Proteins

Did you know?

Lentils have high levels of proteins and contain dietary fiber, vitamin B1 and minerals.

What are proteins?

Proteins are the body’s main source of nitrogen - important for growth and development. They are responsible for a variety of bodily functions and, in humans, are made up of different combinations of 20 amino acids. The combinations result in 1000s of different protein molecules.

All amino acids must be present in the body in adequate amounts for normal growth and development. Those that cannot be made by the body, or not made quickly enough, are called essential (of which there are 9), and those that we can make are called nonessential.

Why are proteins important?

Enzymes, haemoglobin, some hormones and antibodies are just a few examples of the substances in our bodies that are made of protein molecules. They are also important for the building and repair of tissues and for many other functions.

Not enough protein in the diet leads to muscle wasting (including damage to the heart) and damage to the liver, pancreas and gut. The immune system and developing brain can be affected too.

A serious depletion of protein can be life threatening. A condition called protein-energy malnutrition (PEM) is common worldwide, causing the death of 6 million children a year. In countries like Australia and New Zealand, PEM is seen most commonly associated with wasting diseases and in the elderly who can’t eat enough. In countries that undergo periods of famine, populations are at risk of protein deficiency diseases, known as marasmus and kwashiorkor.

For a healthy person, eating an excessive amount of protein isn’t that much of a problem, although, it may mean you are likely to eat less of other foods that you should be eating to stay healthy, like fruits and vegetables.

For those with kidney or liver disease, excessive protein is not advised. And if you are eating a high protein diet for weight loss, you are less likely to eat vegetables and more likely to eat foods that contain fat; this could have an effect on your kidney function (leading to kidney stones) and your bones (where calcium may be excreted in high amounts), and may increase your risk of heart disease and certain cancers.

What foods contain protein?

Protein is present, in the form of amino acids, from a variety of foods: meat, seafood, milk, cheese and egg (complete proteins with all the essential amino acids), whole grains, rice, corn, beans, legumes, oatmeal, peas and nuts.

Vegetarians generally eat adequate amounts of protein due to dairy products, eggs, legumes, nuts, breads and cereals being rich in essential amino acids. However, if you are vegan, and do not eat diary products or eggs, it is important you eat a combination of different plant foods each day to make sure you get enough protein.

In New Zealand, we get our protein from eating beef and veal (14%); bread (11%); milk (10%); poultry and fish/seafood (both 7%); and bread-based dishes and pork (both 5%) [4]. Vegetables provide about 8%.

How much protein is good for you?

Protein should account for 11-15% of your daily kilojoules. The RDI, or recommended daily intake, is: 45g for women and 55g for men, based on eating 0.75g protein per kg per day, for healthy 19-54 year-olds; 45g for healthy men and women after age 54. Note: Those who are obese do not require a huge amount of extra protein – talk to your dietitian.

How much protein do Kiwis eat?

The National Nutritional Survey 1997 reports that most New Zealanders eat almost twice the amount of protein than that eaten by people in the UK, but very similar to the amount eaten by Australians. Our intake is 15-16% of total energy, instead of 11-15%. Females are eating an average of 71g/day (instead of 45g) and males 105g per day instead of 55g.

 How much protein do certain foods contain?

Tbsp = tablespoon