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Are Eggs Really Bad for Your Heart? New Research Helps End the Debate

Are Eggs Really Bad for Your Heart? New Research Helps End the Debate

Americans are eating more eggs than before, but is this trend hurting our health?

More good news for Americans who love their protein-packed eggs: New research suggests that a daily egg habit isn’t bad for your heart.

For the March 2020 study published in BMJ, researchers analyzed data from three previous studies, which followed more than 215,000 men and women for up to 32 years. The people included in the study did not have chronic health issues such as heart disease, type 2 diabetes or cancer when the study began.

The research team found that, overall, eating up to one egg per day isn’t associated with an increased risk for heart disease.

The researchers also noted that most of the people included in these studies reported eating between one and five eggs per week. Those who ate more were also less likely to be treated with cholesterol-lowering drugs, called statins. They also tended to have a higher body mass index (BMI) and eat more red meat—all of which could be associated with higher cholesterol levels.

The ongoing debate
Eggs are loaded with protein, but they’re also one of the richest sources of dietary cholesterol. This is one reason why conventional wisdom on the potential risks and benefits of eating eggs has shifted over the years, resulting in some confusion and concern.

For years, experts advised adults to limit their intake of eggs and other foods high in cholesterol. But in 2015, after decades of warnings, health officials revised the Dietary Guidelines for Americans, omitting the previous recommendation to limit dietary cholesterol intake to 300 milligrams (mg) per day. The decision was based on mounting scientific evidence suggesting that genetics and saturated fat have a much greater effect on blood cholesterol levels than cholesterol in food.

Since then, egg consumption among Americans increased. But in March 2019, Americans’ love affair with omelets was challenged once again. A study from Northwestern University published in JAMA found that higher egg and cholesterol consumption was associated with increased risk for heart disease and death. The study’s authors argued that their findings should prompt a review of the 2015 dietary guidelines on cholesterol, which set no limits on daily dietary cholesterol intake.

So, while the pendulum of generally accepted nutritional wisdom has swung from one extreme (eggs are high in cholesterol and bad for your heart) to the other (the dietary cholesterol in eggs won’t significantly increase the risk for heart disease in otherwise healthy people), it now appears that the takeaway on eggs isn’t about one extreme or the other. Like many things in life, moderation is key.

Eggs can likely be a part of a healthy diet for many people, according to Keith Roach, MD, associate professor in clinical medicine in the division of general medicine at Weill Cornell Medical College and New York Presbyterian Hospital.

What’s good and what’s not so good
An egg is a low-calorie, low-carbohydrate nutrient powerhouse. One large egg contains only about 70 calories, but it’s got a whopping 6 grams of protein. It’s also rich in good stuff like vitamin D, vitamin B12, choline, lutein and zeaxanthin, supporting your bones, liver and vision. (Some eggs are also enriched with beneficial omega-3 fatty acids.)

One large egg has nearly 5 grams of fat—including 8 percent of the recommended Daily Value (DV) of saturated fat—but most of the fat in eggs is actually the good kind (monounsaturated and polyunsaturated). The bigger issue is that it also contains about 186 mg of cholesterol.

The body packages fat and cholesterol into particles called lipoproteins. The “bad” ones, known as LDL cholesterol (low-density lipoproteins) can build up in the arteries, potentially limiting blood flow. This increases the risk for heart attack and stroke. It seems logical, therefore, that reducing intake of dietary cholesterol would help protect the heart. And for years, that was the recommendation.

Why the egg debate continues
Though the 2015 Dietary Guidelines’ omission of dietary cholesterol as a nutrient of concern kicked off an egg-eating spree, the 2019 Northwestern study called this dietary habit back into question.

The researchers examined pooled data on a diverse group of 29,615 U.S. adults from six different studies. Information on the participants’ diets was collected at one point in time (so even if someone’s diet changed, they were still considered “egg eaters.”) The people were followed for up to 31 years to track how their diet and egg consumption, in particular, affected their heart health.

The study found that consuming 300 mg of dietary cholesterol per day was linked to a 17 percent higher risk of heart disease and an 18 percent higher risk of death. Eating three to four eggs on a weekly basis was associated with a 6 percent higher risk of heart disease and an 8 percent higher risk of death from any cause. The main driving factor, the researchers noted, was cholesterol in particular—not saturated fat intake or other forms of dietary fat.

