High blood cholesterol levels are a known risk factor for heart disease.
For decades, people have been told that the dietary cholesterol in foods raises blood cholesterol levels and causes heart disease.
This idea may have been a rational conclusion based on the available science 50 years ago, but better, more recent evidence doesn't support it.
This article takes a close look at the current research on dietary cholesterol and the role it plays in blood cholesterol levels and heart disease.
Cholesterol is a waxy, fat-like substance that occurs naturally in your body.
Many people think that cholesterol is harmful, but the truth is that it's essential for your body to function.
Cholesterol contributes to the membrane structure of every cell in your body.
Your body also needs it to make hormones and vitamin D, as well as perform various other important functions. Simply put, you could not survive without it.
Your body makes all the cholesterol it needs, but it also absorbs a relatively small amount of cholesterol from certain foods, such as eggs, meat, and full-fat dairy products.
Summary Cholesterol is a waxy, fat-like substance that humans need to survive. Your body makes cholesterol and absorbs it from the foods you eat.
When people talk about cholesterol in relation to heart health, they usually aren't talking about cholesterol itself.
They are referring to lipoproteins — the structures that carry cholesterol in the bloodstream.
Lipoproteins are made of fat (lipid) on the inside and protein on the outside.
There are several kinds of lipoproteins, but the two most relevant to heart health are low-density lipoprotein (LDL) and high-density lipoprotein (HDL).
Low-density lipoprotein (LDL)
LDL comprises 60–70% of total blood lipoproteins and is responsible for carrying cholesterol particles throughout your body.
It’s often referred to as "bad" cholesterol, as it has been linked to atherosclerosis, or the buildup of plaque in arteries.
There are different types of LDL, mainly broken down by size. They are often classified as either small, dense LDL or large LDL.
Studies show that people who have mostly small particles are at a greater risk of developing heart disease than those with mostly large particles (
Still, the size of LDL particles is not the most important risk factor — it's the number of them. This measurement is called LDL particle number, or LDL-P.
Generally, the higher the number of LDL particles you have, the greater your risk of developing heart disease.
High-density lipoprotein (HDL)
HDL picks up excess cholesterol throughout your body and takes it back to your liver, where it can be used or excreted.
Summary Lipoproteins are particles that carry cholesterol around your body. A high level of LDL lipoproteins is associated with a greater risk of heart disease, whereas a high level of HDL lipoproteins lowers your risk.
The amount of cholesterol in your diet and the amount of cholesterol in your blood are very different things.
Although it may seem logical that eating cholesterol would raise blood cholesterol levels, it usually doesn't work that way.
The body tightly regulates the amount of cholesterol in the blood by controlling its production of cholesterol.
When your dietary intake of cholesterol goes down, your body makes more. When you eat greater amounts of cholesterol, your body makes less. Because of this, foods high in dietary cholesterol have very little impact on blood cholesterol levels in most people (
However, in some people, high-cholesterol foods raise blood cholesterol levels. These people make up about 40% of the population and are often referred to as "hyperresponders." This tendency is considered to be genetic (
This is because the general increase in LDL particles typically reflects an increase in large LDL particles — not small, dense LDL. In fact, people who have mainly large LDL particles have a lower risk of heart disease (
Hyperresponders also experience an increase in HDL particles, which offsets the increase in LDL by transporting excess cholesterol back to the liver for elimination from the body (
As such, while hyperresponders experience raised cholesterol levels when they increase their dietary cholesterol, the ratio of LDL to HDL cholesterol in these individuals stays the same and their risk of heart disease doesn't seem to go up.
Of course, there are always exceptions in nutrition, and some individuals may see adverse effects from eating more cholesterol-rich foods.
Summary Most people can adapt to a higher intake of cholesterol. Thus, dietary cholesterol has little effect on blood cholesterol levels.
Contrary to popular belief, heart disease is not only caused by cholesterol.
Many factors are involved in the disease, including inflammation, oxidative stress, high blood pressure, and smoking.
While heart disease is often driven by the lipoproteins that carry cholesterol around, dietary cholesterol, in itself, has little to no effect on this.
However, high-heat cooking of cholesterol-rich foods can cause the formation of oxysterols (
Scientists have hypothesized that high blood levels of oxysterols may contribute to the development of heart disease, but further evidence is needed before any strong conclusions can be reached (
High-quality research finds no link to heart disease
A lot of research has been conducted on eggs specifically. Eggs are a significant source of dietary cholesterol, but several studies have shown that eating them is not associated with an elevated risk of heart disease (
What's more, eggs may even help improve your lipoprotein profiles, which could lower your risk.
One study compared the effects of whole eggs and a yolk-free egg substitute on cholesterol levels.
People who ate three whole eggs per day experienced a greater increase in HDL particles and a greater decrease in LDL particles than those who consumed an equivalent amount of egg substitute (
However, it’s important to note that eating eggs may pose a risk for those with diabetes, at least in the context of a regular Western diet. Some studies show an increased risk of heart disease in people with diabetes who eat eggs (
Summary Dietary cholesterol is not linked to the risk of heart disease. High-cholesterol foods like eggs have been shown to be safe and healthy.
For years, people have been told that a high intake of cholesterol can cause heart disease.
However, the studies mentioned above have made it clear that this is not the case (
Many high-cholesterol foods are also among the most nutritious foods on the planet.
These include grass-fed beef, whole eggs, full-fat dairy products, fish oil, shellfish, sardines, and liver.
Many of these foods are also high in saturated fat. Studies suggest that replacing dietary saturated fat with polyunsaturated fat reduces the risk of heart disease (
The potential role of saturated fat in the development of heart disease is otherwise controversial (
Summary Most foods that are high in cholesterol are also super nutritious. This includes whole eggs, fish oil, sardines, and liver.
If you have high cholesterol, you can often lower it through simple lifestyle changes.
For example, losing extra weight may help reverse high cholesterol.
Adding these foods to your diet can help lower cholesterol and reduce the risk of heart disease.
Summary In many cases, high cholesterol can be lowered by making simple lifestyle changes. Losing extra weight, increasing physical activity, and eating a healthy diet can all help lower cholesterol and improve heart health.
High blood cholesterol levels are a risk factor for heart disease.
However, dietary cholesterol has little to no effect on blood cholesterol levels in most people.
More importantly, there is no significant link between the cholesterol you eat and your risk of heart disease.