Minerals: Understanding the basics

Minerals

Unlike other nutrients, minerals are in their simplest chemical form. Minerals are elements. Whether found in bone, shells, cast iron pots or the soil, they are they same as the minerals in our food and our bodies. The mineral content of plant foods varies with the soil content and the maturation of the plant.

Minerals are categorized as major (macro), or trace (micro). Macro minerals are needed in quantities of 100mg/day or more, while micro minerals are required in much smaller, or “trace,” amounts.

The major minerals are: calcium, phosphorus, potassium, sodium, chloride, magnesium, and sulfur, and the trace minerals are: iron, iodine, zinc, chromium, selenium, fluoride, molybdenum, copper, and manganese.

These 16 essential minerals can be found in the body dissolved in body fluids as ions and/or are part of important compounds, such as calcium and phosphorus in hydroxyapatite found in bones and teeth.

Other minerals, such as lead, are contaminant minerals and not nutrients because they can cause harm by disrupting normal bodily functions and processes, i.e. lead poisoning.

Major 

Element (symbol)

Functions

Main food sources

calcium (Ca)

major structural component of bones and teeth; necessary for many enzymes, including those of blood clotting, muscle contraction and conduction of nerve impulses

milk, cheese, bread and flour (if fortified), cereals, green vegetables

chlorine (Cl)

major negative ion (as chloride,C1) in body fluids; present in stomach secretions as hydrochloric acid (HCl)

salt (sodium chloride, NaCl)

magnesium (Mg)

present in bone, inside cells and in body fluids; needed for some enzymes

milk, bread and other cereal products, potatoes and other vegetables

Phosphorus (P)

present in bones and teeth; essential for ATP and DNA and many other molecules

milk, cheese, bread and cereals, meat and meat products, nuts

potassium (K)

main positive ion inside cells; K+ also present in extracellular fluids; essential for conduction of nerve impulses, also for the maintenance of ion concentration gradients across cell membranes

widely distributed in vegetables, meat, milk, fruit and fruit juices

sodium (Na)

major positive ion in extracellular fluids; Na+ also present inside cells; essential for conduction of nerve impulses and active transport of small molecules across cell membranes (e.g. absorption from gut)

salt (sodium chloride, NaCl)

sulfur (S)

present in proteins

protein-rich foods

Trace 

Element (symbol) Functions Main food sources
chromium (Cr) found in all tissues, may be involved in blood glucose regulation liver, cereals, beer, yeast
cobalt (Co) required for formation of red blood cells liver and other meat
copper (Cu) component of many enzymes; necessary for haemoglobin formation green vegetables, fish, liver
fluorine (F) prevents tooth decay tea, seafood
iodine (I) essential constituent of thyroid hormones milk, seafood, iodised salt
iron (Fe) essential component of haemoglobin in red blood cells meat and offal, bread and flour, potatoes and other vegetables
manganese (Mn) essential component of some enzymes cereals, pulses, nuts
molybdenum (Mo) essential component of some enzymes kidney, cereals, vegetables, fruit
selenium (Se) essential component of some enzymes; associated with Vitamin E activity cereals, meat, fish, eggs, Brazil nuts
Zinc (Zn) essential component of many enzymes and other proteins; required for steroid and thyroid hormone activity meat and meat products, milk and cheese, bread flour and cereal products, peanuts

Supplements

Most people should fulfill their RDAs and get all the nutrients they need by eating a varied and balanced diet. In this section we are not talking about minerals absorbed through a healthy diet but rather the supplements that people take, either prescribed for specific ailments, or the general self-medicating that occurs through misinformation. Unlike from foods, the mega-doses found in supplements can be toxic or can affect the absorption of other nutrients, so should be considered carefully before use.

Some general rules of thumb:

  • If you take a large dose of a mineral, it will compete with other minerals or vitamins to reduce their absorption.
    -The mineral most often taken in large amounts is calcium: The dose is usually several hundred of milligrams, compared to doses of just a few milligrams or even microgram amounts (1,000 micrograms = 1 milligram) of most other minerals. So if you take a calcium supplement, take it at a different time of day than other mineral supplements or a multivitamin/multimineral supplement.
    -Doses of magnesium can also be relatively large and should, ideally, be taken apart from other minerals.
    -If you take high doses of zinc long-term, be aware that it can cause copper deficiency, so you may need to supplement with copper as well.
  • Taking certain supplements with food can reduce gastrointestinal side-effects. For example, taking magnesium with food can reduce the occurrence of diarrhea, and taking iron with food can reduce the chance of stomach upset.
  • Be aware that vitamins and minerals can also affect the absorption and effectiveness of medications.
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