Nutrition

 by: Rita Preece

What is protein?

Millions of different proteins occur in nature. Protein is made of chains of amino acids held together by peptide bonds. There are about 20 amino acids that can be bound together in various combinations to make the millions of different proteins. There are two groups of amino acids: non-essential amino acids, which are made by your body and essential amino acids, which have to come from your food.

Why does my body need protein?

Protein is an important part of muscle fibre, cell walls, skin, nails and hair. You are losing protein all the time as you shed dead skin cells, nails and hair and it has to be replaced. At times your body needs more protein, like when you're growing, when you're pregnant or breast-feeding, or when wounds are healing. Protein is a source of energy for your body and the amino acids are used to make things like adrenaline and antibodies to fight disease.

How does my body digest the protein I eat?

When you eat protein, your body's digestive system breaks it down into its component amino acids. These are absorbed into your bloodstream through the walls of your small intestine and your liver. Your body puts the amino acids together in whatever combinations it needs, e.g. to make hair protein or new skin cells. Proteins include nitrogen molecules and one of the byproducts of digesting proteins is ammonia. This is converted into urea which is filtered by the kidneys and passed as urine.

How much protein does my body need?

Health authorities in the U.S.A., Canada and Australia recommend a daily intake of 0.75 - 0.8 grams of protein per kilogram of bodyweight. If you weigh 80 kilograms, that's 60 grams of protein a day. High protein (or low carbohydrate) diets will recommend more.

Can my body store protein?

No. You need to eat the protein your body needs every day. Any excess protein is converted into urea and passed as urine.

Are all proteins the same?

Different proteins are made up of various combinations and amounts of amino acids. Proteins from animals, fish, poultry, soy and Amaranth contain all of the essential amino acids and are they are easily digestible. Proteins from plants and grains do not usually have all of the essential amino acids and you need to eat a selection of them to get all the amino acids you need.

What if I don't eat enough protein?

Most people eat more than enough protein. If you don't eat any animal products, you should eat a wide variety of plant and cereal foods. Some symptoms of protein deficiency are: poor growth, weight loss, muscle wasting, iron deficiency, swollen feet and ankles.

Is it dangerous to eat too much protein?

There are risks associated with following a high protein diet for a long time. Your kidneys have to collect and filter more toxic byproducts. This may affect the function of your kidneys, particularly if you have diabetes. It is possible for calcium to be lost from your body. If animal products are your main source of protein, you should avoid those that are high in saturated fats and cholesterol because they will increase the risk of a number of diseases including heart disease.