Fitness Together

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 more recent evidence calls this into question.

High blood cholesterol levels are a known risk factor for heart disease. Whether dietary cholesterol causes them is a different question.

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.

What is cholesterol?

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 essential 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 some 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.

Cholesterol and lipoproteins

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.

Having a lot of cholesterol carried by LDL lipoproteins is associated with an increased risk of heart disease. In fact, the higher the level, the greater the risk.

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.

Some evidence indicates that HDL protects against the buildup of plaque inside your arteries.

It’s often referred to as “good” cholesterol, as having cholesterol carried by HDL particles is associated with a decreased risk of heart disease.

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.

How does dietary cholesterol affect blood cholesterol?

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.

Blood cholesterol levels are mostly determined by the amount of fats and carbohydrates in the diet, not by dietary cholesterol. Recent research has found that for most people, consuming an egg a day had no affect on their cholesterol.

However, in some people, high-cholesterol foods raise blood cholesterol levels. These people are often referred to as “hyperresponders.” This tendency is considered to be genetic.

Even though dietary cholesterol modestly increases LDL in these people, it does not seem to increase their risk of heart disease.

This is because the general increase in LDL particles typically reflects an increase in large LDL particles — not small, dense LDL. In fact, large LDL particles appear not to have any effect on a person’s risk of heart disease.

An older study found that 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 people 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.

Dietary cholesterol and heart disease

Contrary to popular belief, heart disease is not caused only 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 in early studies 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.

Research has found that dietary cholesterol is not associated with an increased risk of heart disease.

A lot of research has been conducted on eggs specifically. Eggs are a significant source of dietary cholesterol, but studies have shown that eating them is not associated with an elevated risk of heart disease.

Also, eggs may even help improve your lipoprotein profiles, which could lower your risk.

One 2013 study compared the effects of whole eggs and a yolk-free egg substitute on cholesterol levels.

People who ate three whole eggs daily 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.

Should you avoid high-cholesterol foods?

Though research is ongoing, and the relationship between dietary and blood cholesterol has proven to be more complex than once thought, there is still no definitive evidence to suggest that there is not a link between high cholesterol foods and heart disease.

The American Heart Association (AHA) does not make conclusive recommendations around dietary cholesterol consumption. Instead, the AHA recommends a focus on healthy foods recommended to lower the risk of heart disease.

The AHA recommends limiting salt and saturated fats, eating more fruits and vegetables, eating more whole grains rich in fiber, low fat dairy products, and protein such as legumes and nuts. It also recommends limiting red meat intake and sugary drinks.

The AHA also recommends staying physically active, doing 150 minutes of moderate exercise or 75 minutes of vigorous exercise weekly to keep your heart healthy.

Many high-cholesterol foods are also among the most nutritious foods you can eat. These include grass-fed beef, whole eggs, full-fat dairy products, fish oil, shellfish, sardines, and liver. Unless your doctor specifically advises you to cut these out of your diet, moderation may be the best approach.

Summary

Many foods that are high in cholesterol are also super nutritious. This includes whole eggs, fish oil, sardines, and liver. However, these should be consumed as part of a healthy program of good nutrition and regular physical activity for the benefits to outweigh the risks.

Ways to lower high blood cholesterol

If you have high cholesterol, you can often lower it through simple lifestyle changes.

For example, losing extra weight may help reverse high cholesterol.

Several studies show that a modest weight loss of 5–10% can lower cholesterol and decrease the risk of heart disease in people with excess weight.

Also, many foods can help lower cholesterol. These include avocados, legumes, nuts, soy foods, fruits, and vegetables.

Adding these foods to your diet can help lower cholesterol and reduce the risk of heart disease.

Being physically active is also important. According to the AHA, exercise improves cholesterol levels and heart health.

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.

The bottom line

The relationship between dietary cholesterol and the cholesterol levels in your body is a complex one. Research on the subject is still not definitive, so you may hear information that seems contradictory. The most important thing to focus on is a balanced diet and exercise.