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Minerals | Water | Vitamins | Links
Minerals
Minerals are inorganic substances simpler than vitamins.
They are classified as follows:
- Macro-minerals: calcium, phosphorus, sodium, potassium, magnesium
- Trace elements: iron, iodine, fluorine, zinc, manganese
Example
|
Calcium |
Sodium |
Iron |
Classification
|
Macro-mineral |
Macro-mineral |
Trace element |
| Functions |
- Combines with phosphate to strengthen bones and teeth.
- Works with vitamin K in blood clotting.
- Ensures correct working of muscle and nerves.
- Maintains healthy teeth.
|
- Maintains water balance in the body.
- Keeps blood and body fluids alkaline. |
- Combines with oxygen and carries it around the body.
- Component of haemoglobin. Gives blood its red colour. |
| Sources |
Milk
Cheese
Bread
Bones of tinned fish |
Table salt
Bacon
Cheese
Fish
Snack foods
|
Red meat, especially liver
Pulse vegetables
Green leafy vegetables
Dried fruits
Nuts |
| RDA |
Adult: 800mg Teenager: 1200mg Pregnant women: 1200mg.
Young children: 1000mg
|
2-2.5g per day |
Child: 10mg Women: 12-15mg Pregnant women: 15-18mg
Men: 10-12mg |
| Deficiency |
- Poor growth
- Poor bones and teeth
- Rickets
- Osteomalacia (adult rickets)
|
Muscle cramp
Loss of appetite |
Anaemia
General ill health |
Iron absorption
The amount of iron that is absorbed from food depends on the form of iron that is present in the food:
Haem Iron (Fe2+)
myoglobin in meat, fish or muscle tissue; 15-25% is absorbed
Non Haem Iron (Fe3+)
iron in plant foods e.g. cereals, legumes and leafy vegetables; 8% is absorbed
The iron in plant food is mostly present as insoluble complexes of Fe3+ with phytic acid, oxalates, phosphates and carbonates.
Ascorbic acid favours the reaction from Fe3+ to Fe2+ which makes it easier to absorb.
Sugars, citric acid and amines increase iron absorption (non haem).
Hydrochloric acid in the stomach - converts non haem to haem iron.
Phytate, oxalis acid and tannin bind with iron and decrease its absorption.
The efficiency of iron absorption rises when the body’s reserves are low, and vice versa.
Water
Composition
|
Hydrogen and oxygen
Ratio 2:1
|
| Functions |
- Component of all cells
- Transports substances around the body, e.g., carbon dioxide and nutrients
- Source of minerals, e.g., calcium and fluorine
- Regulates body temperature
- Removes waste from the body
|
| RDA |
2 - 2.5 litres per day
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Vitamins
Vitamins are classified as follows:
Fat soluble - vitamins A, D, E, K (usually found in foods that contain fat). All fat soluble vitamins are stored in the liver.
Water soluble - vitamin B group, C (will dissolve in water).
