1. Section A: Nutrition
Topic 5: Protein
L.O To understand the use and importance of protein in the diet.

2. Protein Learning objectives
To develop a knowledge and understanding of:
The structure of proteins, including the difference between high biological value and low biological value proteins
The functions of proteins in the diet
The main sources of protein in the diet
What happens if we have a deficiency or excess of protein in our diet.
OCR GCSE Food Preparation and Nutrition

3. Structure of proteins Protein is a macronutrient.
Protein is made up of complex chains of molecules called amino acids.
There are 20 different types of amino acid, each with a specific function in the body.
Some amino acids are essential for adults and children. These must be provided in foods as the body cannot make these amino acids.
All the other amino acids can be made from the protein eaten in other foods.
OCR GCSE Food Preparation and Nutrition

4. High biological value protein
The foods that contain all the essential amino acids are called high biological value (HBV). These come from animal sources (meat, fish, poultry and dairy products) plus the vegetable source, soya. Foods made from soya include soya mince, textured vegetable protein known as TVP, tofu and Quorn®, which is the brand name for a food product made from mycoprotein.
OCR GCSE Food Preparation and Nutrition

5. Low biological value protein
Foods that do not contain all the essential amino acids are said to have low biological value (LBV). Low biological value sources of protein include cereals, peas, beans, pulses, nuts and seeds. Low biological value proteins can easily be combined in a meal or product to provide all the essential amino acids. This is called food combining or complementary proteins.
OCR GCSE Food Preparation and Nutrition

6. Functions of protein in the diet
Protein is used for growth, especially in children and pregnant women. It is used to repair body tissue after illness, accidents and surgery, and for renewal of cell proteins for people of all ages. Enzymes vital for metabolism are composed of proteins. Hormones, which regulate some important bodily functions, are also composed of protein. They provide a secondary source of energy. When the body has used all the amino acids it needs for construction, the remainder are ‘burnt’ for energy.
OCR GCSE Food Preparation and Nutrition

7. How much protein do we need?
The daily reference nutrient intake for children is: For adults the RNI is 0.75 g of protein per kg of body weight. Pregnant and lactating women need more protein.
OCR GCSE Food Preparation and Nutrition

8. Deficiency of protein
Protein deficiency is rare in the developed world.
However, not eating enough protein can cause various problems:
In children, growth slows down or stops.
Digestive upsets are caused as enzymes are not produced.
The liver fails to function normally.
Muscles become weak, so limbs are thin and the tummy is soft and may look distended.
OCR GCSE Food Preparation and Nutrition

9. Sources of protein in the diet
Animal sources include all meats, such as poultry, offal and game, as well as fish, cheese, milk, eggs and gelatine. Vegetable sources include soya beans and soya products, pulses, beans, cereal grains and cereal products, nuts and Quorn®.
OCR GCSE Food Preparation and Nutrition

10. Key words
Macro nutrient: needed by the body in large amounts. Amino acids: the smallest units of a protein. Essential amino acids: these must be provided by food as they cannot be made by the body. High biological value proteins: contain all the essential amino acids. Low biological value proteins: do not contain all the essential amino acids.
OCR GCSE Food Preparation and Nutrition

11. Key words
Food combining: mixing different low biological value proteins to supply all the essential amino acids. Complementary proteins: mixing different low biological value proteins to supply all the essential amino acids.
OCR GCSE Food Preparation and Nutrition