<P> The average 70 kg (150 lb) adult human body contains approximately 7027700000000000000 ♠ 7 × 10 atoms and contains at least detectable traces of 60 chemical elements . About 29 of these elements are thought to play an active positive role in life and health in humans . </P> <P> The relative amounts of each element vary by individual, mainly due to differences in the proportion of fat, muscle and bone in their body . Persons with more fat will have a higher proportion of carbon and a lower proportion of most other elements (the proportion of hydrogen will be about the same). The numbers in the table are averages of different numbers reported by different references . </P> <P> The adult human body averages ~ 53% water . This varies substantially by age, sex, and adiposity . In a large sample of adults of all ages and both sexes, the figure for water fraction by weight was found to be 48 ± 6% for females and 58 ± 8% water for males . Water is ~ 11% hydrogen by mass but ~ 67% hydrogen by atomic percent, and these numbers along with the complementary% numbers for oxygen in water, are the largest contributors to overall mass and atomic composition figures . Because of water content, the human body contains more oxygen by mass than any other element, but more hydrogen by atom - fraction than any element . </P> <P> The elements listed below as "Essential in humans" are those listed by the (US) Food and Drug Administration as essential nutritients, as well as six additional elements: oxygen, carbon, hydrogen, and nitrogen (the fundamental building blocks of life on Earth), sulfur (essential to all cells) and cobalt (a necessary component of vitamin B). Elements listed as "Possibly" or "Probably" essential are those cited by the National Research Council (United States) as beneficial to human health and possibly or probably essential . </P>

Which element is most present in the human body