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Why Dietary Cholesterol Does Not Matter (for most people)
10.12.16, 19)03
Why Dietary Cholesterol Does Not
Matter (for most people)
Kayla McDonell, RD
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 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.
What Is Cholesterol?
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Why Dietary Cholesterol Does Not Matter (for most people)
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Cholesterol is a waxy, fat-like substance that occurs naturally in the human
body.
Many people think of cholesterol as being harmful, but the truth is that it’s
essential for your body to function.
Cholesterol contributes to the membrane structure of every single cell in
your body.
Your body also needs it to make hormones and vitamin D, and 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.
Bottom Line: 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 actually referring to the structures that carry
cholesterol in the bloodstream. These are called lipoproteins.
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).
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Low-Density Lipoprotein (LDL)
LDL makes up 60–70% of total blood lipoproteins and is responsible for
carrying cholesterol particles throughout your body.
It is often referred to as “bad” cholesterol because it has been linked with
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 (1, 2).
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 (3).
Still, the most important risk factor is not the size of LDL particles. It’s the
number. This measurement is called LDL particle number, or LDL-P.
Generally speaking, the higher 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 (4, 5).
It is often referred to as “good” cholesterol because having cholesterol
carried by HDL particles is associated with a decreased risk of heart
disease (6, 7, 8).
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Bottom Line: Lipoproteins are particles that carry cholesterol around
the body. A high level of LDL lipoproteins is associated with a greater
risk of heart disease, whereas higher levels of HDL lipoproteins lower
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.
When your dietary intake of cholesterol goes down, your body makes more.
When you eat larger amounts of cholesterol, your body makes less (9, 10).
Because of this, foods high in dietary cholesterol have very little impact on
blood cholesterol levels in most people (11, 12).
However, in some people, high-cholesterol foods do cause a rise in blood
cholesterol. These people make up about 25% of the population and are
often referred to as “hyperresponders.” This tendency is considered to be
genetic (13, 14).
Even though dietary cholesterol does modestly increase LDL in these
individuals, it does not seem to increase their risk of heart disease (15, 16).
This is because the general increase in LDL particles typically reflects an
increase in large LDL particles, not small, dense LDL. People who have
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mainly large LDL particles actually have a lower risk of heart disease (3).
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 (17).
So even though 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 it is possible that
some individuals see adverse effects from eating more cholesterol-rich
foods.
Bottom Line: Most people can effectively adapt to a higher intake of
cholesterol. Because of this, dietary cholesterol has little effect on blood
cholesterol levels.
Dietary Cholesterol and Heart Disease
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 has little to
no effect on this.
The Myths About Cholesterol Are Based on Bad Research
The original studies that found a relationship between dietary cholesterol
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and heart disease were flawed.
One of the original experiments discovered this link after feeding
cholesterol to rabbits, which are herbivores and do not consume
cholesterol by nature.
Although these results are not relevant to human disease, the study
sparked an increase in clinical studies aiming to demonstrate the same
relationship in people.
Unfortunately, many of the studies that followed were also poorly designed
and researchers selectively excluded information in order to sway results.
Higher-Quality Research Finds no Link With Heart Disease
More recent, higher-quality studies have shown that cholesterol in the diet
is not associated with an increased risk of heart disease (18, 19).
A lot of research has been done 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 (20, 21, 22, 23,
24).
What’s more, eggs may even help improve your lipoprotein profiles, which
could lower your risk.
One study in particular compared the effects of whole eggs and yolk-free
egg substitute on cholesterol levels.
Individuals 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 (25).
However, it is important to note that eating eggs may pose a risk to
diabetics, at least in the context of a regular Western diet. Some studies
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show an increased risk of heart disease in diabetics who eat eggs (26).
Bottom Line: Dietary cholesterol has no link with the risk of heart
disease. High-cholesterol foods like eggs have been shown to be safe
and healthy.
Should You Avoid High-Cholesterol Foods?
For years, people have been told that highcholesterol foods can cause heart disease.
However, the studies mentioned above have
made it clear that this is not the case (9).
It just so happens that many foods high in cholesterol are also among the
healthiest foods on the planet.
These include grass-fed beef, whole eggs, full-fat dairy products, fish oil,
shellfish, sardines and liver.
These foods are incredibly nutritious, so don’t avoid them just because of
their cholesterol content.
Bottom Line: Most foods that are high in cholesterol are also super
healthy and nutritious. This includes whole eggs, fish oil, sardines and
liver.
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
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cholesterol and decrease the risk of heart disease in overweight individuals
(27, 28, 29, 30, 31).
There are also many foods that can help lower cholesterol. These include
avocados, legumes, nuts, soy foods, fruits and vegetables (32, 33, 34, 35).
Adding these foods to your diet can help lower cholesterol and reduce the
risk of heart disease.
Being physically active is also important. Studies have shown that exercise
has positive effects on cholesterol levels and heart health (36, 37, 38).
Bottom Line: High cholesterol can be lowered in many cases through
simple lifestyle changes. Losing extra weight, increasing physical
activity and eating a healthy diet can all help lower cholesterol and
improve heart health.
Take Home Message
High blood cholesterol levels are a risk factor for heart disease.
However, dietary cholesterol has little to no effect on blood cholesterol in
most people.
More importantly, there is no significant link between the cholesterol you
eat and your risk of heart disease.
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