Protein Flashcards
Composition of protein
1. Carbon (C)
2. Hydrogen (H)
3. Oxygen (O)
4. Nitrogen (N)
- Protein is the only nutrient that contains nitrogen (N). This element is needed for the growth and repair of every cell in the body.
What is protein made up of?
Protein is made up of a chain of smaller units called amino acids. Amino acids are linked together by peptide links.
Enzymes
Enzymes are substances that help chemical reactions. During digestion, enzymes break down amino acids.
Classification of protein
1. High biological value (HBV) proteins
2. Low biological value (LBV) proteins
High biological value (HBV) proteins
These are proteins that contain all or most of the essential amino acids needed by the body. Essential amino acids are those the body cannot make itself, so they must come from food. Most HBV proteins are found in animal sources, e.g. meat.
Low biological value (LBV) proteins
These are proteins that do not contain many essential amino acids and usually come from plant sources, e.g. cereals.
Sources of protein
HBV protein foods:
- Meat
- Fish
- Eggs
- Cheese
- Milk
- Yoghurt
- Soya beans
- Meat alternatives
LBV protein foods
- Peas
- Nuts
- Beans
- Lentils
- Cereals
Reference intake for protein
Adults need at least 50g of protein, or approximately 0.75g for every 1kg of body weight. Children and teenagers need more because they are growing so quickly.
Functions of protein
- Protein is needed for the growth and repair of all body cells (skin, blood, tissues and bones)
- It produces heat and energy
- It is necessary for the production of important substances in the body, e.g. hormones, enzymes and antibodies (which fight disease).
Protein deficiency symptoms
- poor or stunted growth with muscle waisting
- slow healing of wounds
- hair breakage and loss
- poor general health
- hormone and enzyme imbalances
Amino acids
Can't be made by the body, have to be from foods
