Egg Yolks Almost as Bad for Arteries as Smoking
But industry and some health experts say the food may not be so dangerous.
"People at risk of vascular disease should not eat egg
yolks," contends study lead author Dr. David Spence, professor of
neurology at Western University in London, Ontario, Canada.
The cholesterol found in an egg's yellow center can even clog the carotid artery
leading to the brain, upping risks for stroke, he pointed out.
"Carotid plaque goes up steeply with age, so the only people who
can eat egg yolks with impunity are those who know they will die young from
some cause other than vascular disease," Spence said.
The report was published online this month in Atherosclerosis.
For the study, Spence's team collected data on more than 1,200 men and
women who were taking part in an initiative aimed at curbing heart
disease.
The researchers used ultrasound to first determine the amount of
plaque in each patient's arteries. They then asked patients about smoking,
their frequency of eating eggs, other lifestyle factors and any medicines they
were taking.
Although artery plaque levels rose with age, both smoking and eating
egg yolks sped up this plaque formation within vessels, the researchers found.
Regular consumption of egg yolks sped up plaque deposits in arteries at a rate
that was about two-thirds the rate seen with smoking, Spence said.
People who ate three or more yolks a week had significantly increased
plaque compared with people who ate two or fewer yolks a week, the team found.
That makes sense, Spence said, since just "one egg yolk contains more than
the recommended daily intake of cholesterol."
An expert not connected to the study agreed. According to Samantha
Heller, clinical nutrition coordinator at the Center for Cancer Care at Griffin
Hospital in Derby, Conn., "it is known that the amount of cholesterol in
many egg yolks is more than the recommended 200 milligrams per day for people
with risk factors for cardiovascular disease."
The study authors noted that the effect of egg
yolks on plaque was independent of the person's sex, cholesterol
levels, blood pressure, smoking, weight and diabetes.
In a statement, the American Egg Board said that the findings come
from "an observational study that can only suggest potential
relationships, not determine actual cause-and-effect
conclusions."
The Egg Board also noted in the statement that "study subjects
with higher egg intakes tended to also be heavy smokers, and only a small
percentage of the population consumed more than five eggs per week, meaning
that the conclusions were based on a small number of subjects."
Dr. Gregg Fonarow, a spokesman for the American Heart Association and
professor of cardiology at the University of California, Los Angeles, said the
evidence for and against egg yolk consumption has see-sawed for
decades.
"Whether dietary egg consumption is associated with an increased
risk of cardiovascular disease has been controversial and previous studies have
been inconsistent," Fonarow said. He said the jury remains out on the
issue, pending further study.
Right now, Fonarow said, "the American Heart Association recommends
for maintaining heart and brain health to eat a variety of nutritious food from
all the food groups, with emphasis on vegetables, fruits, whole-grain products
and fat-free or low-fat dairy products as well as eating fish at least twice a
week."
Heller stressed, though, that cholesterol lurks in many foods,
including meat and cheese, and foods that are made with eggs, such as baked
goods.
She wondered if the study might be targeting egg yolks and missing
some of these other sources of cholesterol.
"Most animal foods also contain saturated fat, which increases
internal inflammation and serum [blood] cholesterol," Heller noted.
"The study does not take into account other foods that contain
cholesterol, saturated fat or egg yolks. Could it be that people who eat a lot
of eggs also combine them with other less healthy foods such as cheese or
sausage?"
The Egg Board agreed. "The study did not control for exercise
habits, waist circumference, intake of saturated fat, alcohol or foods commonly
eaten with eggs like high-fat meats and other high-fat side dishes," it
said in the statement.
On the other hand, egg whites remain an excellent
source of protein and a great alternative to the whole egg, Heller
said.
"Though some people complain that egg whites do not taste as good
as the whole egg, adding vegetables like spinach, onions or mushrooms, herbs
and a pinch of turmeric to make the egg whites yellow — the visual
seems to make a difference here — can create a delicious and healthy
meal," Heller said.
Research suggests a more plant-based diet — which means
eating fewer eggs, less cheese, red and processed meats, and more vegetables,
beans, nuts and fruits — may improve risk factors for cardiovascular
disease such as high cholesterol, blood pressure and triglycerides, she added.
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