While most people know that high cholesterol isn't a good thing, fewer people understand what contributes to or causes it. 

It can also be helpful to know how to lower cholesterol when high cholesterol levels have been discovered. 

"The foremost approach to managing high cholesterol is adopting healthy lifestyle modifications," says Christopher Pullins, MD, a family medicine physician at Mayo Clinic in Arizona. Such modifications include eating a healthy diet, losing weight if needed and getting sufficient sleep.

What causes high cholesterol?

Some such practices work to lower high cholesterol because the foods one eats contribute significantly to high cholesterol levels in most people. "When you eat foods high in certain types of saturated fatty acids, your liver takes that as a message to synthesize more cholesterol," explains Jill Weisenberger, MS, RDN, a Virginia-based registered dietician and author of "Prediabetes: A Complete Guide."

The worst foods for high cholesterol include full-fat dairy products such as whole milk, butter and cheese. Red meat, processed meats, fried foods and baked goods like cookies, cakes and doughnuts can also cause high cholesterol. In general, "avoid foods high in fat, sugar, and salt," says Caroline Susie, RD, a registered dietician and national spokesperson for the Academy of Nutrition and Dietetics.

She adds that lack of exercise can also contribute to high cholesterol since exercise decreases "bad" cholesterol known as LDL cholesterol by increasing one's "good" cholesterol known as HDL cholesterol. Exercise can also help one lose weight or maintain a healthy weight which can also increase more of one's good type of cholesterol.

Beyond diet and exercise, "it's important to note that some people have a genetic predisposition to elevated cholesterol levels which puts them at increased risk of early cardiovascular problems," adds Pullins. 

Smoking and alcohol can also cause high cholesterol. So can stress because it raises levels of certain hormones that can cause one's body to make more cholesterol, per the National Heart, Lung, and Blood Institute. 

What are the dangers of high cholesterol? 

It's important to understand what causes high cholesterol because there are real dangers associated with having it. "Specific types of cholesterol (LDL cholesterol) can contribute to the development of plaque buildup within the walls of blood vessels," explains Pullins. Such plaque buildup "can obstruct blood flow and potentially lead to severe outcomes," he says. 

These negative outcomes can include heart disease, diabetes and circulation issues related to a condition known as peripheral arterial disease. Even more severely, high levels of LDL cholesterol can increase one's risk for heart attack and stroke, per the Centers for Disease Control and Prevention (CDC). 

What are the symptoms or warning signs of high cholesterol? 

With such dire outcomes on the line, many want to know about the symptoms or warning signs associated with high cholesterol. "Regrettably, elevated cholesterol levels often remain unnoticed for years," says Pullins. That's because there are usually no obvious warning signs of high cholesterol and many symptoms related to high cholesterol such as nausea, fatigue, high blood pressure and shortness of breath are often explained away by illness or other conditions. 

Because of this, the CDC recommends having one's cholesterol levels checked at least every five years, a quick testing process that involves a blood draw. "Regular monitoring of cholesterol levels is advisable," echoes Pullins. He agrees that such tests should occur at least every five years but adds that it may need to be done more often for some people as recommended by one's primary care doctor. "The frequency of checks varies based on age and risk factors," he says.

High cholesterol leads to heart disease:Here's what to know so you can avoid it