High cholesterol is a pretty common issue in the U.S. In fact, according to the Centers for Disease Control and Prevention (CDC)Trusted Source, nearly 94 million U.S. adults ages 20 or older have what could be considered borderline high cholesterol.

However, because this condition can often present without any real symptoms, you may not even know you have it until you visit your doctor.

If you’re wondering what causes high cholesterol, what to do if you’ve been diagnosed with it, and if there are ways to reverse it (hint: there are), read on for all the answers.

What is cholesterol? Cholesterol is a type of lipid. It’s a waxy, fat-like substance that your liver produces naturally. It’s vital for the formation of cell membranes, certain hormones, and vitamin D.

Cholesterol doesn’t dissolve in water, so it can’t travel through your blood on its own. To help transport cholesterol, your liver produces lipoproteins.

Lipoproteins are particles made from fat and protein. They carry cholesterol and triglycerides, another type of lipid, through your bloodstream. The two major forms of lipoprotein are low-density lipoprotein (LDL) and high-density lipoprotein (HDL).

LDL cholesterol is any cholesterol carried by low-density lipoproteins. If your blood contains too much LDL cholesterol, you may be diagnosed with high cholesterol. Without treatment, high cholesterol may lead to many health issues, including heart attack and stroke.

High cholesterol rarely causes symptoms in the beginning. That’s why it’s important to get your cholesterol levels checked on a regular basis.