By: Andrea Platzman, R.D.
For many years, eggs have gotten a bad rap as a forbidden food because of their high cholesterol content. The mere mention of cholesterol was enough to banish eggs from the diets of many Americans and the phrase "no cholesterol" became a positive selling point in many advertising campaigns. Despite those messages, the American Egg Board, Park Ridge, IL, estimates that this year the average American will consume 256 eggs, an increase of approximately 9% over 1991s 233.5 eggs.
Each nutrient-dense egg packs 6 grams of protein, 318 IU vitamin A, 4.5 grams of fat (mostly polyunsaturated and monounsaturated fats, with only 1.5 grams saturated fat) and 75 calories. Eggs are also significant sources of vitamins E, D and B12, folate, riboflavin and iron. In fact, egg yolks are one of the few foods that naturally contain vitamin D. Egg whites are considered an ideal protein because they contain all of the essential amino acids in proper proportion.
"Blood cholesterol is packaged along with triglycerides in low density units," explains Jack Avens, Ph.D., professor, department of food science and human nutrition at Colorado State University, Fort Collins, CO. "Most blood cholesterol is manufactured in the liver, with a relatively small amount coming from the diet, regardless of the amount of cholesterol in the diet. Increasing dietary fat will cause the liver to increase the production of LDL units to carry the triglycerides and cholesterol in the blood, and this increases the level of cholesterol in the blood."
In a recent meta-analysis, Wanda Howell et al. the University of Arizona, Tucson reviewed more than 30 years of research on the effects of dietary fat and cholesterol on plasma cholesterol levels. This analysis looked at more than 8,000 subjects in 224 trials and found that saturated fat was a major contributor to a rise in blood cholesterol. Every 50-mg change in dietary cholesterol, equated to a 1mg/dl change in plasma cholesterol. By comparison, a 5% reduction in saturated fat calories would result in a 10mg/dl decrease of plasma cholesterol levels.
"Although the American Health Association recommends an average daily intake of no more than 300 mg of cholesterol, some experts believe that two-thirds of Americans can handle a cholesterol intake of 300 to 400 mg without significantly raising blood cholesterol," says Kenneth Hall, Ph.D., professor, department of nutritional sciences at University of Connecticut, Storrs, CT.
Liquid and precooked eggs
Liquid eggs are whole eggs removed from shells, mixed and pasteurized prior to packaging and freezing. Egg substitutes may contain egg whites (albumin) plus added vitamins, minerals, artificial color and other additives. "Not containing yolk, egg substitutes do not contain cholesterol; however, I believe nutritionally and functionally, they are inferior to whole eggs," says Avens. Hall disagrees: "Egg substitutes are ideal for those individuals who are encouraged by their doctors to reduce egg consumption."
"Pre-cooked eggs are a growing category in the foodservice industry because they effectively address food safety concerns and provide portion control, reduced labor cost and improved convenience and consistency," explains Jay Schuman, Ph.D., director of food safety, Michael Foods Egg Products Company, Minneapolis.
According to the U.S. Centers for Disease Control and Prevention, the rate of Salmonella enteritidis in raw or undercooked eggs has dropped by more than one-third between 1996 and 1998. Only a very small number of eggs might contain S. enteritidis. "About one out of every 20,000 eggs produced might contain the bacteria, which statistically means that if I consume one raw egg or undercooked egg every day, I should on the average get samonellosis once every 54.7 years," notes Hall.
Symptoms of the disease salmonellosis include abdominal cramps, fever, headache, nausea, vomiting and diarrhea. According to the American Egg Board, S. enteritidis will not survive if held at 140°F for 3.5 minutes or if they reach an end-point temperature of 160°F.
Most outbreaks have been in foodservice, where pre-cooked eggs can make a difference in decreasing the rate of S. enteritidis. In fact, one way to eliminate this problem is to use powdered eggs. "Traditionally, egg has been used for its functionality as a food ingredient; however, functional dairy powders can be manufactured with the same functionality as egg, but without the risk of contamination or the inconvenience of an eggs short shelf life," explains Brad McKay, director of marketing and business development, Ingredients and Export Division, Parmalat, Etobicoke, Ontario, Canada. Eggless products can also be used for the allergenic population.
"We can expect to see a continued interest in ways to optimize the vitamin and lipids composition of eggs by modifying the diet of egg-laying hens to produce, for example, omega-3 fatty acid eggs," says Schuman. Over the last 100 to 150 years, our diet has changed, losing most of the omega-3 fat and increasing the amount of omega-6 fat. This might have serious health consequences. (See Nutrition Notes, "Balancing Fatty Acids," April 2000.)
Eggs with extra omega-3 fatty acids are currently produced by several food companies. OmegaTech, based in Boulder, Colorado, uses the fishs source of DHA a tiny single-cell marine algae called Schizochytrium incorporated into the live-stock feed. Docosahexaenoic acid (DHA) is an essential long-chain omega-3 polyunsaturated fatty acid. DHA is critical for the development and function of the brain and eyes and helps to manage communication among brain cells.
"Each egg contains 225 mg of omega-3 fatty acids (150 mg from algae and 75 mg from flaxseed also put into the live-stock feed). Four OmegaTech eggs equals the amount of omega-3 fatty acids found in one serving of salmon," says Mary Elizabeth Van Elswyk, Ph.D., R.D., director of scientific affairs, OmegaTech.
DHA also helps keep the heart and blood vessels running smoothly by regulating the fat profile (low-density lipoprotein, high-density lipoprotein and triglycerides), supporting a normal heart beat and keeping blood vessels flexible.
"Since egg-laying hens have the ability to produce and deposit antibodies into the egg yolk, research and development efforts are also underway to explore the use of antibody-enriched eggs to prevent specific types of infection in humans and food production animals," says Schuman. n
Andrea D. Platzman,
a registered dietitian who is a consultant to the food industry, regularly
writes for nutrition publications. She earned a masters degree in nutrition
from New York University, and has a strong culinary and business background.
Andrea D. Platzman, a registered dietitian, writes regularly for nutrition publications. She earned a master's degree in nutrition from New York University, and has a culinary and business background.
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