So what are your cholesterol numbers?

If you're drawing a blank right now, it could mean you're overdue for the routine blood test that helps give a heads-up on your risk for heart problems or a stroke.

Cholesterol is a fatty substance that helps our bodies function properly. The liver makes the cholesterol we need, but we can get more from what we eat.

The two main types of cholesterol are:

• Low-density lipoprotein (LDL), or bad cholesterol. Excess amounts can build up in the walls of arteries, narrowing the passageways and reducing blood flow to the heart and brain. This is called atherosclerosis—or hardening of the arteries—and it increases your risk for heart disease, a heart attack or a stroke.

• High-density lipoprotein (HDL), or good cholesterol. It helps clear excess cholesterol from blood vessels.

Keeping cholesterol levels in a healthy range helps reduce your risk for cardiovascular disease. But you won't know if your numbers need improving unless you have them checked. A simple blood test called a lipoprotein profile reveals your total cholesterol count, as well as levels of LDL and HDL cholesterol and another type of fat called triglycerides. Most adults should be tested at least every five years, according to the National Heart, Lung, and Blood Institute.

Your doctor can explain what your numbers mean along with what your cholesterol goals should be. If you need to improve your numbers, talk to your doctor about what you can do.

Lifestyle changes such as these can help:

• Adopt a healthy diet low in saturated fats, trans fat and cholesterol and high in fiber, fruits and veggies.

• Get at least 60 minutes of moderate-intensity aerobic activity each week.

• Lose weight, if needed.

Some people also need medicines to help lower cholesterol. But even if you take medications, lifestyle changes are important.

Take the first step. Ask your doctor about having your cholesterol checked, and learn your numbers.