Home Economics, Minerals, Leaving Cert

Terms in this set (...)

Definition of Minerals
They are inorganic nutrients. The human body requires about 20 mineral elements to protect against diseases. They are required in small amounts. Those required in minute quantities are referred to as trace elements.
Major Minerals
Calcium (Ca)

Phosphorus (P)

Sodium (Na)

Potassium (K)

Magnesium (Mg)

Chloride (Cl)
Trace Mineral elements
Iron (Fe)

Zinc (Zn)

Iodine (I)

Copper (Cu)

Selenium (Se)

Fluorine (F)
Definition of Calcium
It is the most abundant mineral in the human body. About 99% is present in bones and teeth, and the remainder in blood, muscles and nerves. Classification is the term for te hardening of bones and teeth. This is due to the absorption of calcium and phosphorus (calcium phosphate).
Sources of Calcium
Milk, cheese, yoghurt

Canned fish, e.g. sardines, salmon

Leafy green vegetables, e.g. cabbage, spinach

Seasame seeds

Fortified flour

Hard water
Calcium content of foods (100g) - Cheese
800 mg
Calcium content of foods (100g) - Sardines (canned)
550 mg
Calcium content of foods (100g) - Milk
103 mg
Calcium content of foods (100g) - Bread (white)
100 mg
Calcium content of foods (100g) - Spinach
100 mg
RDA Calcium for Children
RDA - 800 mg
RDA Calcium for Adolescents
RDA - 1200 mg
RDA Calcium for Pregnancy/ lactation
RDA - 1200 mg
Functions for Calcium
Plays an important role in the formation of strong bones and teeth.

Is required for blood clotting and to regulated blood pressure.

Is necessary for normal muscle contractions, e.g. regular heartbeat.

Is required for normal nerve funtion.
Calcium deficiency can cause...
Rickets in children and osteomalacia in adults in severe cases.

Osteoporosis in children, teenagers and adults.

Severe osteoporosis in the elderly.

Tooth decay and poor quality teeth.

Poor blood clotting.

Muscular spasms.

Disturbance in functioning of nerve cells.
Absorption of Calcium
Only between 20-30% of calcium in the diet is absorbed. Certain factors may assist or hinder calcium absorption.
Assisting Calcium absorption
Sufficient vitamin D in the diet is essential for calcium absorption.

Parathormone, a hormone produced by the parathyroid gland, controls the levels of calcium in the blood.

Oestrogen, a hormone in premenopausal women, promotes calcium absorption.

Phosphorus, which combines with calcium to form calcium phosphate, must be present in the correct proportions.

An acid enviroment aids calcium absorption. This can be enhanced by combining vitamin C with calcium foods.

Protein is necessary for calcium absorption - the calcium is absorbed into the blood stream by becoming bound to protein.
Hindering Calcium absorption
Phytates acid, present in wholegrain bread and cereals, may combine with calcium, preventing its absorption.

Oxalaes/ oxalic acid present in rhubarb and spinach may react with calcium inhibiting its absorption.

Tannins in tea and coffee inhibit calcium absorption.

Excess protein results in calcium being excreted in the urine.

Incorrect calcium/ phosphorus ratio inhibits calcium absorption.

Research indicates that over-consumption of soft drinks inhibit calcium absorption.
Definition of Iron
Over half of the iron present in the human bod is in the blood. The remainder is stored in te liver, spleen and bone marrow, with a small proportion in muscle protein and cell enzymes.
Sources of Iron
Liver, kidney, red meat

Wholegrain flour

Dark green vegetables, eg. spinach, cabbage


Iron content of foods - Liver (lamb's, fried)
11 mg
Iron content of foods - Kidney (pig's, fried)
9 mg
Iron content of foods - Wholegrain flour
4 mg
Iron content of foods - Spinach (boiled)
4 mg
Iron content of foods - Eggs (boiled)
2 mg
RDA Iron for Children
RDA - 8 mg
RDA Iron for Adolescents
RDA - 14 mg
RDA Iron for Adults
RDA - 10 mg
RDA Iron for Pregnancy/ lactation
RDA - 15 mg
Functions of Iron
Is essential for the formation fo the pigment haemoglobin in the red blood cells.

