The 4 Main Building Blocks of the Human Body

If we are our bodies, what are our bodies made of?

99% of the total number of atoms in the human body are either Hydrogen (H), Carbon (C), Nitrogen (N) or Oxygen (O). Ratios are approximately:

• 63% Hydrogen
• 24% Oxygen
• 9% Carbon
• 3% Nitrogen

Seven elements make up 0.9% of the remaining atoms. They are: Sodium (Na), Magnesium (Mg), Phosphorus (P), Sulfur (S), Chlorine (Cl), Potassium (K) and Calcium (Ca).

The last 0.1% is divided between eleven elements that are needed in trace amounts, all of them metals or metaloids except for Fluorine (F), Selenium (Se) and Iodine (I). There’s also three more that we aren’t sure yet if they are required for life or not: Boron (B), Silicon (Si) and Nickel (Ni). For their atomic masses, see the periodic table of the elements above.

I find it fascinating that our extreme complexity can be reduced to 4 main building blocks. Very light elements, too.

Source: Alberts, Molecular Biology of the Cell, 5th Edition. P. 47, 49.

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