Eggs could easily be replaced with salt. Consuming too much salt (more than 2g a day) is heavily discouraged by some because it is said to increase the risks of cardiovascular diseases as well as increase blood pressure to a dangerous level, but others repudiate these claims and assert they are untrue, and that salt has positive health benefits above this limit.
Even if we take a group of people, put them in a closed place and strictly control what they eat, it is extremely difficult to say if a certain food has had a particular impact on X or not. There are some many elements which are unrelated to nutrition at play that X could decrease or increase for any reason other than what one ate: stress, tiredness, physical activity, mood...
Now, I reckon the wisest thing to do is to follow what the author concludes with: eat moderately and have a balanced nutrition. I doubt we'll ever get concrete and truthful research on nutrition soon enough. We first need to learn more about the extremely complex system that is the human body.
Even if we take a group of people, put them in a closed place and strictly control what they eat, it is extremely difficult to say if a certain food has had a particular impact on X or not. There are some many elements which are unrelated to nutrition at play that X could decrease or increase for any reason other than what one ate: stress, tiredness, physical activity, mood...
Now, I reckon the wisest thing to do is to follow what the author concludes with: eat moderately and have a balanced nutrition. I doubt we'll ever get concrete and truthful research on nutrition soon enough. We first need to learn more about the extremely complex system that is the human body.