In recent decades the egg, like Humpty Dumpty, has had a great fall. Since the mid-1940s, concern about cholesterol and heart disease has sent per capita consumption plummeting from more than 400 eggs a year to only 235 in 1992, according to the latest figures available.
But after a half-century of hard knocks, 1995 may be the year that the egg, unlike Humpty, gets put together again.
After three decades of blanket dietary advice to keep daily cholesterol intake below 300 milligrams and to limit egg consumption to four yolks a week, some experts on diet and heart disease are considering a more individualized approach that would allow a large portion of the population to eat more eggs, as well as other foods, like shrimp, that are relatively high in cholesterol but low in fat.
The interest in eggs stems from several incontrovertible facts. Eggs are inexpensive, readily available, easy to chew and digest, simple to prepare, relatively low in calories, and rich in protein, iron and many other essential nutrients.
Unfortunately, eggs are also rich in cholesterol. The yolk of one large egg (the whites are free of both fat and cholesterol) has 213 milligrams of cholesterol and 5 grams of fat; 2 of them are saturated fat, which can raise blood levels of cholesterol.
Cholesterol in the diet became a health issue after studies of thousands of people in a dozen countries showed a direct link between the amount of cholesterol in the blood and the risk of developing and dying of coronary heart disease. However, subsequent research revealed two main influences on blood cholesterol: the amount of saturated fat in the diet and heredity.
Dietary cholesterol is only weakly associated with coronary risk. For the average American, eating an additional 200 milligrams of cholesterol a day (about the amount in one egg) raises blood cholesterol about 3 milligrams, which in turn raises the risk of coronary disease by 6 percent.
But people are not averages. There are several ways in which the body can compensate for an increase in dietary cholesterol. In most people, cholesterol production in the liver is reduced in direct proportion to the amount consumed. In addition, excretion of cholesterol through the production of bile acids often rises as more cholesterol is eaten. And when a lot of cholesterol is consumed at once, absorption through the digestive tract commonly drops. Genetically, people fall into three groups: those who are very sensitive to dietary cholesterol and whose blood levels rise significantly when they eat more cholesterol; those who are insensitive and whose blood levels remain the same or even fall when more cholesterol is consumed, and those in between.
Researchers at Bowman Gray School of Medicine in WinstonSalem, N.C., recently identified a common genetic mutation that makes people resistant to dietary cholesterol, allowing them to eat 1,000 milligrams a day without raising their blood levels.
To add to the confusion, in healthy adults, daily egg consumption has been shown to raise blood levels of the so-called good cholesterol, highdensity lipoprotein or HDL cholesterol, which helps to keep blood vessels free of cholesterol deposits.
Experts estimate that about onethird of Americans fall into the highresponse group, the ones who should be most concerned about limiting dietary cholesterol to 300 milligrams or less each day.
“We’re now at a point where we can be a little more targeted in making dietary recommendations,” said Dr. Wayne Callaway, a specialist in metabolism and nutrition at George Washington University in Washington, D.C. “Those with a family history of early heart disease or high cholesterol are the ones who most need preventive dietary advice.”
MEMO: See sidebar that ran with this story under the headline: You can make your eggs healthy
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