Don’t sell the chicken coop just yet
The Northwestern study was well-designed, but “the absolute increase in heart disease and mortality risk was modest,” Roach points out.

Interestingly, the authors of the March 2020 BMJ study pointed out that the findings of the Northwestern team could be attributed to certain confounding factors, such as participants’ body mass index. They pointed out that their analysis included that 2019 study—and they still did not find that eating one egg per day was associated with an increased for heart disease. 

It’s also important to remember that despite the ongoing egg debate, the Dietary Guidelines haven’t changed—at least not yet.

So, what’s right for you?
The American Heart Association (AHA) has long advised that most healthy adults could safely have one egg day as part of a healthy diet. Having one egg per day, or no more than seven per week, while limiting other foods high in dietary cholesterol, remains a smart strategy, Roach advises.

So, if you’re otherwise healthy and rarely or never eat foods high in saturated fat, you can probably incorporate eggs into an overall heart-healthy diet that emphasizes a wide variety of fruits, vegetables and whole grains. If your LDL or “bad” cholesterol level is low (or less than 70 without medication) then you don’t need to worry about it, adds Roach.

That said, there are some variables to consider when deciding what to have for breakfast. For example, high cholesterol tends to run in families. If your parents or close relatives were diagnosed with the condition, it’s more likely to affect you, which may limit some of your food choices.

Those who already have high cholesterol or have an inherited genetic condition called familial hypercholesterolemia (FH), which causes them to have very high LDL cholesterol levels at a young age that worsen over time, should avoid eggs or more carefully limit their dietary cholesterol consumption.

People with certain conditions that increase the risk for high cholesterol and heart disease, including obesity and type 2 diabetes, may also need to more strictly limit their egg intake.

Cholesterol levels tend to increase with age, Roach points out. So, as you get older, you may want to be more mindful about how many eggs you’re eating. If you smoke, are not active or are overweight, you’re at greater risk for high cholesterol levels. So, limiting your egg intake in these cases may be a good idea.

It’s also important to consider your overall diet. You may need to be careful about how many eggs you’re eating, but they’re likely still a healthier option than many sugary cereals, pancakes drenched in syrup or a buttered bagel, which may have fewer nutrients but a lot of “empty calories,” which can lead to weight gain and a reduction in your heart health. Red or processed meat and whole milk dairy products also contain saturated fat, which is a known contributor to high cholesterol levels.

Know your numbers
It’s important to talk to your doctor about your diet and your risk factors for heart disease and high cholesterol to determine what’s right for you. A registered dietitian could also help you incorporate eggs into your diet in a healthy way (hint: don’t cook them in bacon grease).

Another way to curb your egg habit is to opt for just the whites sometimes. Egg whites are high in protein but not cholesterol (the cholesterol is in the yolk).

Being aware of your cholesterol levels can help you make wise decisions about your diet and protect your long-term health.

Adults age 20-years or older should have their cholesterol checked every 4 to 6 years, according to the AHA. If you have heart disease or risk factors for heart disease, you may need more frequent screenings. Your doctor can help you understand what your cholesterol levels mean and whether or not you would benefit from certain lifestyle adjustments, cholesterol-lowering medications or other treatment options.

Medically reviewed in March 2019. Updated in March 2020.

Sources:
JP Drouin-Chartier, S Chen, et al. “Egg consumption and risk of cardiovascular disease: three large prospective US cohort studies, systematic review, and updated meta-analysis.” BMJ. 2020; 368 :m513.
U.S. Department of Health and Human Services. “Dietary Guidelines for Americans: 2015-2020.”
U.S. Department of Agriculture. “Food Data: Egg.”
Harvard T.H. Chan School of Public Health. “The Nutrition Source: Egg,” “The Nutrition Source: Cholesterol,” “Eggs and cholesterol back in the spotlight in new JAMA study.”
EurekAlert. “Bad news for egg lovers.” March 15, 2019.
Centers for Disease Control and Prevention. “Knowing Your Risk for High Cholesterol.”
American Heart Association. “Added Sugars.” “Are eggs good for you or not?” “How to Get Your Cholesterol Tested.”

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