2.5 - Balanced Diet

The nutrient groups and their functions

• A balanced diet supplies all the essential nutrients the body needs, in the right proportions.
• There are several groups of nutrients, and because each has its own job, a healthy diet must include all of them in suitable amounts.

The seven nutrient groups

1. Carbohydrates - Found in pasta, rice, bread and sugar. They are the body's main source of energy.
2. Lipids (fats and oils) - Found in butter and oily fish. They provide energy, act as an energy store, insulate the body against heat loss, and protect the internal organs.
3. Proteins - Found in meat, fish and beans. Needed for the growth and repair of body tissue, and can also provide energy in emergencies.
4. Water - From food and drink. Needed for almost every process in the body; a constant supply replaces water lost in urine, in breathing and in sweat.
5. Dietary fibre (roughage) - Found in wholemeal bread and fruit. Not digested, but provides bulk that helps food move through the gut and keeps the digestive system working properly.
6. Vitamins - Needed in small amounts.
   • Vitamin A - From foods such as liver. Helps keep the eyes, skin and hair healthy.
   • Vitamin C - From fruit such as oranges. Needed for healthy tissue and the repair of body tissue.
   • Vitamin D - From eggs and oily fish. Needed so the body can absorb calcium; also made by the skin when exposed to sunlight.
7. Mineral ions - Needed in small amounts.
   • Calcium - From foods such as milk and cheese. Needed to make strong bones and teeth.
   • Iron - From foods such as red meat. Needed to make haemoglobin, the substance in red blood cells that carries oxygen.

Energy needs and the effects of dietary excess

• The amount of energy and the balance of nutrients a person needs isn't the same for everyone - it differs from person to person and changes over a lifetime.
• To stay healthy, the energy taken in from food needs to balance the energy the body uses.
• Different foods provide different amounts of energy:
  • Vegetables and fruit release only a little energy.
  • Confectionery and fatty dairy foods are very high in energy.

Energy and nutrient needs vary between people

• Active people (heavy physical work or lots of exercise) use up more energy, so need to take in more. They also need:
  • More protein to build and repair muscle.
  • More carbohydrate to fuel their activity.
  • More water to replace what's lost by sweating.
• Children and teenagers need plenty of energy and extra protein because they're growing and usually very active.
• Older, less active people need less energy.

Taking in too much energy causes weight gain

• If a person regularly takes in more energy than they use, the body stores the surplus as fat and they gain weight.
• Someone whose weight is well above the recommended weight for their height is classed as obese.

Taking in too much of certain nutrients over a long period brings its own health problems

• Too much sugar - Can lead to type 2 diabetes, obesity, and tooth decay.
• Too much fat - Can lead to obesity and to heart and circulatory disease.
• Too much salt - Can lead to high blood pressure.

Reading the nutritional information on food labels - the energy, sugar, fat, fibre, and salt per serving - lets a person compare foods and judge how they might affect their health.