Egg Yolks, Cholesterol and Heart Disease: What you Need to Know

This article was originally published by our friends at Authority Nutrition.

Depending on who you ask, whole eggs are either healthy or unhealthy.

On one hand, they’re considered an excellent and inexpensive source of protein and various nutrients.

On the other hand, many people believe that the yolks can increase heart disease risk.

So are eggs good or bad for your health? This article explores both sides of the argument.

Why Are Eggs Sometimes Considered Unhealthy?

Whole eggs have two main components:

  • Egg white: The white part, which is mostly protein.
  • Egg yolk: The yellow/orange part, which contains all sorts of nutrients.

The main reason eggs were considered to be unhealthy in the past, is that the yolks are high in cholesterol.

Cholesterol is a waxy substance found in food, and it’s also made by your body. A few decades ago, large studies linked high blood cholesterol to heart disease.

In 1961, the American Heart Association recommended limiting dietary cholesterol. Many other international health organizations did the same.

Over the next several decades, worldwide egg consumption decreased significantly. Many people replaced eggs with cholesterol-free egg substitutes that were promoted as a healthier option.

Bottom Line: For several decades, eggs were believed to increase heart disease risk because of their high cholesterol content.

It’s True That Whole Eggs Are High in Cholesterol


Whole eggs (with the yolks) are undeniably high in cholesterol. In fact, they’re the major source of cholesterol in most people’s diets.

Two large whole eggs (100 grams) contain about 422 mg of cholesterol (1).

By contrast, 100 grams of 30% fat ground beef has only about 88 mg of cholesterol (2).

Up until very recently, the recommended maximum daily intake of cholesterol was 300 mg per day. It was even lower for people with heart disease.

However, based on the latest research, health organizations in many countries no longer recommend restricting cholesterol intake.

For the first time in decades, the US Dietary Guidelines released in January 2016 did not specify an upper daily limit for dietary cholesterol.

Despite this change, many people remain concerned about consuming eggs.

This is because they’ve been conditioned to associate high dietary cholesterol intake with high blood cholesterol and heart disease.

That being said, just because a food is high in cholesterol, it doesn’t necessarily raise cholesterol levels in the blood.

Bottom Line: Two large whole eggs contain 422 mg of cholesterol, which exceeds the maximum daily limit that was in place for many decades. However, this restriction on dietary cholesterol has now been removed.

How Eating Eggs Affects Blood Cholesterol


Although it may seem logical that dietary cholesterol would raise blood cholesterol levels, it usually doesn’t work that way.

Your liver actually produces cholesterol in large amounts, because cholesterol is a necessary nutrient for your cells.

When you eat larger amounts of high-cholesterol foods such as eggs, your liver simply starts producing less cholesterol (3, 4).

Conversely, when you get little cholesterol from food, your liver produces more.

Because of this, blood cholesterol levels don’t change significantly in most people when they eat more cholesterol from foods (5).

Also, let’s keep in mind that cholesterol isn’t a “bad” substance. It is actually involved in various processes in the body, such as:

Last but not least, cholesterol is found in every single cell membrane in your body. Without it, humans wouldn’t exist.

Bottom Line: When you eat eggs or other cholesterol-rich foods, your liver produces less cholesterol. As a result, your blood cholesterol levels will likely stay about the same or increase only slightly.

Do Eggs Increase Heart Disease Risk?


Several controlled studies have examined how eggs affect heart disease risk factors. The findings are mostly positive or neutral.

Studies show that eating 1–2 whole eggs per day doesn’t seem to change cholesterol levels or heart disease risk factors (6, 7, 8).

What’s more, consuming eggs as part of a low-carb diet improves markers of heart disease in people with insulin resistance or type 2 diabetes. This includes the size and shape of LDL particles (9, 10, 11).

One study followed pre-diabetics who were on a carb-restricted diet. Those who consumed whole eggs experienced better insulin sensitivity and greater improvements in heart health markers than those who ate egg whites (10).

In another study, pre-diabetic people on low-carb diets ate 3 eggs per day for 12 weeks. They had fewer inflammatory markers than those who consumed an egg substitute on an otherwise identical diet (11).

Although LDL (“bad”) cholesterol tends to stay the same or increase only slightly when you eat eggs, HDL (“good”) cholesterol typically increases (10, 12, 13).

In addition, eating omega-3 enriched eggs may help lower triglyceride levels (14, 15).

Research also suggests that eating eggs on a regular basis may be safe for people who already have heart disease.

One study followed 32 people with heart disease. They experienced no negative effects on heart health after consuming 2 whole eggs every day for 12 weeks (16).

To top things off, a review of 17 observational studies with a total of 263,938 people found no association between egg consumption and heart disease or stroke (17).

Bottom Line: Studies have shown that egg consumption generally has beneficial or neutral effects on heart disease risk.

Do Eggs Increase Diabetes Risk?


Controlled studies show that eggs may improve insulin sensitivity and reduce heart disease risk factors in people with prediabetes.

However, there is conflicting research on egg consumption and the risk of type 2 diabetes.

A review of two studies involving more than 50,000 adults found that those consuming at least one egg daily were more likely to develop type 2 diabetes than people who ate less than one egg per week (18).

A second study in women found an association between high dietary cholesterol intake and increased diabetes risk, but not specifically for eggs (19).

The large observational study mentioned above that found no link between heart attacks and strokes did actually find a 54% increased risk of heart disease when they only looked at people with diabetes (17).

Based on these studies, eggs could be problematic for people who are diabetic or pre-diabetic.

However, it’s important to keep in mind that these are observational studies based on self-reported food intake.

