They said it couldn't be done. But the cholesterol-burdened egg, which fell from grace 30 years ago after being labeled a health risk, is putting its reputation back together again.
Per capita egg consumption is on the rebound nationwide -- up in each of the past three years. These increases have come as researchers report that dietary cholesterol from eggs and other foods may not be as worrisome as earlier believed. They also come as specialty "designer eggs" -- that are high in heart-healthy Omega-3 fatty acids and other nutrients -- are expanding the market.
The future may be even better. The American Heart Association (AHA), which led the charge against egg consumption during the 1970s and 1980s, is in the early stages of reviewing its influential recommendation that people limit their consumption of egg yolks to no more than three to four a week.
"Will we be telling people to eat as many eggs as they want? No, we will not," said Robert Eckel, chairman of the AHA nutrition committee and a physician at the University of Colorado Health Sciences Center. "But we are open to the new information and new data out there, and we will not be afraid to change our recommendations if that's what's called for."
An advocate of the egg's rehabilitation is Donald McNamara, executive director of the Egg Nutrition Center, an arm of the American Egg Board. He traveled to Dallas last month to address some members of the AHA nutrition committee and its staff.
"I think there is a real openness to look at and reevaluate the issue," McNamara said after his meeting. "The egg was demonized for years, became a kind of icon of what was supposedly wrong with the American diet. What we're saying is that the data just doesn't support that negative conclusion."
The AHA nutrition committee will meet tomorrow to discuss updated nutrition guidelines for eggs and other foods. The 22-person committee will then make recommendations to the AHA board for the final guidelines.
The new AHA guidelines are expected to be released early next year.
A Golden Past
Once the egg was as wholesomely American as apple pie. Two eggs contain 20 percent of the recommended daily requirement of protein plus enviable concentrations of important nutrients such as vitamin B12, vitamin D, riboflavin and folate. What's more, eggs are an inexpensive source of these nutrients and deliver them in a relatively low calorie package--an important issue at a time when the Centers for Disease Control and Prevention reports that overweight is "epidemic" in the United States. Two eggs contain 140 calories, about the same amount as a can of Coke.
But egg yolks are also high in cholesterol, a fat-like substance found in all cell membranes. A single egg averages 215 milligrams of cholesterol, or 71 percent of the daily intake recommended by the government's nutrition guidelines.
It was research into the relationship between high levels of cholesterol in the diet and cardiovascular disease that toppled the egg three decades ago. And it is research into that same relationship that is helping to restore it today.
In the late 1960s and 1970s, researchers concluded that men and women who ate diets high in cholesterol had a significantly increased risk of heart disease. Since eggs are high in cholesterol, the AHA and others recommended that egg consumption be limited. Seldom has a major food industry seen such a dramatic collapse: Per capita egg consumption fell from 320 a year in 1967 to a low of 233 a year in 1991, according to the U.S. Department of Agriculture.
Researchers say that the link between high cholesterol levels in the blood and heart disease remains strong. They also say that diets high in saturated fats--primarily fats from meat products and cheeses--have been conclusively shown to cause unhealthy cholesterol levels in the blood.
But the link between heart disease and cholesterol from the diet, and particularly from eggs and shellfish, has been progressively weakened. Researchers have found that individuals respond quite differently to cholesterol in their diets, and that only 15 to 25 percent of Americans have significant difficulty readjusting their blood cholesterol levels after eating foods high in cholesterol.
That means a majority of Americans will slow down production of cholesterol in their livers--which normally manufacture cholesterol at a rate of about 1,000 milligrams per day--when they are already getting enough from the diet. This self-regulation limits the negative effect of dietary cholesterol, researchers say. Genetic factors and body weight appear to play major roles in determining who can regulate cholesterol well and who cannot.
Statistics on international egg consumption and cardiovascular disease suggest how complicated the relationship between dietary cholesterol and cardiac disease may be. According to the Egg Nutrition Center, four of the nations with the highest rates of egg consumption are Japan, Mexico, Spain and France. Yet AHA statistics show that the four have among the lowest rates of death from heart disease.
The most serious scientific challenge to the dietary cholesterol-heart disease link occurred this spring, when the Journal of the American Medical Association published a study that showed no increases in heart disease among healthy people who ate as many as seven eggs per week. The study, conducted by researchers at Harvard School of Public Health and sponsored by the National Institutes of Health (NIH), looked at results from more than 100,000 participants in the Nurse's Health Study and the Health Professional's Follow-Up Study.
"Eggs have perhaps been unfairly targeted as something to avoid," said Meir Stampfer, a lead researcher on the study and a member of a federal advisory committee that, like the AHA, is also updating dietary guidelines.
"You might say, so what?" he continued. "I think the answer is that it's too bad for people to avoid a food that is nutritious and tasty. But also, people thought that by severely restricting eggs in their diet, they were doing what was necessary to minimize the risk of heart disease. They weren't."
Also influential in the reevaluation of the egg has been a meta-analysis of research on how dietary cholesterol does, or does not, affect cholesterol levels in the blood. The analysis of 224 dietary fat and cholesterol studies by Wanda Howell of the University of Arizona found that dietary cholesterol had half the impact on blood cholesterol levels that the National Institutes of Health had determined in 1988. Howell's research was published in 1997 in the American Journal of Clinical Nutrition, and was sponsored by the American Egg Board, which represents egg producers. Similar findings from a British team were published in the British Journal of Nutrition around the same time.
