diet (with emphasis on vegetables, fruits, and whole grains)
• Make vegetables, fruits, and whole grains the focus of your diet
• Include low-fat dairy products, poultry, fish, legumes (beans), nontropical vegetable oils, and nuts
• Limit intake of sweets, sugar-sweetened beverages, and red meats
• Engage in regular physical activity (40 minutes of moderate to vigorous exercise 3 to 4 times a week)
  
• Maintain a healthy body weight (under a doctor’s supervision when necessary)
  
• Don’t smoke
  
• Control high blood pressure and diabetes (for patients who also have these conditions)
  

 Your doctor may also prescribe medications that help control cholesterol levels.