Vitamin A
Types
|
Retinol |
Carotene (provitamin) |
Classification
|
Fat soluble |
| Functions |
- Needed to form pigment rhodopsin
- Needed for health of epithelial tissues, skin and membranes
- Needed for healthy skin
- Needed for optimum growth
|
| Properties |
- Insoluble in water
- Soluble in fats
- Fairly stable to heat
- Destroyed by oxidation
- Drying causes serious loss
|
| Sources |
liver
fish liver oils
herrings
butter
margarine
egg yolks
|
carrots
dark green vegetables
spinach
peas
cabbage
apricots |
| RDA |
- Children: 300-750mg
- Adults: 750mg
- Pregnant women and nursing mothers: 750-1200mg
|
| Deficiency |
- Night blindness
- Damage to mucous membranes
- Dry and scaly skin
- Xerophthalmia (eye disease) common in Third World
- Retarded growth
|
Vitamin D (calciferols)
| Types |
Ergocalciferol - produced by light |
cholecalciferol - dehydrocholesterol is produced by sunlight
|
| Classification |
Fat soluble
|
| Functions |
- Absorption of calcium and phosphorous
- Builds bones and teeth
|
| Properties |
- Insoluble in water
- Soluble in fats
- Not destroyed by heat or oxidation
- Resistant to acids and alkalis
|
| RDA |
- Children: 10mg
- Adults: 2.5mg
- Pregnant women and nursing mothers: 10mg
|
| Deficiency |
- Osteomalaria (depletion of calcium and phosphorous). Can occur during pregnancy, when mothers are breastfeeding and in old age
- Poor teeth development
- Rickets: a childhood disease due to non-absorption of calcium and phosphorous
|
Vitamin E - tocopherols
| Classification |
Fat soluble
|
| Functions |
- Anti-oxidant
- Improves fertility (in rats)
|
| Sources |
Oils and margarines
Whole grains
Liver
Fruit and vegetables
|
| RDA |
None, as the vitamin is widely available in many foods
|
| Deficiency |
Is rare
|
Vitamin K (quinones)
| Classification |
Fat soluble
|
| Functions |
Formation of prothrombin for blood clotting
|
| Properties |
- Stable to heat, air and moisture
- Not resistant to light
- Cooking destroys a little
|
| Sources |
- Green leafy vegetables, e.g., lettuce, spinach, cabbage
- Egg yolk
- Liver
- Synthesised by bacteria in the intestine
|
| RDA |
Deficiency is rare
|
Deficiency
(rare) |
- Haemorrhaging under skin- Internal bleeding |
Vitamin C (ascorbic acid)
| Classification |
Water soluble
|
| Functions |
- Necessary to form collagen
- Promotes healing
- Maintains strength in blood vessels
- Helps absorption of iron
- Protects against infection
|
| Properties |
- Most unstable of all vitamins
- Destroyed by oxidation.This is accelerated by bruising, chopping and drying.
- Water soluble
- Food value lost in storage
- Destroyed by heat
- Destroyed by alkali
|
| Sources |
Strawberries
Citrus fruits
Melon
Rose-hip syrup
Milk
Green leafy vegetables, e.g., cabbage, broccoli and brussel sprouts
|
| RDA |
- Children and adolescents: 40-60mg per day
- Adults: 60mg per day
- Nursing mothers: 80-100mg per day
|
| Deficiency |
- Degeneration of body tissues, skin and teeth
- Retarded growth
- Pains in limbs and swollen joints
- Listlessness, restlessness and irritability
- Delay in healing
- Scurvy
- Anaemia
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Vitamin B group
| Example |
Thiamine B1
|
Riboflavin B2 |
| Functions |
- Releases energy from food
- Promotes growth
- Prevents beri-beri
|
- Aids metabolism of energy foods
- Promotes welfare of the body |
| Properties |
- Lost in preservation and cooking
- Water soluble
- Destroyed by alkali, dry heat and milling
|
- Lost during cooking and canning
- Water soluble
- Destroyed by alkalis and sunlight |
| Sources |
Wholegrains
Pulse vegetables
Nuts
Pork
Liver, Heart, Kidneys
|
Liver
Milk, cheese, eggs
Meat
Dried yeast |
| RDA |
1-1.5 mg per day
|
1.2 -1.7mg per day |
| Deficiency |
- Beri-beri
- Poor appetite
- Slow growth
- Muscle cramps
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- Skin abnormalities
- Poor vision
- Slow growth |
Links
A PowerPoint presentation on the fat and water-soluble vitamins. Excellent for teachers.
http://iweb.tntech.edu/abrunt/chp-7/index.htm
Covers the sources of calcium, daily requirements, frequently asked questions, etc.
http://www.calciuminfo.com/s_topics.htm
An index to everything you wanted to know about minerals, sources, deficiencies, RDA, functions and toxicity.
http://nutrition.about.com/health/nutrition/
library/blminerals.htm
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