| Table 1 |
| The Most Common Elements on Earth and Their Distribution in the Human Body |
|
Element
|
Symbol
|
Atomic Number
|
% of Human Body by Weight
|
Approximate % of Earth's Crust by Weight
|
Importance of Function
|
| Oxygen |
O
|
8
|
65.0
|
46.6
|
Necessary for cellular respiration, component of water |
| Carbon |
C
|
6
|
18.5
|
0.03
|
Backbone of organic molecules |
| Hydrogen |
H
|
1
|
9.5
|
0.14
|
Electron carrier, component of water and most organic molecules |
| Nitrogen |
N
|
7
|
3.3
|
Trace
|
Component of all proteins and nucleic acids |
| Calcium |
Ca
|
20
|
1.5
|
3.6
|
Component of bones and teeth, trigger for muscle contraction |
| Phosphorus |
P
|
15
|
1.0
|
0.07
|
Backbone of nucleic acids, important in engergy transfer |
| Potassium |
K
|
19
|
0.4
|
2.6
|
Principal positive ion in cells, important nerve function |
| Sulfur |
S
|
16
|
0.3
|
0.03
|
Component of most proteins |
| Chlorine |
Cl
|
17
|
0.2
|
0.01
|
Principal negative ion bathing cells |
| Sodium |
Na
|
11
|
0.2
|
2.8
|
Principal positive ion bathing cells, important in nerve function |
| Magnesium |
Mg
|
12
|
0.1
|
2.1
|
Critical component of many energy-transferring enzymes |
| Iron |
Fe
|
26
|
Trace
|
5.0
|
Criticial component of hemoglobin in the blood |
| Copper |
Cu
|
29
|
Trace
|
0.01
|
Key component of many enzymes |
| Zinc |
Zn
|
30
|
Trace
|
Trace
|
Key component of some enzymes |
| Molybdenum |
Mo
|
42
|
Trace
|
Trace
|
Key component of many enzymes |
| Iodine |
I
|
53
|
Trace
|
Trace
|
Component of thyroid hormone |
| Silicon |
Si
|
14
|
Trace
|
27.7
|
N/A |
| Aluminum |
Al
|
13
|
Trace
|
6.5
|
N/A |
| Manganese |
Mn
|
25
|
Trace
|
0.1
|
N/A |
| Fluorine |
F
|
9
|
Trace
|
0.07
|
N/A |
| Vanadium |
V
|
23
|
Trace
|
0.01
|
N/A |
| Chromium |
Cr
|
24
|
Trace
|
0.01
|
N/A |
| Boron |
B
|
5
|
Trace
|
Trace
|
N/A |
| Cobalt |
Co
|
27
|
Trace
|
Trace
|
N/A |
| Selenium |
Se
|
34
|
Trace
|
Trace
|
N/A |
| Tin |
Sn
|
50
|
Trace
|
Trace
|
N/A |