Haemoglobin transports oxygen around the body.

Is involved in myoglobin production which carries oxygen to the muscles.

Works with enzymes to release energy from food.
Iron deficiency causes...
Tiredness, lack of energy

Muscle tire easily



Anaemia in severe cases
Definition of Anaemia
It is a disease caused by the shortage of haemoglobin, as a result of insufficient iron in the diet, or an inability to absorb iron. It is more common in females due to menstruation. Symptons include tiredness, dizziness, headaches, paleness, shortness of breath and loss of appetite.
Absorption of Iron
Only about 15% of the iron present in the diet is absorbed. However, the body adjusts and absorbs more times of special need, e.g. growing childrena dn pregnant women. Certain factors may assist or hinder iron absorption.
Assisting Iron absorption
The sources of iron - the iron in meat and offal called haem iron is more easily absorbed than non-haem iron from plant sources.

The presence of vitamin C (absorbi acid promotes the absorption of non-haem iron. It reduces ferric iron to te absorbable ferrous state.

Eating animal and plant sources of iron together helps the body absorb more non-haem iron.
Hinderin Iron absorption
Excess fibre in the diet decreases iron absorption.

Tannis in tea and coffee reduce iron absorption.

Choosing only non-haem sources of iron results in little being absorbed.

Phtates present in wholegrain breads and cereals combine with iron preventing absorption.

Oxalates present in rhubarb and spinach react with iron inhibiting its absorption.
Sources of haem Iron

Red Meat

Meat products

Sources of non-haem Iron


Green vegetables


Fish (Although the iron is non-haem iorn a property in fish boosts iron absorption)
Source of Potassium
Pulses, green leafy vegetables

Bananas, oranges



Fruit juices, nuts
Functions of Potassium
Maintains fluid balance in body tissue.

Healthy nerve activity.

Normal muscle contractions.
Effects of deficiency (Potassium)
Very rare (potassium is present in many foods).

Mental confusion.

Cardiac arrest.

Muscular weakness.
RDA Potassium
0.8 - 3.1 g
Sources of Sodium
Table salt

Processed foods

Smoked and cured meat and fish

Meat products


Snack foods
Functions of Sodium
Maintains fluid balance in body tissue.

Healthy nerve activity.

Normal muscle contractions.
Effects of deficiency (Sodium)
Muscular weakness and cramps.

Low blood pressure.

Lost of appetite.
RDA Sodium
RDA - 1.6 g
Sources of Zinc
Meat and meat products





Functions of Zinc
Enzyme activity.

Protein and carbohydrate metabolism.

Normal hormone activity.

Healthy skin and hair.
Effects of deficiency
Frequent infections.

Reduced appetite.

Delayed healing.

Dry skin.
RDA Zinc
RDA - 7-12 mg
Sources of Iodine

Cod live oil

Iodised salt

Vegetables grown in iodine-rich soil
Functions of Iodine
Production of thyroid hormone/thyroxine.

Regulation of growth and development.

Regulates metabolism.
Effects of deficiency (Iodine)
Goitre, enlargemen of the thyroid glad due to deficiency of thyroid hormones.

Retarded mental development.


Weight loss.
RDA Iodine
70-160 μg
Retaining Minerals and Vitamins in Fruit and Vegetables
Choose good-quality fresh foods, avoid prepared produce.

Buy in small quantities and avoid storing fresh fruit and vegetables for prolonged periods.

Store fruit and vegetables in a cool, dry, dark place.

Eat fruit and vegetables raw if possible.

Avoid peeling fruit and vegetables or peel thinly. Prepare food shortly before use.

Avoid steeping.

Use a sharp knife to reduce the effect of the enzyme oxidase.

Begin the cooking of vegetables of vegetables in boiling liquid.

Cook for the shortest time possible.

Cook in the minimum amount of liquid.

Cover the saucepan.

Use liquid for sauces or gravy.

Do not use bread soda to soften green vegetables.

Serve immediately, avoid keeping warm.

Avoid reheating.