Medical form with words cholesterol HDL LDL

Cholesterol 101

Patients are understandably confused about cholesterol, but here is what you need to know.

Cholesterol produces some hormones and builds vital structures in your body. But too much—referred to as high cholesterol—can build up in your arteries and lead to heart attack, stroke, and other cardiovascular diseases. 

That's why it’s important to get tested and know your cholesterol numbers; they show how much cholesterol is circulating in your blood.  

We asked Sonia Tolani, MD, an expert in cardiovascular disease and cholesterol management, to explain the good and the bad about cholesterol, and how to have healthy levels. To start, she says, “Know your cholesterol numbers and keep them in check. You are in control. Maintaining normal cholesterol levels significantly reduces your risk of heart attack and stroke.” 

What is cholesterol? 

Cholesterol is a substance that circulates in your blood. Your liver produces most of the cholesterol in your body. Other cholesterol enters your body through food.  

The two most important types of cholesterol:  

  1. LDL (low-density lipoprotein)  
    • This is the bad one; your target number depends on your risk for heart disease. Most people should aim for an LDL below 100, but those with diabetes or who have cardiovascular disease should aim for lower, below 70.  
  2. HDL (high-density lipoprotein) 
    • This is the good one. For women, a good level is above 60; for men, it's above 40. 

Too much LDL, or too little HDL, increases health risk.  

Where does cholesterol come from? 

Your liver and cells in your body produce about 80% of the cholesterol in your blood. Food brings in the other 20%. Food that’s high in trans and saturated fats contributes to bad levels of cholesterol (not food that's high in cholesterol, as once was thought). Bad means bad for your health. 

When you take in more cholesterol, your liver reduces its cholesterol production and removes the excess. But some people’s livers don’t do this well, because of their genes.   

Trans and saturated fats 

Trans fats are primarily artificial (created by adding hydrogen to vegetable oil to make it more solid) but some occur naturally in animal products. The Food and Drug Administration banned trans fats in the United States in 2018, with the final allowable manufacturing date of Jan. 1, 2021. But some packaged food may still have trans fat because of how it is processed. 

Processed and packaged food includes: 

  • Biscuits 
  • Cookies 
  • Crackers 
  • Frosting 
  • Microwave popcorn 
  • Pie crusts 
  • Pizza 
  • Vegetable shortening and oil 

Look at the nutrition facts panel on packaged food to see how many trans fats it contains.   

In addition to increasing heart disease and stroke risk, consuming trans fats increases risk of type 2 diabetes. The American Heart Association recommends that most people reduce or eliminate consumption of trans fats. 

Saturated fats occur naturally in many foods, such as animal-based and tropical oils, including: 

  • Beef 
  • Butter, cheese, cream
  • Coconut 
  • Lamb 
  • Lard  
  • Pork 
  • Poultry, especially with skin 
  • Palm oil 

Research shows that not all saturated fats are bad to eat. The American Heart Association recommends that most people limit daily consumption of saturated fats to 13 grams per day. 

Know your numbers 

How much cholesterol do you have?  

The amount of cholesterol you have depends on genetics, diet, age, activity, assigned sex at birth, and other factors. 

Where, when, and how do I get a cholesterol test? 

According to the Centers for Disease Control and Prevention: 

  • Healthy adults should have their cholesterol checked every four to six years. 
  • Children should have their cholesterol checked at least once between ages 9 and 11 and again between ages 17 and 21. 
  • People with family history of heart disease should get their cholesterol checked more often. 

Ask your doctor about the lipid panel blood test.  

Keep cholesterol levels in check (low!) 

  • Eat a low saturated fat diet, like the Mediterranean-style diet.  
  • Exercise regularly (30 minutes of moderate exercise five days a week of moderate exercise or 75 minutes of vigorous exercise a week).  
  • Maintain a healthy weight.  

In addition, due to genetic factors, some people need medications to keep their cholesterol in check. Talk to your doctor about your known risk factors. 

High cholesterol is one of the major risk factors for cardiovascular diseases that you can control with healthy eating and/or medication. The first step is knowing your cholesterol numbers. 


Sonia Tolani, MD, is assistant professor of medicine at Columbia University's Vagelos College of Physicians and Surgeons and co-director of the Columbia Women's Heart Center. She is an expert in consultative cardiology, preventive medicine, and women's heart disease, including the treatment of gestational hypertension and preeclampsia.