Asparagus has always been popular, but it did go out of favor for a while during the Middle Ages and was popular again during the 1600s. It was known to many ancient peoples including Romans, Egyptians and Greeks who cooked and ate it during the summer months and dried the stems to keep them for use during the winter.
Asparagus has very few calories and contains anti-oxidants, but is also full of vitamins A, B6, C, E and K. There is some evidence that it may be beneficial to those with heart disease and that the high levels of potassium in asparagus actually slow down the loss of calcium from the body. Asparagus was included as part of the emergency ration kit given to American pilots.
The idea of the pilots eating asparagus was that it was a very valuable way of feeding themselves. Asparagus contains mercaptans which are powerful chemical attractants, and when the vegetable is eaten, these chemicals pass into the urine.
The pilots were told to urinate into the water, so that the chemicals would spread through the water and attract fish to the area, making them much easier to catch. This was of course, a valuable food source and the smell of asparagus is present in the urine after just fifteen minutes in many people, or thirty minutes at most.