Why Is Dietary Cholesterol Irrelevant To Most People?
High cholesterol in the blood is a known risk factor for heart disease.
For decades, people have been told that dietary cholesterol raises blood cholesterol levels and causes heart disease.
While this may be a reasonable conclusion based on 50-year-old science, better, more recent evidence does not support it.
This article will detail the current research on dietary cholesterol and its role in blood cholesterol levels and heart disease.
What is cholesterol?
Cholesterol is a waxy, fatty substance that occurs naturally in the body.
Many people believe that cholesterol is harmful, but in fact, it is necessary for the proper functioning of the body.
Cholesterol contributes to the membrane structure of every cell in the body.
The body needs it to produce hormones and vitamin D, as well as to perform a variety of other important functions. Simply put, you can’t live without it.
Your body produces all the cholesterol it needs, but it also absorbs relatively small amounts from certain foods, such as eggs, meat and fatty dairy products.
Cholesterol and lipoproteins
When we talk about cholesterol in relation to heart health, we don’t usually talk about cholesterol itself.
We are referring to lipoproteins – the structures in the blood that carry cholesterol.
Lipoproteins are made up of fat (lipids) on the inside and protein on the outside.
There are many different types of lipoproteins, but the two most important for heart health are low-density lipoproteins (LDL) and high-density lipoproteins (HDL).
Low-density lipoproteins (LDL)
LDL makes up 60-70% of all blood lipoproteins and is responsible for transporting cholesterol particles throughout the body.
It is often referred to as the “bad” cholesterol because it is associated with atherosclerosis or the buildup of plaque in the arteries.
The higher levels of cholesterol carried by LDL are associated with an increased risk of heart disease. In fact, the higher the level, the greater the risk.
There are different types of LDL, classified mainly by size. They are usually classified as small LDL, HDL or large LDL.
Studies have shown that most people with smaller particles have a higher risk of heart disease than people with larger particles.
However, the size of LDL particles is not the most important risk factor; it is their number that matters. This measurement is called the LDL particle count, or LDL-P.
In general, the higher the number of LDL particles, the greater the risk of heart disease.
High-density lipoprotein (HDL)
HDL collects excess cholesterol throughout the body and returns it to the liver, where it is used or excreted.
There is some evidence that HDL can prevent plaque buildup in the arteries.
Cholesterol is often referred to as “good” cholesterol because it is carried by HDL particles, which are associated with a lower risk of heart disease
What effect does dietary cholesterol have on my blood cholesterol?
The amount of cholesterol in your diet and the amount of cholesterol in your blood are two completely different things.
While it would seem logical that eating cholesterol would raise blood cholesterol levels, this is not usually the case.
The body strictly regulates the amount of cholesterol in the blood by controlling the production of cholesterol.
If the amount of cholesterol in the diet decreases, the body produces more cholesterol. The more cholesterol you eat, the less cholesterol your body produces. Therefore, foods with high dietary cholesterol levels have little effect on blood cholesterol levels in most people.
However, for some people, cholesterol-rich foods can raise their blood cholesterol levels. These people makeup about 40% of the population and are often referred to as “super-responders”. This tendency is thought to be genetic.
Dietary cholesterol modestly increases LDL in these individuals but does not appear to increase the risk of heart disease.
This is because the overall increase in LDL particles generally reflects an increase in large LDL particles, rather than small, dense LDL particles. In fact, people with predominantly low-density lipoprotein particles had a lower risk of heart disease.
High responders also have an increase in HDL particles, which compensate for the increase in LDL by carrying excess cholesterol to the liver to be removed from the body.
Thus, although cholesterol levels increase in high responders when dietary cholesterol increases, the ratio of LDL to HDL cholesterol remains the same in these individuals, and their risk of heart disease does not appear to increase.
Of course, there are always exceptions when it comes to nutrition, and some people may see a negative effect from eating foods with high cholesterol.
Cholesterol in the diet and heart disease
Contrary to popular belief, cholesterol is not the only cause of heart disease.
Many factors are involved, including inflammation, oxidative stress, high blood pressure and smoking.
Heart disease is often caused by lipoproteins, including cholesterol, but dietary cholesterol itself has little effect.
However, when cholesterol-rich foods are cooked at high temperatures, oxysterols are produced.
Scientists speculate that high levels of oxysterols in the blood may contribute to the development of heart disease, but more evidence is needed before definitive conclusions can be drawn.
High-quality study finds no link to heart disease
High-quality studies have shown that dietary cholesterol is not associated with an increased risk of heart disease.
In particular, many studies have been conducted on eggs. Although eggs are an important source of dietary cholesterol, several studies have shown that egg consumption is not associated with an increased risk of heart disease.
Eggs may also reduce risk by improving lipoprotein profiles.
One study compared the effects of whole eggs and yolk-free egg replacers on cholesterol levels.
The study found that people who ate three whole eggs per day had a greater increase in HDL particles and a greater decrease in LDL particles than those who ate the same amount of eggs.
However, it is important to note that the consumption of eggs, at least as part of a regular Western diet, may pose a risk to people with diabetes. Some studies have shown that eating eggs increases the risk of heart disease in diabetics.