Incubation and Embryology - University of Illinois

Eggs and Cholesterol

One of the greatest challenges to egg producers today is the adverse publicity concerning the cholesterol content of eggs. A recent newspaper advertisement for an egg substitute carried the following statement: "Nature doesn't goof very often, but when she does, look out. Take nature's egg. It's packed with good things you should eat, except for one, cholesterol."

Cholesterol in perspective

Since cholesterol is a key component in the diet-heart controversy, let's take a closer look at this substance. What is it? Where does it come from? What does it do in the body?

Cholesterol is a complex fatty substance found in every living cell. We cannot live without it. It provides the building blocks from which the body makes its own supply of sex and adrenal hormones. Cholesterol can also be converted to vitamin D in our body and used for the calcification of bones and teeth.

Our body is capable of making its own supply of cholesterol. In fact, most of the cholesterol found in our body is made there; only part of it comes from the food we eat. The liver and intestines are the primary sites where it is manufactured. Overproduction of cholesterol may be the most important factor contributing to arteriosclerosis, a form of hardening of the arteries. Probably 90 percent of all cases of strokes and heart attacks are due to arteriosclerosis.

Some research findings

Numerous dietary studies have been undertaken to determine the effect of cholesterol intake on the level in the body.

Thirteen patients at the Highland Hospital in Oakland, California were fed the equivalent in egg yolks of that found in 15 eggs per day for a 3 week period. The serum cholesterol did not increase significantly in any except two bedridden, obese patients. Four of the 7 ambulatory patients in the study actually showed a slight decrease in serum cholesterol.

In the Ireland-Boston Heart Study the researchers followed 600 Irishmen between the ages of 30 and 60 who had lived in Boston for 10 or more years and their brothers who had never left the old country. The Irish brothers ate about twice as many eggs as their American brothers--averaging over 14 per week. Yet, the Irish brothers had lower levels of cholesterol in their bloodstream, and their hearts were rated from 2 to 6 times healthier. The same Harvard doctor examined both groups. More physical exercise was given as a possible reason for this difference.

Dr. Robert Itchiness, a cardiologist in New York city specializing in metabolic disorders, has treated over 8,000 patients. He lowered the serum cholesterol markedly in 63 percent of his patients with a diet high in meat, milk, and eggs. Dr. Itchiness believes that 95 percent of all heart trouble is associated with high serum triglycerides and attributes this to the staggering increase in sugar consumption--up from 7 pounds per person in 1840 to over 100 pounds today.

Probably the most comprehensive research project in the diet-heart field was the Framingham Heart Program which began in 1948 in a community 30 miles west of Boston. Five thousand people were involved over a period of 20 years. Their diets were not changed, but what each person ate was recorded. Four risk factors associated with coronary heart disease were identified:

The report issued after the Framingham Study was concluded said: "There is no suggestion of any relationship between diet and the subsequent development of coronary heart disease in the study group despite a distinct elevation of serum cholesterol in those developing coronary heart disease."

Changes in diet

Some rather striking changes have occurred in the average American's diet during the past 15 years. Consumption of vegetable oils has increased markedly while consumption of animal fats has declined. Per capita consumption of eggs, butter, and fat meats has declined. In spite of these shifts, cardiovascular disease has increased. This suggests other risk factors are playing an increasingly important role. Nevertheless, many in the medical profession still recommend major dietary changes for the entire population.

In conclusion

Little doubt exists that high blood serum cholesterol levels are related to higher incidence of heart disease. But there is considerable variation in individual's ability to handle cholesterol. Most people appear to be able to regulate the production of cholesterol in their body according to dietary changes; others cannot. For those who cannot, special precautions need to be taken. But a radical dietary change for the entire population does not seem to be desirable nor warranted.

Source: H.S. Johnson and S.F. Ridlen

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