Table 4
Macroelements and their roles in the human body (Whitney and Rolfes2010)
Macroelements	Roles
O, C, H, N	In water and the molecular structures of proteins
Ca	Structure of bone and teeth; muscle and nerve activity
P	Structure of bone and teeth; intermediate in REDOX metabolism and production of ATP in energy
Mg	Important in bone structure, muscle contraction, and metabolic processes
Na	Major electrolyte of blood and extracellular fluid; required for the maintenance of pH and osmotic balance; nerve and muscle signaling
K	Major electrolyte of blood and intracellular fluid; required for the maintenance of pH and osmotic balance; nerve and muscle signaling
Cl	Major electrolyte of blood and extracellular and intracellular fluid; required for the maintenance of pH and osmotic balance; nerve and muscle signaling
S	Element of the essential amino acids methionine and cysteine; contained in the vitamins thiamine and biotin. As part of glutathione, it is required for detoxification. Poor growth due to reduced protein synthesis and lower glutathione levels potentially increasing oxidative or xenobiotic damage are consequences of low sulfur and methionine and/or cysteine intake.

Chen et al. Progress in Biomaterials 2012 1:2   doi:10.1186/2194-0517-1-2