Cholesterol is a fat-like substance found in the bloodstream and in the membranes of every cell of your body. Your body uses cholesterol to make certain hormones, bile acids (used in digestion), vitamin D and other important substances — so you need a certain amount of cholesterol for your body to function properly. However, your body makes all the cholesterol it needs, so any cholesterol you get from food is unnecessary and potentially harmful to your health, especially to your heart.
Where does cholesterol come from?
Cholesterol comes from two sources: your body and the food that you eat. Cholesterol from food comes from animal products — meat, fish, eggs, butter, milk, cheese, etc. Food from plants doesn't have any cholesterol. However, now there is another source of cholesterol called trans fat. Trans fat is used in a lot of processed foods (you'll know it's there when you see the words "hydrogenated" or "partially hydrogenated" on the label). Trans fat is not itself a form of cholesterol; instead, it causes your body to make more cholesterol on its own, more than it actually needs.
Why so many numbers?
Your cholesterol is not as simple or straightforward to remember as your blood pressure or BMI. That's because there are different kinds of cholesterol, plus another substance called triglycerides to take into consideration when assessing your cholesterol level. To understand more fully, you have to know how cholesterol exists in the body.
Cholesterol circulates in the bloodstream, but because it's a fat, it can't travel by itself. Think of oil and water. In this situation, cholesterol is the oil and your blood is the water. They don't mix. That's why cholesterol has to travel with something else — protein. This cholesterol-protein combination is called a lipoprotein. There are two main types of lipoproteins, low-density lipoprotein (LDL) and high-density lipoprotein (HDL). Added together, these two lipoproteins make up your total cholesterol. Like LDL and HDL, triglycerides are a type of fat, or lipid, found in your blood. People with high triglycerides often have a high total cholesterol. When doctors check your blood for cholesterol — a test called a lipid profile or lipid panel — they will also check your triglyceride level.
How often should I have my cholesterol checked?
If you are twenty years old or older, you should have your blood cholesterol checked by a healthcare professional once every five years. If you are a man over 45 or a woman over 55, you should have your cholesterol checked more frequently. Also, if your cholesterol is high or borderline high, regardless of your age, your doctor will probably want to monitor it more often.
How do they check cholesterol?
To assess your cholesterol, you will have to have a fasting lipoprotein profile. Your doctor will ask you not to eat or drink anything (except water) for 9 to 12 hours, then he or she will take a blood sample that will be sent to a lab to determine your total cholesterol, LDL, HDL and triglycerides. If you eat or drink anything other than water before your blood test, only your readings for total cholesterol and HDL will be useable. Cholesterol is measured in milligrams per deciliter of blood (mg/dL).
What is a healthy cholesterol level?
Healthy cholesterol levels are different for different people, depending on your underlying risk for heart disease. For most everyone, a healthy total cholesterol level is below 200 mg/dL. HDL for women should be above 50 mg/dL and for men above 40 mg/dL. And while the ideal level for LDL is below 100 mg/dL, most people are okay with an LDL below 130 mg/dL. LDL is the most important of these numbers for determining your risk for heart disease, heart attack and stroke. A healthy triglyceride level is below 150 mg/dL.
Some physicians, rather than use absolute numbers, prefer to measure cholesterol in the form of a ratio of total cholesterol to HDL. The ratio is therefore obtained by dividing your total cholesterol number by your level of HDL. The optimum cholesterol ratio is 3.5:1. A ratio of 5:1 is considered high.
If you are at a high risk for heart disease, these guidelines for healthy cholesterol may not be accurate for you. You should talk to your doctor about your underlying risks to determine the right cholesterol goals for you. Things that may put you at high risk include a previous heart attack, diabetes, smoking, high blood pressure, low HDL, a family history of early heart disease, or being older than 45 if you're a man or older than 55 if you're a woman.