Protein is made up of chains of molecules called amino acids.

There are 20 different types of amino acids, each with a specific function in the body.

Some amino acids are essential for adults and children. The body cannot make these amino acids. These are called essential amino acids.

All the other amino acids can be made from the protein eaten in other foods.

As the vegetarian market grows, there is a large range of food products made from soya, such as soya mince, textured vegetable protein (TVP) and tofu.

High biological value foods include milk, meat and poultry, cheese, soya, Quorn, eggs and fish.

Foods that contain all the essential amino acids are said to have high biological value.

Low biological value proteins can be easily combined in a meal or product to provide all of the essential amino acids.

Low biological value foods include nuts, pulses, rice, lentils, beans, seeds and cereals.

Foods that do not contain all of the essential amino acids are said to have low biological value.

Examples of food combining/protein combining include: - beans on toast, dhal and rice + hummus and pitta bread

Vegetarian, vegan or limited diets rely on combining LBV proteins.