Egg yolks almost as bad for your arteries as smoking: study

Jordana Divon
Contributing Writer
Shine On

For all the egg white omelets you've consumed in lieu of their yolkier brethren, a new study published in the Atherosclerosis online journal claims you can also consider it a pack of cigarettes not smoked.

Researchers at Western University in London, Ontario say that when it comes to increasing your risk of heart attack or stroke, eating the round, yellow centre of an egg is almost as bad for you as putting a lit cigarette between your lips and inhaling.

"The problem is, if you expect to live a long time, you are going to be at risk of heart attacks and strokes," Dr. David Spence, a Robarts Research Institute scientist and study co-author, tells QMI Agency. "Why would you want to be eating something that makes the plaque in your arteries build up faster and make your heart attack and stroke come on sooner?"

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Though multiple studies have lauded eggs for their many health benefits, this particular study suggests these benefits appear to be outweighed by potential risks to Canadians of a certain age.

Here's how the researchers reached their controversial conclusion.

Spence and his team gathered data from 1,231 patients at the London Health Sciences Centre. The average patient age was 62.

Scientists took ultrasound measurements of the carotid arteries — this is the artery system that supplies blood and oxygen to the head and neck as well as the brain — to determine the amount of atherosclerotic plaque found inside the small but vital vessels.

Patients also filled out a survey that determined a number of lifestyle factors, such as smoking habits and the frequency of egg yolk consumption.

Researchers quantified their data by multiplying the number of cigarettes smoked per day by the number of years a person smoked. They did the same with the eggs by multiplying the number of eggs per day with the number of years a person ate them.

What researchers found was that after the age of 40, plaque in the carotid arteries increased anyway. But patients who smoked and ate egg yolks experienced an enormous spike in plaque buildup.

And while smoking proved to be the bigger plaque accelerator, egg yolk eaters showed two-thirds of the effect of the smokers group.

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While eating the occasional egg won't do too much damage, the study implies, a constant diet of yolks could potentially lead to major heart problems.

The issue lies in quantity. The recommended daily cholesterol intake for people with heart attack and stroke risk is 200 milligrams.

By contrast, one large egg yolk alone contains 237 milligrams.

However, Spence and his team have some critics. According to Steven Novella of, the study is flawed for a number of reasons.

"The weaknesses of this study includes the fact that it is retrospective and based on survey data, which is notoriously inaccurate. Further, it is an observational study and therefore there are many confounding factors that are not controlled for. Perhaps people who eat more egg yolks also eat more bacon, or have a generally poorer diet, or don't exercise as much."

Novella's criticism also includes that the study's authors have no way to explain a causal relationship between egg consumption and carotid plaque build up in the arteries.

"Apparently what the authors have shown (which is consistent with previous data) is that eating lots of eggs does not increase total cholesterol or bad cholesterol (LDL) nor does it decrease good cholesterol (HDL)...This strongly suggests the association is not causal but is incidental or spurious," writes Novella.

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Other prominent critics include the country's egg farmers.

Karen Harvey, a nutrition officer with the Egg Farmers of Canada, tells QMI that the comparison between cigarettes and eggs is ridiculous.

"It goes without saying that smoking is considered one of the most harmful activities when it comes to your personal health and wellness," Harvey says.

Yolks, she adds, are a nutritious food that contains the major source of the egg's vitamins and minerals.

While nothing beats a hot plate of scrambled eggs and toast on a lazy weekend morning, Canadians with cholesterol issues may want to check out the host of delicious egg white recipes floating around the 'net.

Watch the video below for some details on the health benefit of wine.