Are Whole Eggs and Egg Yolks Good or Bad for You?

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 or orange part, which is rich in nutrients

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

Cholesterol is a waxy substance found in food. 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.

Summary

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 indeed high in cholesterol. In fact, they’re a significant source of cholesterol in the standard American diet.

Two large whole eggs (100 grams) contain about 411 mg of cholesterol (1). By contrast, 100 grams of 30% fat ground beef has about 78 mg of cholesterol (2).

Until 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 Dietary Guidelines for Americans released in December 2015 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.

However, just because a food is high in cholesterol doesn’t necessarily mean it raises cholesterol levels in your blood.

Summary

Two large whole eggs contain 411 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 lifted.

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 produces less cholesterol because more of it is coming from your diet (3, 4).

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

Because of this, blood cholesterol levels don’t change significantly in most people when they eat more cholesterol from foods (4).

In one long-term, well-designed study, consuming egg yolks daily for 1 year did not significantly change total cholesterol, LDL (bad) or HDL cholesterol, or the ratio of total cholesterol to HDL (an important marker of heart disease) in adults with early signs of age-related macular degeneration (5).

However, one review of well-designed studies in healthy individuals found that eating cholesterol-containing foods raised both LDL (bad) and HDL cholesterol, but the ratio of LDL to HDL (an important marker of heart disease risk) remained constant compared with the control group (6).

Likewise, in another study, 30 people who ate 3 eggs per day for 13 weeks had higher total cholesterol, HDL, and LDL (bad) cholesterol compared with those who took only a choline supplement.

However, their HDL to LDL ratio remained the same (7). The study’s authors concluded that eating foods high in cholesterol regulates the amount of cholesterol your body makes in order to maintain the HDL to LDL ratio.

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

• production of vitamin D
• production of steroid hormones like estrogen, progesterone, and testosterone
• production of bile acids, which help digest fat

Last but not least, cholesterol is an essential component of every cell membrane in your body, making it necessary for survival.

Summary

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 slightly while your HDL to LDL ratio remains the same.

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 one to two whole eggs per day doesn’t seem to change cholesterol levels or heart disease risk factors (8, 9, 10, 11).

In one well-designed study, eating two eggs per day did not adversely affect biomarkers of heart disease compared with eating oatmeal (9). Additionally, those who ate eggs for breakfast reported greater satiety than those who ate oatmeal.

Another well-designed study found that eating two eggs per day did not significantly affect total cholesterol, LDL (bad) cholesterol, or glycemic control in people with overweight or obesity who also have prediabetes or diabetes (10).

Another well-designed study looked at the effects of eating eggs on endothelial function in people with heart disease. The endothelium is a membrane that lines your heart and blood vessels.

Eating 2 eggs for breakfast for 6 weeks did not result in differences in cholesterol, flow-mediated dilation (an assessment of vascular function), blood pressure, or body weight compared with eating Egg Beaters or a high carbohydrate breakfast (11).

Eating eggs may also help lower risk of metabolic syndrome.

One large study of adults reported that women who consumed seven eggs per week had lower risk of metabolic syndrome than those who ate one egg per week. (12)

Similarly, another study associated eating four to six eggs per week with decreased risk of metabolic syndrome, compared with eating one egg per month. (13)

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 (14, 15).

One study followed prediabetics 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 (14).

In another study, prediabetic 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 (15).

Although LDL (bad) cholesterol tends to stay the same or increase only slightly when you eat eggs, HDL (good) cholesterol typically increases (14, 16).

In addition, eating omega-3 enriched eggs may help lower triglyceride levels (17, 18).

Research also suggests that eating eggs on a regular basis may be safe for people who already have heart disease. In fact, eating eggs may be associated with fewer cardiac events.

One large study of healthy adults examined peoples’ egg consumption over almost 9 years. Daily egg consumption (less than 1 egg) was associated with a lower risk of cardiovascular disease, ischemic heart disease, and stroke among middle-aged adults. (19)

Another large study found no link between eating eggs and death from coronary heart disease. In men, eating eggs was associated with a lower incidence of death from stroke (20).

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 (21).

Summary

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.

One recent review of studies determined that eating up to seven eggs per week does not significantly increase markers for cardiovascular disease and type 2 diabetes in both people with and without diabetes(22).

However, 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 (23).

A second study in women found an association between high dietary cholesterol intake and increased diabetes risk, but not specifically for eggs (24).

And a large observational study that found no link between eating eggs and heart attacks or strokes did find a 54% increased risk of heart disease when they only looked at people with diabetes (21).

Based on these studies, eggs could be problematic for people living with prediabetes or diabetes.

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 cannot prove that the eggs caused diabetes.

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 nutritious diet may benefit people with diabetes.

In one study, people with diabetes who consumed a high protein, high cholesterol diet containing two eggs per day experienced reductions in fasting blood sugar, insulin, and blood pressure, along with an increase in HDL cholesterol (25).

Other studies link egg consumption with improvements in insulin sensitivity and reduced inflammation in people with prediabetes and diabetes (14, 26).

Summary

Studies on eggs and diabetes provide 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 for most people, it’s been suggested that it may differ for those with certain genetic traits.

However, more research is needed in this area.

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 (27, 28).

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 (29).

A controlled study followed people with typical 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 (30).

However, these people were eating about 3.5 eggs every day for 3 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 typical cholesterol experienced higher blood cholesterol levels in response to a high-cholesterol diet, their bodies began producing less cholesterol to compensate (31).

Familial hypercholesterolemia

A genetic condition known as familial hypercholesterolemia is characterized by very high blood cholesterol levels and an increased risk of heart disease (32).

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 (33, 34).

However, some studies report that LDL and total cholesterol went up significantly in hyper-responders who increased their egg intake, while HDL stayed stable (35, 36).

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 (37).

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 (38).

Summary

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

Eggs are loaded with nutrients

Eggs are a particularly nutrient-rich food. 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: 10% of the daily value (DV)
• Riboflavin: 16% of the DV
• Vitamin B12: 21% of the DV
• Folate: 9% of the DV
• Iron: 5% of the DV
• Selenium: 28% of the DV

Eggs also contain many other nutrients in smaller amounts.

Summary

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 (9, 39, 40).
• Promote weight loss. The high quality protein in eggs increases metabolic rate and can help you lose weight (41, 42, 43).
• Protect brain health. Eggs are an excellent source of choline, which is important for your brain (44, 45, 46).
• Reduce eye disease risk. The lutein and zeaxanthin in eggs help protect against eye diseases like cataracts and macular degeneration (16, 47, 48, 49).
• Decrease inflammation. Eggs may reduce inflammation, which is linked to various health conditions (15, 26).

Summary

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

The bottom line

In general, eggs are a healthy, nutrient-rich food.

For most people, eating eggs does not increase cholesterol levels much. Even when they do, they often increase HDL (good) cholesterol and modify the shape and size of LDL (bad) cholesterol in a way that reduces disease risk.

However, people with certain conditions or genetic predispositions may need to limit their egg intake.