A baby is born with relatively little protein compared to brain tissue but the body of a 70kg (11 stone) man contains about 11kg of protein. When you look at it this way, it is easy to understand why eating a protein-rich diet is essential.

In the most recent survey of Irish eating habits (IUNA, 2000), protein intakes were more than adequate in most people. Meats, dairy products and breads provided two-thirds of the protein consumed.

Different types of protein
Protein is made up of small sub-units called amino acids, which are linked together to form chains. Different proteins in the body have their own unique sequence of amino acids so, for example, the hormone insulin will have a completely different arrangement of amino acids to oestrogen or testosterone.

Some proteins have as little as two amino acids and some have thousands in their sequence. Some amino acids are essential because they cannot be made by the body and therefore must be supplied in the diet so that all the various structural functions of proteins can be met. Usually, only very limited, cereal-based diets, do not contain the range of essential amino acids.
How much do we need?

The amount of protein required by adults and children is estimated according to their current weight, and the value is described as the amount of protein in grams per kilogram of body weight that must be eaten each day. The amount needed for health also varies with age; naturally, younger children have higher needs than teenagers who in turn have higher needs than adults, because both children and teenagers are growing.

In children boys have higher requirements than girls and this reflects the different musculature and physical appearance of boys and girls. Exercise increases protein requirements, as does illness, injury and disease.

There is a reserve of protein in the body and it is thought that this is probably housed in the liver. This reserve helps to preserve body protein in muscle and in major organs and compensates for low dietary protein intakes that may occur from day to day.

Protein requirements

During the second half of pregnancy and while breastfeeding women need an additional 10g protein/day.

Protein requirements taken from the Food Safety Authority of Ireland Recommended Dietary allowances for Ireland, 1999.

High protein foods

Protein is found in both animal and vegetable foods. Animal foods such as milk, eggs and meat contain all of the essential amino acids necessary for growth. Vegetarian diets need to combine cereal protein with beans and pulses to ensure the correct complement of amino acids for growth.