What is the most abundant element in the human body?

Answer by  dsmith42 (371)

The most abundant substance in the human body is water (nearly 70%). Water is about 90% oxygen, by mass. Therefore, your body is about 60%, by mass, oxygen just from all the water in it.

Answer by  phoenix27 (75)

The human body is made up primarily of water, containing hydrogen and oxygen, and organic compounds composed of carbon and oxygen. This means that oxygen makes up the bulk of the mass of a human body, roughly 65%. Carbon is the second most abundent, making up 18% of body mass.