Back to Full Table

Elements essential to the human body
[Extracts from "Introduction to the Chemistry of Life" by Berlow, Burton and Routh, Saunders College Publishing, New York, 1974.]

Hydrogen No 1 Group 1
Most obviously as part of the water molecule, H2O, hydrogen is also part of many other essential simple molecules and complex organic molecules including DNA.

Carbon No 6 Group 4
Carbon dioxide, CO2, is produced by animals and taken in by plants. The plants then use the CO2, with water, H2O, and with the help of sunlight and nutrients from the soil, to make the gigantic number of organic compounds we find in the plant world. Carbon is the fundamental atom in organic molecules including DNA.

Nitrogen No 7 Group 5
One of the most important elements for life. The simplest molecule NH3, ammonia, is important in our internal chemistry. Often found as part of organic molecules is the NH2 group, typical of an amine and found in amino acids and proteins and in DNA..

Oxygen No 8 Group 6
In its role as the central atom in water, H2O, oxygen provides most of your body weight. Oxygen-containing ions such as nitrates (NO3), carbonates (CO3) and phosphates (PO4) combine with ions such as Ca2 and Al3. We breathe oxygen molecules (O2) from the air and transport these molecules in the blood to cells of the body. Oxygen is one of the five elements in DNA.
H2S, with sulphur from the same oxygen group 6, is the 'rotten egg' poisonous gas. H2Te, with tellurium from the same group 6, is the worst smelling inorganic compound known.

Fluorine No 9 Group 7
Too much fluorine can be as injurious as too little. If the fluoride ion (F-) level in water is about 1 part per million, tooth decay in children is cut in half compared with water deficient in fluoride.

Sodium No 11 Group 1
All animals and plants contain large amounts of sodium and potassium cations dissolved in water. Both ions are often accompanied by the chloride ion, since there must be an equal number of positive and negative charges in any small region. The sodium ion is mostly found in the fluids surrounding the cell. A large number of body processes depend not only on the presence of Na and K ions, but on the proper balance being maintained between them.

Magnesium No 12 Group 2
Magnesium ions are essential to the body, especially for nerve impulses and muscle contraction. There are many enzymes that include magnesium as part of their structure.

Silicon No 14 Group 4
Silicon has been shown to be an essential element in the chick and rat, and thus may have a role for humans.

Phosphorus No 15 Group 5
Very important in life. Phosphates are involved in DNA and in energy transfer processes.

Sulphur No 16 Group 6
Is found in protein molecules, forming part of the 'bridge' structure which holds protein molecules together. H2O is essential water but H2S, from the same group 6, is the 'rotten egg' poisonous gas.

Chlorine No 17 Group 7
The chloride ion (Cl-) is the major anion of the human body, forming salts. Stomach acid is a solution of hydrochloric acid HCl. Chlorine is used to kill bacteria in drinking water.

Potassium No 19 Group 1
All animals and plants contain large amounts of sodium and potassium cations dissolved in water. Both ions are often accompanied by the chloride ion, since there must be an equal number of positive and negative charges in any small region. The potassium ion is generally found inside the cell. A large number of body processes depend not only on the presence of Na and K ions, but on the proper balance being maintained between them.

Calcium No 20 Group 2
Calcium ions make up about 2% of our body weight, almost entirely in the bones and teeth. A proper level of calcium in the body is needed for nerve response, muscle contraction (include heart pumping) and even the maintenance of correct body temperature. Ca ions must also be present for the clotting of blood.

Vanadium No 23 1st Transition Series
Required by some animals other than humans and there is no clear evidence of how it may work in the human body.

Chromium No 24 1st Transition Series
Known since 1959 to serve a variety of roles in the human body.

Manganese No 25 1st Transition Series
Has many essential functions in every cell. A manganese deficiency is almost impossible to have, and thus we are not absolutely sure what symptoms would result.

Iron No 26 1st Transition Series
Perhaps the most essential transition metal in the body where an iron-containing molecule called haemoglobin carries oxygen from the lungs to the rest of the body. Small amounts of iron are found in every tissue cell in molecules that use oxygen. About 3% of the iron in the body is in muscle cells in a molecule called myoglobin. Both ferrous (Fe2+) and ferric (Fe3+) ions are involved in energy-producing processes.

Cobalt No 27 1st Transition Series
Cobalt is an essential part of one molecule, vitamin B12. Like iron in haemoglobin, cobalt serves to hold the large vitamin molecule together and to make it function properly.

Nickel No 28 1st Transition Series
Required by some animals other than humans and there is no clear evidence of how it may work in the human body.

Copper No 29 1st Transition Series
Required for a variety of roles in the body, several of which are connected to the use of iron. Deficiency of copper will result in weak blood vessels and bones as well as nerve damage.

Zinc No 30 1st Transition Series
Zinc is essential for normal growth of genital organs, wound healing, and general growth of all tissues. It is also associated with the hormone insulin, which is used to treat diabetes. Oysters are an unusually rich source of zinc.

Selenium No 34 Group 6
As important a nutrient as zinc, iron and copper. However too much selenium is harmful - more toxic than mercury or lead.

Molybdenum No 42 2nd Transition Series
Molybdenum is part of several important enzymes. It is not certain if a deficiency is possible or what symptoms would result.

Tin No 50 Group 4
Tin seems to be required by rats and thus possibly by humans.

Iodine No 53 Group 7
Like chlorine, but unlike bromine, iodine is essential to life. It is part of the thyroxine molecule, a thyroid gland hormone that controls growth. Seafood contains enough iodide to supply the body's needs.

[Extracts from "Introduction to the Chemistry of Life" by Berlow, Burton and Routh, Saunders College Publishing, New York, 1974.]


Back to Full Table