I could make this a quiz. 'What do swimming, sugar, salt and egg yolks have in common?' But that would be too difficult.
These are all related to false wives tales.
* Until 1960, when the Army published its own findings, it was widely believed (and strictly enforced by my mother) that we could not swim for an hour after eating lunch. The Army found it easy to test this thesis. When I was in the Army we were marching immediately after lunch everyday. There was no connection between eating and getting a cramp from prompt exercise.
* Throughout the entire 60s and 70s, and it is still widely believed, that sugar is the reason for children misbehaving after eating ice cream.
Since this was easily measured by sugar levels in the blood, it should have been rejected early on. Sugar, in any form, including ice cream does not create blood sugar any quicker than cheese or avocado.
* Salt has always been identified as a source of potential harm to the heart. It is correct to say that salt, sodium chloride, does cause humans to retain water and slightly increase blood pressure. But careful studies have shown that salt in reduced concentrations in the diet has no direct benefit for heart attacks, stroke or heart disease. Just another old wives tale.
* I personally avoided egg yolks for 25 years because the nutritionist unions supported the old wives tale that egg yolks raise your cholesterol level. While egg yolks themselves are very high in cholesterol, they do not turn into cholesterol inside a human being. We create our own cholesterol independent of how much egg yolk we eat.
I notice that McDonald's is selling an egg white breakfast sandwich. How long before they get the word that customers aren’t asking for it? How long before customers get 'the word'?