Minerals

• Iron functions:

  • Formation of haemoglobin in red blood cells
  • Binding of oxygen and transporting around the body
  • Function of the immune system
  • Normal energy metabolism
  • Metabolism of drugs and foreign substances that need to be removed from the body
• Dietary iron is found in two forms:

  • Haem iron (from animal sources)
  • Non-haem iron (from plant sources)
• Non-haem iron can be found in cereals, vegetables, pulses, beans, nuts, and fruit
• Absorption of non-haem iron is affected by phytates, fibre, tannins, and calcium, which bind non-haem iron in the intestine, reducing absorption
• Iron deficiency can lead to iron deficiency anaemia, with teenage girls and women of childbearing age needing more iron than males of the same age
• Too much iron, known as haemochromatosis, can cause liver damage
• Sources of iron include offal (liver, kidneys), red meat, egg yolk, green vegetables, whole cereals
• Zinc is involved in numerous aspects of cellular metabolism and necessary for enzymes
• Sources of zinc include meat, fish, whole grains
• Iodine is essential for the correct functioning of the thyroid gland, controlling metabolism in the body
• Iodine deficiency can lead to goitre (enlargement of the thyroid gland causing swelling of the neck) and lack of energy, obesity
• Sources of iodine include fish, vegetables grown near the sea, and some countries use iodized salt
• Water is essential for body fluids, regulating temperature, and eliminating waste materials
• The daily requirement of water is at least 1 liter per day, with 2 liters being better
• Fluorine is added to water for dental health, while chlorine is added to purify water
• It is considered better to drink water between meals
• Vitamin B is necessary for the breakdown of carbohydrates, Vitamin C is necessary for the correct absorption of iron, and Vitamin D is necessary for the absorption of calcium and phosphorus
• The body requires minerals in small amounts for a number of different functions.
• Minerals:

  • each mineral is required in different amounts
  • there are 17 minerals in total
  • make up 3% of body weight
• Major (Macro) minerals:

  • required in larger amounts (over 100 mg. daily ) 
• Trace elements:

  • required in very small amounts (less than 100 mg. daily)
• Absorption rate can vary:

  • calcium 30%
  • sodium almost 100%
• Calcium:

  • the body contains more calcium than any other mineral in the body.
  • the skeleton contains about 99% of the body’s calcium with approximately 1kg present in adult bones.
• Calcium functions:

  • develop and maintain healthy bones and teeth
  • normal muscle contraction (including the heart)
  • normal blood clotting
• Calcium levels in the blood are carefully regulated by hormones such as vitamin D to keep it within narrow limits
• Low calcium intake:

  • if calcium intake is too low, calcium is withdrawn from bones to maintain blood levels
  • a diet low in calcium can lead to low bone density which, over time, can lead to osteoporosis
  • Osteoporosis is characterised by weak and brittle bones
  • low calcium intakes are often seen in teenage girls
• Calcium sources:

  • dairy products
  • bread as most bread flour (except wholemeal) is fortified with calcium by law in the UK
  • green leafy vegetables such as broccoli, cabbage
  • fortified soya products
  • fish eaten with the bones e.g. sardines, tinned salmon.
• Calcium deficiency:

  • reflected in bone density not low blood levels
  • bone acts as a reservoir in times of need
  • insufficient calcium in bones can be a result of an inadequate supply of vitamin D (it is essential for  the absorption of vitamin D)
  • in children this can result in rickets, and osteoporosis in adults
• Recommended Daily Allowance: (calcium)

  • Adolescents: 1200 m.g
  • Children: 1000 m.g.
  • Adults:   800 m.g.
• Calcium absorption:

  • inhibitory factors include phytates (e.g. in wholegrain cereals, pulses) and oxalate (e.g. in spinach, beetroot)
  • promoting factors include vitamin D, lactose and dietary protein.
• Sodium is a component of salt, also known as sodium chloride
• Sodium Chloride RDA: 4 grams per day
• To convert sodium to salt, multiply by 2.5
• Sodium Chloride functions: (table salt)

  • regulating body water (correct water balance)
  • absorption of certain nutrients and water from the gut
• Sodium levels are under homeostatic control, regulated by the kidneys

  • when supply is excessive, sodium is excreted in urine.
• Sodium Chloride sources:

  • most raw foods contain sodium chloride (NaCl) in small amounts, yet salt is commonly added to food during processing, preparation and serving.
• Intakes of sodium are considered to be too high in Ireland, deficiency is unlikely to occur.

  However, losses can occur:

  • excess sweating
  • diarrhoea
  • renal failure (when the kidneys become unable to filter waste material)
• Sodium sources:

  • salt added in cooking
  • salt in foods as a preservative (e.g. bacon)
  • smoked fish
  • cheese
  • conv. Soups/ sauces
  • crisps
  • occurs naturally in foods
• 80% of our salt intake is from processed foods

  10% is from salt occurring naturally in foods
• Sodium forms part of M.S.G. - Monosodium glutamate (flavour enhancer)