cube of relative abundance by mass of elements in an average adult human body down to 1 ppm About 99% of the mass of the human body is made up of six elements:
oxygen,
carbon,
hydrogen,
nitrogen,
calcium, and
phosphorus. Only about 0.85% is composed of another five elements:
potassium,
sulfur,
sodium,
chlorine, &
magnesium. All 11 are necessary for life. The remaining elements are
trace elements, of which more than a dozen are thought on the basis of good evidence to be necessary for life. Some elements (silicon, boron, nickel, vanadium) are probably needed by mammals also, but in far smaller doses. Bromine is used by some (though not all) bacteria, fungi,
diatoms, and
seaweeds, and opportunistically in
eosinophils in humans. One study has indicated bromine to be necessary to
collagen IV synthesis in humans.
Fluorine is used by a number of plants to manufacture toxins but in humans its only known function is as a local topical hardening agent in tooth enamel.
Elemental composition list The average
adult human body contains approximately
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. 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. 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 other element. The elements listed below as "Essential in humans" are those listed by the US
Food and Drug Administration as essential nutrients, 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 B12). Elements listed as "Possibly" or "Probably" essential are those cited by the US
National Research Council as beneficial to human health and possibly or probably essential. • Iron = ~3
g in males, ~2.3 g in females Of the 94 naturally occurring chemical elements, 76 are listed in the table above. Of the remaining 18, it is not known how many occur in the human body. Most of the elements needed for life are relatively
common in the Earth's crust.
Aluminium, the third most common element in the
Earth's crust (after
oxygen and
silicon), serves no function in living cells, but is toxic in large amounts, depending on its physical and chemical forms and magnitude, duration, frequency of exposure, and how it was absorbed by the human body.
Transferrins can bind aluminium.
Periodic table ==Composition==