Every cell in your body is built from and powered by what you eat. A balanced diet supplies carbohydrates, fats, proteins, vitamins, mineral ions, fibre and water in the amounts your body needs. Leave one out for long enough and a deficiency disease follows.
A balanced diet contains all the nutrients (carbohydrates, fats and oils, proteins, vitamins, mineral ions, fibre and water) in the correct proportions and amounts to stay healthy, and supplies enough energy for the person's needs. Scurvy is caused by a lack of vitamin C; rickets is caused by a lack of vitamin D or calcium.
Fill the plate in the sim with a day's food. Each bar shows how much of a teenager's daily need one nutrient reaches, and the white line marks 100%. A diet built from one or two foods always leaves some bars short.
A balanced diet is not just "eating healthy food" or "eating a bit of everything". You must say it contains all the nutrients in the correct proportions (amounts).
Four quick checks. Each correct answer earns XP and records this skill on your profile.
In the diet sim, what does the white line across each nutrient bar mark?
Which food in the sim would best raise a low vitamin C bar?
The sim warns that the plate is short of calcium. Which deficiency disease does it name?
The sim reports too little fibre. What problem does it link to this?
For each nutrient learn one or two good sources and why the body needs it. The foods in the sim are chosen to be rich in particular nutrients: try the plate with and without each one.
| Nutrient | Principal sources | Importance |
|---|---|---|
| Carbohydrates | rice, bread, potatoes, pasta | main source of energy for respiration |
| Fats and oils | butter, cooking oil, cheese, oily fish | energy (about twice as much per gram as carbohydrate), energy store, insulation, cell membranes |
| Proteins | meat, fish, eggs, beans | growth and repair of cells; making enzymes, antibodies and haemoglobin |
| Vitamin C | citrus fruit (oranges), broccoli, fresh vegetables | keeps skin, gums and blood vessels healthy; helps wounds heal |
| Vitamin D | oily fish, eggs; made in the skin in sunlight | helps the body absorb calcium, for strong bones and teeth |
| Calcium | milk, cheese, yoghurt | strong bones and teeth; blood clotting; muscle contraction |
| Iron | red meat, liver, beans, dark green vegetables | making haemoglobin in red blood cells, to carry oxygen |
| Fibre (roughage) | wholemeal bread, vegetables, fruit, beans | adds bulk so the gut muscles can push food along (peristalsis); prevents constipation |
| Water | drinks and most foods | solvent for reactions and for transport in blood; lost in sweat and urine, so must be replaced |
Deficiency diseases are caused by a lack of a particular nutrient in the diet. Clear the plate in the sim and add only rice, bread and chicken: the vitamin C, vitamin D and calcium bars stay low and both warnings appear.
Rickets can be caused by a lack of vitamin D even when there is enough calcium in the diet, because vitamin D is needed to absorb the calcium. Name both possible causes.
Unlocks once the four checks above are done. Worth more XP, written to IGCSE Paper 2 and Paper 4 standard.
Which statement best describes a balanced diet?
Which pair correctly matches a nutrient with its main importance?
A child who rarely goes outdoors and drinks no milk develops bowed legs. The most likely cause is a lack of:
Why do the gums of a person with scurvy bleed?
This skill is now recorded on your profile. Keep the chain going.