Cholesterol is a type of fat. After your body produces cholesterol, your liver packages it and it flows through your blood. It usually has a negative connotation, but it’s a normal and healthy substance in the right amount.
Cholesterol helps send important signals all over the body. It wraps around other molecules to carry them through the bloodstream from one place to another. It’s also an important component of cell membranes, hormones, and vitamin D. But when you have too much cholesterol, it can build up in your arteries and lead to serious health problems.
Romit Bhattacharya, MD, explains how our bodies produce cholesterol and how much we actually need. Dr. Bhattacharya is a Mass General Brigham cardiologist and the associate director of the Cardiac Lifestyle Program at Massachusetts General Hospital.
Your liver has many functions, such as filtering blood and getting rid of toxins. It also processes and stores nutrients every time you eat. During this process, the liver makes cholesterol.
“There’s a funny misnomer out there that only 20% of your body’s cholesterol comes from the food you eat,” says Dr. Bhattacharya. “While that may be true, that’s kind of like saying, ‘I never eat pizza because I don’t order pizza in.’ But if I go to the grocery store and buy pizza dough, tomato sauce, cheese, and pepperoni, and I'm making pizza at home—isn't that the same thing?”
Your diet gives your liver the necessary ingredients to make cholesterol. In reality, 100% of your cholesterol comes from building blocks in your diet, whether from cholesterol itself (20%) or sugars and fats (80%).
Cholesterol circulates in your blood with the help of proteins, creating a molecule called a lipoprotein. Your blood has 2 main types of these cholesterol molecules:
You may hear HDL cholesterol referred to as “good” cholesterol, and LDL as “bad” cholesterol. However, Dr. Bhattacharya emphasizes that LDL is not an inherently bad molecule.
“Most of us just have way more of it than we need,” he says. “When we as humans are exposed to something at an abnormal level, then it can hurt us.”
The amount of cholesterol that your liver makes depends on how many ingredients you give it. Even if you have more than you need, your liver keeps producing cholesterol if it can.
“The liver is an incredibly resilient organ,” notes Dr. Bhattacharya. “It does its job of processing and shipping no matter what comes at it. It doesn’t want things to accumulate.”
When your body produces cholesterol, the amount of HDL compared to LDL matters. A healthy diet and lifestyle decrease LDL cholesterol, in addition to decreasing your total cholesterol. As a result, the ratio of HDL to LDL improves.
When you eat sugar, your body releases a hormone called insulin. Insulin controls many processes in the body, but importantly, it signals to your liver to make more cholesterol.
“What ends up happening in an unhealthy diet is that you ingest a lot of fat, cholesterol, and sugar,” says Dr. Bhattacharya. “So not only are you ingesting the building blocks for cholesterol, but the sugar and high insulin levels (particularly if you have insulin resistance or diabetes) turns up the speed and the amount of cholesterol that you produce.”
“Adults don’t need very much cholesterol at all, and our liver will produce all of that if we have a sufficiently varied and healthy diet,” says Dr. Bhattacharya. “No cholesterol level in the blood has ever shown to be too low for humans. In fact, people with genetic mutations that cause them to have extremely low levels of blood cholesterol—even in the single digits—show no significant side effects.”
He notes that babies potentially need the most cholesterol as they grow and develop. Yet babies are completely healthy having half as much cholesterol as the average American adult.
When you have lots of cholesterol in your body, it builds up wherever it can. Over time, it accumulates in the artery walls, leading to heart attack or stroke. You can do a few key things to reduce your cholesterol and prevent disease, including:
“In some cases, the combination of medication and lifestyle changes can actually begin to regress the buildup of cholesterol and fats,” says Dr. Bhattacharya.