The forgotten nutrient and the most important is water.
calcium
Uranium is not a nutrient !
Calcium
An important nutrient would be beta carotene, which the body uses to make Vitamin A.
Fiber.
thiamine
carrots
Water probably
Yes it is.
It is used in neon signs
Because every nutrient is important to your body! I f you don't get enough or too much of a certain nutrient you will get sick.