Diet & Deficiencies (Cambridge (CIE) IGCSE Biology): Revision Note
Exam code: 0610 & 0970
Balanced diet
A balanced diet consists of all of the food groups in the correct proportions
The necessary food groups are:
carbohydrates
proteins
lipids
vitamins
minerals
dietary fibre
water
Food groups table
Food type | Function | Sources |
|---|---|---|
Carbohydrate | Source of energy | Bread, cereals, pasta, rice, potatoes |
Protein | Growth and repair | Meat, fish, eggs, pulses, nuts |
Lipid | Insulation and energy storage | Butter, oils, nuts |
Dietary fibre | Provides bulk (roughage) for the intestine to push food through it | Vegetables, whole grains |
Vitamins | Needed in small quantities to maintain health | Fruits and vegetables |
Minerals | Needed in small quantities to maintain health | Fruits and vegetables, meats, dairy products |
Water | Needed for chemical reactions to take place in cells | Water, juice, milk, fruits and vegetables |
Vitamin and mineral requirements table
Vitamin / mineral | Function | Sources |
|---|---|---|
Vitamin C | Forms an essential part of collagen protein, which is found in skin, hair, gums and bones | Citrus fruit, strawberries, green vegetables |
Vitamin D | Helps the body to absorb calcium (and so required for strong bones and teeth, see below) | Oily fish, eggs, liver, dairy products, also made naturally by the body in sunlight |
Calcium | Needed for strong bones and teeth and involved in blood clotting. Deficiency can lead to osteoporosis later in life. | Milk, cheese, eggs |
Iron | Needed to make haemoglobin, the pigment in red blood cells that binds oxygen to transport it around the body | Red meat, liver, leafy green vegetables (e.g. spinach) |
Varying dietary needs of individuals table
Factor | Dietary needs |
|---|---|
Age | The amount of energy that young people need increases towards adulthood as this energy is needed for growth. Children need a higher proportion of protein in their diet compared to adults as this nutrient is required for growth. Energy needs of adults decrease as they age. |
Activity levels | The more active, the more energy required for movement as muscles are respiring more to contracting more. |
Pregnancy | During pregnancy, energy requirements increase as energy is needed to support the growth of the developing foetus, as well as the increased mass that the mother needs to carry around. |
Breastfeeding | Energy requirements increase and extra calcium still needed to make high quality breast milk |
Scurvy & rickets
Scurvy
Scurvy is the name for a severe vitamin C deficiency
Scurvy is caused by a lack of vitamin C in the diet for over 3 months
Symptoms of scurvy include:
anaemia
exhaustion
spontaneous bleeding
pain in the limbs
swelling
gum ulcerations
tooth loss
Scurvy is a condition that was commonly seen in sailors between the 15th to 18th centuries
Long sea voyages made it very hard to access a ready supply of fresh produce rich in Vitamin C
Scurvy can be treated with oral or intravenous vitamin C supplements
Rickets
Rickets is a condition in children characterised by poor bone development
Symptoms of rickets include:
bone pain
lack of bone growth
soft, weak bones (sometimes causing deformities)
Rickets can be caused by a severe lack of vitamin D
Vitamin D is required for the absorption of calcium into the body; calcium is a key component of bones and teeth
The body can naturally produce a form of Vitamin D when a substance in the skin (derived from cholesterol) is exposed to UV radiation in sunlight
Vitamin D can also be found in some foods e.g. fish, eggs and butter
The treatment for rickets is to increase consumption of foods containing calcium and vitamin D
Alternatively, vitamin D supplements can be prescribed
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