Here’s what cholesterol does to your body

We’re all familiar with cholesterol as a scary term, but what is it? Why do some foods have a lot of it and how does it affect the body?

Here’s everything you should know.

The history of our fixation with cholesterol

People really started paying attention to cholesterol in the 1950s after physiologist Ancel Keys published the “ Seven Countries Study ,” which claimed that heart disease is directly correlated with fat consumption.

“The different age-specific death rates of men 40 to 65 from degenerative heart disease in different countries are directly related to the differences in those countries in the proportion of the total calories derived from total fats,” Keys wrote.

Since its publication, other physiologists have analyzed Keys’ findings, claiming that the “methodology was highly inconsistent across cohorts and thoroughly suspect,” as Russell Smith and Edward Pinckney described in their nearly 850-page review of research published on cholesterol and heart disease.

Smith claimed that Keys’ publication was misleading, as it initially followed 22 countries, but only reported on the few that showed a correlation between fat consumption and death rates.

“It is almost inconceivable that the Seven Countries study was performed with such scientific abandon,” Smith wrote.

So, with the hot debate on whether cholesterol consumption is directly correlated with death, let’s discover what cholesterol actually is and how it affects the body.

What is cholesterol?

Cholesterol naturally occurs in the body and is a waxy, fat-like substance. The body uses cholesterol in many different ways, including cell membrane construction and the production of many hormones (including steroid hormones, sex hormones and vitamin D), according to Harvard Health .

There are two types of cholesterol, neither of which are inherently harmful in their correct amounts.

Low-density lipoproteins: Since fat molecules have a complicated molecular structure, they can’t move through the bloodstream on their own. LDL’s job is to move fat molecules to where they need to go.

However, the Mayo Clinic explains that if LDL levels get too high, they build “up in the walls of your arteries, making them hard and narrow.” This can lead to heart disease and stroke.

High-density lipoproteins: HDL has a higher level of proteins to lipids when compared to LDL. These proteins help transport cholesterol “from the peripheral tissues to the liver,” research published to the National Institutes of Health explains.

Receptors (LDL receptors and SR-B1) and CETP help move LDL to the liver to get broken down and discarded. “CETP exchanges the cholesterol esters in the core of HDL particles” to other proteins, the NIH explains.

Thus, HDL is anti-inflammatory and reduces “the size of plaque” in the arteries.

What does cholesterol do to your body?

Harvard Health explains, “For most people, the amount of cholesterol eaten has only a modest impact on the amount of cholesterol circulating in the blood.”

“Your genetic makeup — not diet — is the driving force behind cholesterol levels,” cardiologist Steven Nissen told Cleveland Clinic .

He continued, “The body creates cholesterol in amounts much larger than what you can eat, so avoiding foods that are high in cholesterol won’t affect your blood cholesterol levels very much.”

Researchers at Harvard University monitored the cholesterol levels of over 80,000 female nurses in a study and concluded that eating an egg every day did not contribute to higher risk of heart disease.

However, the researchers warned that “people who have heart disease or diabetes should monitor egg consumption.” Further, excessive consumption of high-cholesterol foods will eventually raise cholesterol.

Foods naturally high in cholesterol are not the only foods that will raise your cholesterol. Foods with high sugar content increase cholesterol levels as well, cardiologist Romit Bhattacharya explained to Mass General Brigham .

“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,” Bhattacharya said.

What foods cause high cholesterol?

Foods that increase LDL levels are typically high in trans fats and should be avoided, according to the American Heart Association .

Trans fats are commonly created in heavily processed foods when hydrogen is added to seed oils — including vegetable oil. The Mayo Clinic described trans fats as “the worst type of fat to eat.”

Nissen added that foods with high trans fats “often appear on food labels as hydrogenated oils or partially hydrogenated vegetable oil. Those types of fat do tend to raise cholesterol and do tend to increase the risk of heart disease.”

Healthline lists several LDL level-raising foods, naming fried foods, desserts, fast food and processed meats, including hot dogs, bacon and sausage.

The site adds a list of foods high in cholesterol to not worry about if your cholesterol levels are already healthy. These foods include eggs, shellfish, cheese, pasture-raised steak, full-fat yogurt, sardines and organ meats.