They only show an association between egg consumption and an increased likelihood of developing diabetes, these types of studies can not prove that the eggs caused anything.

In addition, these studies don’t tell us what else the people who developed diabetes were eating, how much exercise they did or what other risk factors they had.

In fact, controlled studies have found that eating eggs along with a healthy diet may benefit people with diabetes.

In one study, people with diabetes who consumed a high-protein, high-cholesterol diet containing 2 eggs per day experienced reductions in fasting blood sugar, insulin and blood pressure, along with an increase in HDL cholesterol (20).

Other studies link egg consumption with improvements in insulin sensitivity and reduced inflammation in people with prediabetes and diabetes (10, 21).

Bottom Line: The studies on eggs and diabetes have mixed results. Several observational studies show an increased risk of type 2 diabetes, while controlled trials show an improvement in various health markers.

Your Genes May Affect How You Respond to Egg Consumption


Although eggs pose no risk to health in most people, it’s been suggested that those with certain genetic traits may be different.

However, there isn’t a lot of research on this.

The ApoE4 Gene

People who carry a gene known as ApoE4 have an increased risk of high cholesterol, heart disease, type 2 diabetes and Alzheimer’s disease (22, 23).

An observational study of more than 1,000 men found no association between high egg or cholesterol intake and heart disease risk in ApoE4 carriers (24).

A controlled study followed people with normal cholesterol levels. A high egg intake, or 750 mg of cholesterol per day, increased total and LDL cholesterol levels in ApoE4 carriers more than twice as much as in people without the gene (25).

However, these people were eating about 3.5 eggs every day for three weeks. It’s possible that eating 1 or 2 eggs may have caused less dramatic changes.

It’s also possible that the increased cholesterol levels in response to high egg intake are temporary.

One study found that when ApoE4 carriers with normal cholesterol experienced higher blood cholesterol levels in response to a high-cholesterol diet, their bodies began producing less cholesterol to compensate (26).

Familial Hypercholesterolemia

A genetic condition known as familial hypercholesterolemia is characterized by very high blood cholesterol levels and an increased risk of heart disease (27).

According to experts, reducing cholesterol levels is very important for people with this condition. It often requires a combination of diet and medication.

People with familial hypercholesterolemia may need to avoid eggs.

Dietary Cholesterol Hyper-Responders

A number of people are considered “hyper-responders” to dietary cholesterol. This means that their blood cholesterol levels increase when they eat more cholesterol.

Often both HDL and LDL cholesterol levels increase in this group of people when they consume eggs or other high-cholesterol foods (28, 29).

However, some studies report that LDL and total cholesterol went up significantly in hyper-responders who increased their egg intake, but HDL was stable (30, 31).

On the other hand, a group of hyper-responders consuming 3 eggs per day for 30 days mainly had an increase in large LDL particles, which are not considered as harmful as small LDL particles (32).

What’s more, hyper-responders may absorb more of the antioxidants located in the yellow pigment of egg yolk. These can benefit eye and heart health (33).

Bottom Line: People with certain genetic traits may see a greater rise in their cholesterol levels after eating eggs.

Eggs Are Loaded with Nutrients


Eggs also have a ton of nutrients and health benefits that need to be mentioned when considering the health effects of eggs.

They are a great source of high-quality protein, as well as several important vitamins and minerals.

One large whole egg contains (1):

  • Calories: 72.
  • Protein: 6 grams.
  • Vitamin A: 5% of the RDI.
  • Riboflavin: 14% of the RDI.
  • Vitamin B12: 11% of the RDI.
  • Folate: 6% of the RDI.
  • Iron: 5% of the RDI.
  • Selenium: 23% of the RDI.

Then there are many other nutrients in there in smaller amounts. In fact, eggs contain a little bit of almost everything the human body needs.

Bottom Line: Eggs are high in a number of important vitamins and minerals, along with high-quality protein.

Eggs Have Many Health Benefits

Studies show that eating eggs can have various health benefits. These include:

  • Help keep you full: Several studies show that eggs promote fullness and help control hunger so you eat less at your next meal (34, 35, 36).
  • Promote weight loss: The high-quality protein in eggs increases metabolic rate and can help you lose weight (37, 38, 39).
  • Protect brain health: Eggs are an excellent source of choline, which is important for your brain (40, 41).
  • Reduce eye disease risk: The lutein and zeaxanthin in eggs help protect against the eye diseases cataracts and macular degeneration (13, 42, 43).
  • Decrease inflammation: Eggs may reduce inflammation, which is linked to various diseases (11, 20).

Bottom Line: Eggs help you stay full, may promote weight loss and help protect your brain and eyes. They may also reduce inflammation.

Eggs Are Super Healthy (for Most People)

In general, eggs are one of the healthiest and most nutritious foods you can eat.

In most cases, they do not increase cholesterol levels much. Even when they do, they often increase HDL (the “good”) cholesterol and modify the shape and size of LDL in a way that reduces disease risk.

However, as with most things in nutrition, this may not apply to everyone and some people may need to limit their egg intake.

Kris Gunnars is a medical student, personal trainer and someone who has spent years reading books, blogs and research studies on health and nutrition. Kris believes that there is an immense amount of evidence that runs completely contradictory to what the governments and dietitians around the world are recommending. Since starting medical school and becoming a personal trainer, he's learned that the textbooks on nutrition that our future doctors and health authorities read are based on that same faulty or nonexistent evidence. Kris' goal is change that! For more from Kris- Subscribe to Free Updates from his website or click the links above to follow him on Facebook or Twitter.