Food 4 Life - Minerals

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Minerals

  • Minerals are required by the body for a variety of functions including
    • Formation of bones and teeth.
    • Essential constituents of body fluids and tissues.
    • Components of enzyme systems.
    • Nerve function.
  • Some minerals are needed in larger amounts than others e.g. calcium, sodium and potassium.
  • Other minerals, although equally important, are required in smaller quantities and are called trace minerals e.g. iron and fluoride.
  • Two minerals most often lacking in the diet are calcium and iron

 

CALCIUM

Calcium is the main mineral in bones and teeth. Absorption is enhanced by vitamin D. An adequate calcium intake is vital to health, especially during periods of growth e.g. childhood, adolescence, pregnancy, and also during lactation. Calcium is sometimes bound by phytates (found in wholegrain cereals and pulses) and oxalates (found in spinach and rhubarb) in foods. This makes it less available to the body. Calcium is easy to absorb from milk and dairy products, but more difficult to absorb from plant foods.


Dietary sources of calcium

Milk, cheese, yoghurt and canned fish containing soft bones e.g. canned salmon, green leafy vegetables, fortified bread.

 

 

IRON

Required for the formation of haemoglobin in red blood cells which transport oxygen around the body. Iron from animal sources (haem iron) is much more easily absorbed than iron from plant sources (non-haem iron). Phytate (in cereals and pulses) and tannins (in tea and coffee)  can bind non-haem iron and reduce its absorption by the body. Vitamin C (in fruit and vegetables) aids the absorption of iron. Loss of blood through injury or during menstruation increases iron requirements. Women and teenage girls are particularly prone to iron deficiency anaemia which causes fatigue.  Anaemia adversely affects work capacity, intellectual performance and behaviour.

 

Dietary sources of iron

Red meat and meat products are rich in available iron. Other meats, eggs, fish, bread, vegetables and fortified breakfast cereals also contain some iron.

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  • Sodium is a mineral which regulates body fluid balance and is involved in nerve function. Most raw foods contain very small amounts of sodium chloride (salt), and during processing, preparation, preservation and serving, additional salt is added. Too much salt has been associated with hypertension (high blood pressure). Excess sweating e.g. due to exercise in a hot environment, may result in an increased requirement for salt.  However, most people consume too much salt and should try to reduce intake to 6g/day.  If you know how much sodium is in a food, you can work out roughly the amount of salt it contains by multiplying the sodium by 2.5. So if a portion of food contains 1.2g sodium, then it contains about 3g salt.

Dietary sources of sodium

The main source of salt in the UK diet is from manufactured foods. It may also be added to foods at the table.  Many food manufacturers have now reformulated their products to reduce the salt content.

  • Folate (folic acid): Involved in the formation of red blood cells. Higher intake of folic acid or foods rich in Folate, before conception and during the first 12 weeks of pregnancy reduce the incidence of neural defects in babies e.g. spina bifida. Dietary sources include wholemeal breads, fortified breakfast cereals, vegetables, oranges, milk, dairy foods, nuts and pulses.