How do they decide that one particular food increased growth? My kids didn't lack for protein, but my son was so short until he hit puberty that well-meaning friends suggested he should be given growth hormones.

I have no problem with eggs being promoted as a good source of protein - I love them & eat them every single day - but I eat a lot of other things, too. Perhaps if the children in the study were malnourished, then one egg a day would be better. But how about one hamburger patty or other serving of meat?