Meanwhile, substantial research is also underway to create a more healthful egg. These eggs come from hens that are fed organic or otherwise special diets so they will produce eggs lower in cholesterol and higher in other nutrients. Studies of the fat content of these "designer eggs" have shown, for instance, that changing the feed that hens consume can modify the cholesterol content and enhance the nutritional value of their eggs.
The niche market for these "nutritionally enhanced" eggs remains small--3 to 5 percent of the total, egg industry officials say--but it could expand significantly as the science progresses. While it does not appear possible to create an egg without considerable cholesterol content, researchers say it is certainly possible to produce eggs that are overall better for the heart than today's generic eggs.
Companies such as Eggland's Best, Country Hen and Gold Circle Farm now use all-vegetarian feeds high in canola oil or sea algae and kelps that are high in vitamin E and in Omega-3 fatty acids, which have been associated with decreasing the risk of heart disease. These nutrients appear in the eggs of chickens fed this special diet.
The U.S. Department of Agriculture has approved a label for Eggland's Best eggs that claims they have 25 percent less saturated fats than generic eggs and about 12 percent less cholesterol. They also claim three times as much Omega-3 fatty acids as generic eggs and seven times more vitamin E. Other designer eggs claim considerably more Omega-3s.
"When we went public with eggs for cholesterol-conscious consumers [in the mid-1990s], some people had a hard time with us because we were encouraging people to revisit eggs," said Manette Richardson, a dietitian for Eggland's Best. "That's why we did the clinical research, to show that we were producing a nutritionally enhanced egg. We went through all the barriers, and think we helped people look at all eggs differently while we were doing it."
The president of Eggland's Best, Charles Lanktree, said that his company, based outside Philadelphia, is the largest in the specialty egg market, and that he now sells 300 million premium eggs annually--up from 100 million in 1995. "We believe that we are bringing people back to eating eggs that have either eliminated them from their diets, or who have seriously cut back on eggs for presumed health reasons," Lanktree said.
Artemis Simopoulos, the former chief of the Nutrition Coordinating Committee of the NIH and now president of the nonprofit, educational Center for Genetics, Nutrition and Health in Washington, believes that properly produced eggs can serve an important nutritional role as sources for Omega-3 fatty acids--healthful fats that some researchers believe are seriously deficient in the American diet.
Simopoulos, who pioneered research into the benefits of eggs rich in Omega-3 fatty acids more than a decade ago, said that researchers have found that eggs laid by hens on high Omega-3 diets did not increase the cholesterol levels of people who ate them. She said that getting the proper balance of fatty acids in the body reduces the liver's need to produce more cholesterol on its own.
Much of this information, she added, has been known for some time, but spreading the message that eggs can be nutritious and safe in terms of cholesterol has been difficult.
"Many groups and individuals in the field have long-standing positions regarding eggs and cholesterol, and it will be very hard for them to change," she said. "It will take more than scientific data to modify guidelines and recommendations."
While there are few dissenters today regarding the positive attributes of Omega-3 fatty acids, there are those who say eggs are not necessarily the best way to deliver them. In order to consume useful concentrations of the fatty acids, these critics say, a person would have to eat quite a few eggs.
There are also researchers and experts who remain convinced that cholesterol from eggs is a significant problem.
"There are certainly very good people who think that cholesterol from the diet remains very important," said Nancy Ernst, nutrition coordinator for the National Cholesterol Education Program at NIH, and federal liaison to the AHA nutrition committee. "The committee wants to look at the collective evidence on cholesterol--and eggs are a major source of cholesterol--and they don't want to be unduly persuaded by one study or another."
Complicating the fate of the egg further is another nutrition advisory committee, which is now meeting to update the federal government's national dietary guidelines. This group, working under the aegis of the U.S. Department of Agriculture, is expected to announce its new recommendations by year's end. Members of the AHA nutrition committee say they will look to the new national dietary recommendations for guidance before issuing their new position on eggs.
The federal guidelines have never specifically advised people to limit their consumption of eggs, although they do recommend that Americans consume no more than 300 mg of cholesterol per day. That recommendation is used to calculate the percentages found on product nutrition labels mandated by the Food and Drug Administration.
Members of the AHA nutrition committee say it would be difficult to change the 300 mg per day recommendation on cholesterol. But there may still be ways to modify the guidelines so that people could be more flexible about eating eggs.
Ronald Krauss, a senior scientist at the Lawrence Berkeley National Laboratory at the University of California and a member of the AHA nutrition committee, said that people who already eat a good diet low in animal fats and high in fruits, vegetables and fiber may be able to safely eat more than three or four eggs per week.
"The impact of dietary cholesterol is very difficult to detect in people eating a rounded diet," he said. "If that kind of overall diet approach is included in our discussions, then it might be possible to give a broader cholesterol intake for people who already limit their saturated fats."
In addition, he said, the committee is looking into ways to distinguish between the cholesterol in foods such as eggs and shellfish from the cholesterol in red meats and cheese, which are also high in saturated fats.
"Perhaps we can factor out foods like eggs and shellfish from the overall cholesterol recommendation, and create a recommendation that reflects the research into the less problematic nature of their cholesterol," he said.
Nonetheless, researchers and nutrition experts generally agree that placing some limits on dietary cholesterol should remain a goal for Americans--although not quite as rigid a goal as before.
"Nutrition is a notoriously difficult area of science," said AHA nutrition committee chair Eckels. "Our information cannot be as precise as with a drug experiment, and we have to weigh so many factors. But one thing that's clear is that we need to get away from the idea there are good foods and bad foods."
CAPTION: The Egg Bounces Back (This graphic was not available)