"An egg contains a lot of good things. It's a good source of protein and it's cheap," he said. "It's not a good idea to cut them out of the diet entirely. Nothing is all bad or all good."
Zeisel and other experts pointed to a battery of new studies that have shown an array of benefits. For example, pregnant women can improve their children's memory function by eating more choline-rich foods, according to the studies. Eggs are second only to beef liver in choline content.
The American Heart Association has updated its guidelines to do away with its prior recommendation limiting the number of egg yolks to be consumed in a week's time to three or four.
However, the AHA does not advise at-risk individuals to scramble to the omelet bar. Foods rich in saturated fat are still on the list of things to avoid for heart patients.
While eggs contain only 70 calories each, they derive most of their calories from fat and are high in dietary cholesterol. But for most people, the choline advantage could outweigh the cholesterol risk.
Zeisel explained that choline is a required nutrient in the body, especially during gestation when the brain's memory center -- the hippocampus -- is formed. He said laboratory animals given extra choline during the latter part of pregnancy gave birth to offspring with improved memory skills. Spatial memory, he said, would be enhanced for life. "That's the memory used when you go to find your car at the airport."
By putting rats through a maze, scientists at UNC,
The Duke study reported that the "normal" -- non-Alzheimer's-related -- memory loss associated with aging was reduced or eliminated in subjects who received increased doses of choline. The numerous experiments revealed that the severity of cognitive impairment as well as when it sets in can be preset by the levels of choline consumed early on.
Zeisel added that breast milk is also rich in choline, so nursing infants would also enjoy the benefits of improved memory. As food preferences change during pregnancy, he said, the mother's appetite for certain foods should lead her to those that are needed at the various stages of development.
In recent years scientists have discovered that new nerve cells are generated in the brain well into adulthood and old age, a theory previously rejected by the scientific community.
"Stem cells for this [memory-related] area of the brain divide more and die more slowly," he said, with an increase in choline consumption before birth. New studies will aim to harness the mechanism to accelerate memory function at any age.