Apart from water and organic materials (macronutrients), food also contains minerals, about 20 of which are indispensable for human health. Here is an overview of these essential substances.
Presentation and role of minerals within the body
The main function of calcium is its well-known role in constructing and renewing the skeleton.
Calcium also takes part in muscle and cardiac contraction, blood clotting, cellular exchanges, membrane permeability, hormone release and transmission of the nerve impulse.
> The calcium content of foods (2012 Ciqual Food Composition Table)
Magnesium is one of the most abundant minerals in the body. Half of the body’s magnesium is found in bone tissue. It is also a regulator of carbohydrate and lipid metabolism in muscle, cardiac and nervous tissues.
> The magnesium content of foods (2012 Ciqual Food Composition Table)
Along with calcium and magnesium, phosphorus forms the mineral mass of the bony skeleton.
It also helps to maintain the acid/base balance and takes part in most of the body’s biochemical reactions, particularly in the form of adenosine triphosphate (ATP), the main form in which energy is stored and transported inside cells.
Finally, it is an essential constituent of various biological compounds (DNA, RNA, cell membrane phospholipids, etc.).
> The phosphorus content of foods (2012 Ciqual Food Composition Table)
Sodium plays a key role in regulating osmotic pressure, the water-electrolyte balance and the body’s fluid mass. It is the major ion of extracellular fluids.
> The sodium content of foods (2012 Ciqual Food Composition Table)
Iron plays a major role in the production and functioning of haemoglobin, a red blood cell protein which carries oxygen in the body from the lungs to each of the cells. Iron is also a constituent of myoglobin, a protein responsible for muscle oxygenation.
> The iron content of foods (2012 Ciqual Food Composition Table)
Zinc is involved in the activity of more than 200 enzymes, particularly those which take part in protecting against free radicals and those involved in protein synthesis (hence its importance in cell renewal, healing and immunity phenomena).
> The zinc content of foods (2012 Ciqual Food Composition Table)
Selenium is an essential constituent of certain antioxidant enzymes through which it helps to combat free radicals. It also has a stimulatory effect on immunity and therefore generally helps in the body’s defence reactions.
> The selenium content of foods (2012 Ciqual Food Composition Table)
Minerals in the body
Minerals are present in the body in widely differing quantities: around 1 kg for calcium and phosphorus, a few grams for iron, zinc and fluoride and less than 1 mg for chromium and cobalt. In all, minerals account for about 4% of body weight but are involved in a wide range of functions: mineralisation, controlling water balance, enzymatic and hormonal systems, and the muscular, nervous and immune systems. For example, thyroid hormones cannot be made without iodine, nor haemoglobin without iron and no muscular contraction can occur without calcium, potassium and magnesium. Except for iodine, fluorine and cobalt, all of the mineral elements play multiple roles.
Daily intake of minerals compensates for loss, and a balanced and varied diet guarantees adequate intake. Mineral elements are water soluble, which is why there is a certain amount of loss depending on how food is prepared.