Protein is a staple macronutrient in our diet and comes in a range of different animal and plant-based forms.
Although we associate protein with muscles, gym goers and protein powder, protein is important for more than just building muscles -- it supports our immune system and overall health, and helps build hair and skin.
While the body can make certain proteins, essential amino acids must be supplied by the food we eat. This is why it's important to eat a certain amount of protein each day.
What is protein and why do our bodies need it?
"Protein is the nutrient that is considered to be the 'building block' of our bodies and is therefore an essential part of our diets," Anna Debenham, accredited practising dietitian from The Biting Truth, told HuffPost Australia.
"We need it to build healthy skin, hair and blood. Protein is also needed for muscle repair and regulates many chemical reactions in the body. It's also a key player in helping our immune systems to fight off bugs."
"Protein is built from amino acids, so when it gets broken down in our bodies, it is broken down into amino acids," Debenham explained.
There are three types of amino acids:
- Essential amino acids -- cannot be made by the body and must be supplied by food. They do not need to be eaten at one meal. The balance over the whole day is more important;
- Nonessential amino acids -- made by the body from essential amino acids or in the normal breakdown of proteins;
- Conditional amino acids -- needed in times of illness and stress.
"Our bodies make amino acids in two different ways: either from scratch, or by modifying others. Some amino acids are known as essential amino acids, which means our bodies do not produce them and therefore we must obtain them from our diets. For optimal health, your body needs all the essential amino acids in the right ratios."
Which types of foods are high in protein?
Protein is found in both animal and plant-based foods -- although animal protein is more "bioavailable" than plant-based protein -- and it's easy to reach the daily recommended amount by eating a healthy, balanced diet.
"The primary difference between animal and plant proteins is their amino acid profiles, and it is these amino acid differences that influence the rate at which they are absorbed and used in the body." Alexandra Parker, accredited practising dietitian from The Biting Truth, told HuffPost Australia.
Protein is found in:
- Meat, chicken, fish
- Nuts and seeds
- Dried beans and lentils
- Dairy products such as milk, yoghurt and cheese
- Soy products
"Animal-based protein are absorbed much more readily and rapidly than plant-based proteins and they tend to deliver all the amino acids we need. Plant-based proteins such as fruits, vegetables, grains, nuts and seeds lack one or more essential amino acids."
As such, vegetarians and vegans should focus on eating a range of plant-based foods across the day.
"People who don't eat meat, fish, poultry, eggs or dairy products need to eat a variety of protein-containing foods each day in order to get all the amino acids needed to make new protein," Parker said.
How many grams of protein do men and women need per day?
The amount of protein needed per day varies, depending on factors such as age, gender and amount of physical activity being completed.
"The average sedentary adult requires about 0.8-1g of protein per kilogram of body weight per day. So for a 65kg female who does little physical activity, this would equate to between 52-65 grams of protein per day," Debenham said.
The body requires more protein during times of cell growth and repair such as: during childhood and teenage years; pregnancy and lactation and after illness or surgery.
"Men and women who regularly exercise have higher protein requirements -- 1.2-2g per kilogram per body weight."
How much protein is in an egg, chicken, tuna, beef, nuts, dairy and legumes
Protein is found in animal products like beef, pork, lamb, eggs, fish and poultry, as well as in plant-based foods like legumes, whole grains, nuts and seeds.
How much protein is in:
- 65g of beef, pork or lamb or 80g chicken = approximately 20-25g protein
- 30g nuts, seeds and nut/seed butters = approximately 10-15g protein
- 1 large egg = approximately 7g protein
- 100g tuna = approximately 30g protein
- 100-150g legumes = approximately 15-20g protein
- 2 slices of cheese = approximately 10g protein
- ½ cup of oats = approximately 7g protein
- 1 cup cooked quinoa = approximately 8g protein
- 100g tofu = 12-15g protein
- 100g yoghurt = approximately 10g protein
- 2 slices seedy whole grain bread = approximately 12g protein
- 1 tablespoon peanut butter = approximately 6g protein