This vegetable has a long history, having been cultivated for over 2000 years, starting with the Roman's and Greeks who recognised its nutritional and medicinal uses. Asparagus root is used by herbalists to treat urinary tract infections, and asparagus itself has diuretic properties.
There are three main types of asparagus; green, white and purple. White asparagus is grown with ultra violet light and when buying look for completely white examples, just as green should be completely green. Purple asparagus was developed in Italy and has a higher sugar and lower fibre content than regular Asparagus officinalis. Bodybuilders have long used asparagus pre-contest for its noted diuretic effect; however, asparagus is one of the most nutritionally dense vegetables available. An individual asparagus spear is on average less than 4 calories per spear, with an 100g serving providing around 20 calories with less than 5mg of sodium, 3g of carbohydrate, 3g of protein, and no fat whatsoever. You will also get a healthy 3g of fibre.
Asparagus is packed with Vitamin K, whose role is for blood clotting and bone metabolism. Next up is folate; 100g will give you over half of your daily recommended intake (over 200mcg). Folate deficiency leads to anaemia, but we also need folate for the proper metabolism of homocysteine, and importantly for the production of RNA and DNA when making new cells. The proper action of DNA and RNA helps prevent cancer while high levels of homocysteine are found in up to 40% of people with heart disease, and elevated levels of homocysteine interfere with the formation of collagen, weakening the integrity of blood vessels, and all connective tissue. Finally folate helps prevent against neural tube defects in babies; which is why pregnant women are encouraged to take their folic acid supplement.
In addition to folate and vitamin K, asparagus also provides vitamin A, vitamin E, vitamin 6, vitamin B6, thiamin riboflavin, potassium, magnesium, selenium, manganese, tryptophan and copper. If this wasn't enough to convince you that asparagus should regularly feature in your '5 a day' then consider that it is also a natural source of rutin, which helps strengthen capillary walls, and of glutathione which is a powerful anti-carcinogen and anti-oxidant.
Finally yes asparagus, because it contains sulphur compounds (e.g. thiols and thiol esters), can make your pee smell, although only around 40% of the population have the genes to smell it!