|
Health Options
Alan Titchenal |
Cracks found in
latest egg studyThe incredible edible egg has come under attack again. But before you toss eggs from your diet, you need to understand the many problems with an egg study conducted in Japan.
The conclusion of the study -- published in this month's American Journal of Clinical Nutrition -- indicates that eggs are bad for health, especially for women. But in our opinion, limitations in the design of the study lead to problems with its conclusion. The results clash with more than 50 studies reporting that eggs and dietary cholesterol are not the villains they have been made out to be. Even another Japanese study published in 1975 showed that egg cholesterol had little effect on blood cholesterol compared with butter or lard.
Question: How was the latest Japanese study conducted?
Answer: In 1980 about 5,000 women and 4,000 men over age 30 completed a single food questionnaire that asked how frequently they ate various types of foods. Participants were then divided into five groups according to how many eggs they ate. Fourteen years later, researchers recorded how many participants in each group had died and further subdivided them according to cause of death -- stroke, heart disease or cancer.
Q: What are the problems?
A: Only a single food questionnaire was completed, which assumes that the participants' eating habits didn't change in 14 years. Also, fewer than 15 percent of the participants died during the study, so the fate of most is yet to be known.
Although the study reported that women who ate the most eggs had the greatest risk of death, only 69 of the 5,000 women were in the high-egg group -- those eating more than two eggs a day in 1980. Only 13 of these women died during the 14 years, and only one died of heart disease. Also, women in the group that ate the least eggs had about the same incidence of heart disease as those who ate the most.
In men, egg consumption was not related to death, and none of the men in the group eating the most eggs died from heart disease. Interestingly, men eating one egg a day or more had a lower risk of death from heart disease than those eating fewer eggs. But you won't hear this in the headlines.
Q: Are there good reasons to include eggs in a healthy diet?
A: Like most foods, eggs are not all good or all bad. On the positive side, they are a good source of high-quality protein along with several vitamins and minerals. Also, much of the yellow in egg yolks is from lutein and zeaxanthin, compounds that are important for the retina and might help to prevent age-related macular degeneration, a major cause of lost vision in the elderly.
For most of us, the American Heart Association recommends eating less than 300 milligrams of cholesterol per day. People with high blood cholesterol should eat no more than 200 milligrams per day -- the amount in one egg.
Basing your dietary decisions on any single study is like putting all of your eggs in one basket. Not a smart thing to do!
See the Columnists section for some past articles.
Alan Titchenal, Ph.D., C.N.S. and Joannie Dobbs, Ph.D., C.N.S. are nutritionists in the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, UH-Manoa. Dr. Dobbs also works with the University Health Services and prepares the nutritional analyses marked with an asterisk in this section.