| Chemical makeup of the human body | Elements needed for Life |
| The human body is a combination of elements and compounds. The average adult (a 70 kilogram adult) is composed of: | |
| Element | % |
| Oxygen | 65 |
| Carbon | 18 |
| Hydrogen | 10 |
| Nitrogen | 3 |
| Calcium | 1.5 |
| Phosphorus | 1 |
| Sulfur | 0.25 |
| Potassium | 0.2 |
| Chlorine | 0.15 |
| Sodium | 0.15 |
| Magnesium | 0.05 |
| Iron | 0.006 |
| Fluorine | 0.0037 |
| Zinc | 0.0032 |
| Silicon | 0.002 |
| Zirconium | 0.0006 |
| Rubidium | 0.00046 |
| Strontium | 0.00046 |
| Bromine | 0.00029 |
| Lead | 0.00017 |
| Niobium | 0.00016 |
| Copper | 0.0001 |
| Aluminum | 0.000087 |
| Cadmium | 0.000072 |
| Boron | 0.000069 |
| Barium | 0.000031 |
| Arsenic | 0.000026 |
| Vanadium | 0.000026 |
| Tin | 0.000024 |
| Mercury | 0.000019 |
| Selenium | 0.000019 |
| Manganese | 0.000017 |
| Iodine | 0.000016 |
| Gold | 0.000014 |
| Nickel | 0.000014 |
| Molybdenum | 0.000013 |
| Titanium | 0.000013 |
| Tellurium | 0.000012 |
| Antimony | 0.000011 |
| Lithium | 0.0000031 |
| Chromium | 0.0000024 |
| Cesium | 0.0000021 |
| Cobalt | 0.0000021 |
| Silver | 0.000001 |
| Uranium | 0.00000013 |
| Beryllium | 0.000000005 |
| Radium | 0.00000000000000001 |