Asparagus actually contains chemicals that pass through the body and attract fish through our urine. The asparagus has been used for centuries as food. The ancient Greeks, Romans, and Egyptians all used the plant.
They dried the stems to use in the winter and cooked them and ate them raw in the summer. Asparagus has few calories, is full of antioxidants, and contains vitamins A, B6, C, E, and K. Its high levels of potassium actually helps slow down calcium loss in the body and is thought to aid in heart disease.
U.S. pilots were given asparagus in their ration kits in the Pacific Ocean region. They were working for the US spy organization called the Office of Strategic Services. It is really quite clever. Asparagus contains mercaptan, which is a highly attractive chemical.
The idea was that should the pilots be shot down, they could eat the asparagus and the mercaptan chemical would pass through their urine. The pilot could pee in the water and the mercaptan in their urine would attract fish to the area and they could catch them easier and have food to eat.