One of the first questions people ask vegetarians and vegans (aside from, "but don't you miss steak?") is: "where do you get your protein?"
While protein is an important macronutrient, it's entirely possible to get enough protein from plant sources.
"The human body is made up of approximately 20 percent protein, including brain cells, muscle, skin, hair and nails. Protein is an essential nutrient, meaning your body doesn't store protein well, so it's important to get enough from your diet each day," Robbie Clark, dietitian and sports nutritionist, told The Huffington Post Australia.
The primary difference between animal and plant protein is that animal proteins are a "complete" protein, while most plant proteins are not.
"There are 20-22 different amino acids commonly found in plant and animal proteins. The body can only manufacture some of these amino acids, meaning the rest must be supplied by the diet," Clark said.
"The main difference between animal and plant protein is their amino acid profiles.
The amino acid profile of animal proteins is closer to that found in humans and are considered to be complete proteins, which means they provide all the essential amino acids in the right ratios compared to the incomplete proteins found in a majority of plant sources.
"For example, some key plant proteins are often low in methionine, tryptophan, lysine and isoleucine. This also means the proteins in animal foods are used more readily and rapidly by the body."
In saying this, if you have made the choice to not eat meat, it doesn't necessarily mean you can't get enough protein in your diet.
Protein isn't only found in meat, fish, eggs and dairy products -- protein is present in most plant foods, to varying degrees. You just have to make sure you're eating a wide variety of protein-rich plant-based foods, according to Clark.
"If you avoid animal foods, then it may be slightly more challenging to get all the protein and essential amino acids that your body requires, especially if your diet lacks variety," Clark told HuffPost Australia.
"However, vegetarians and vegans can obtain enough of all the essential amino acids by eating a variety of different types of plant foods including legumes, grains, nuts, seeds, soy products and vegetables."
According to Clark, tempeh, tofu and legumes are especially important to include.
"One essential amino acid which may be difficult for vegetarians and vegans to obtain is lysine, as only a few vegan foods contain lysine in large amounts, for example tempeh, tofu and legumes," Clark said.
There may be also some circumstances where a plant-based protein supplement is beneficial.
"People who require higher intakes of daily protein or struggle to meet their daily requirements -- such as athletes, injured or chronically ill, the elderly and those with a low appetite or fussy eaters -- may be encouraged to add plant protein powders into their diet," Clark told HuffPost Australia.
Here are some great sources of plant-based protein:
1. Legumes -- such as chickpeas, lentils, kidney beans, borlotti beans, soybeans and peanuts.
"These are not only a great source of protein but also contain good amounts of fibre, carbohydrate, vitamins and minerals," Clark said.
2. Nuts -- such as almonds, walnuts, pecans, cashews, Brazil nuts and nut butters.
"These foods are also a good source of fibre, iron, vitamin E, selenium and zinc, which is important for immunity and prostate health, and healthy fats are good for heart health."
3. Seeds -- such as sunflower seeds, chia seeds, flax seeds, sesame seeds, chia seeds, hemp seeds and pumpkin seeds.
"These are all mineral rich and contain healthy fats such as omega-3s," Clark said.
4. Grains -- such as quinoa, buckwheat and amaranth.
"These ancient grains are gluten free and are also a good source of fibre and low glycaemic index carbohydrate."
5. Soy Products -- such as tempeh, organic tofu and edamame.
"These foods contain soy and are considered complete proteins (containing all amino acids)," Clark said. "These foods also contain good amounts of fibre and healthy fats."
We know protein is important, but how much do we really need?
"The amount of protein you require in your diet on a daily basis depends on your weight, age, health status and activity levels," Clark said.
"As a rough guide, the recommended dietary intake for protein (measured in grams per kilogram of bodyweight) for different population groups is:
- 0.75 g/kg for adult women
- 0.84 g/kg for adult men
- 1.07 g/kg for men aged over 70
- 0.94 g/kg for women aged over 70
- Around 1.0 – 1.1g/kg for pregnant and breastfeeding women, and for men and women over 70 years
- Elite endurance athletes: 1.6 g/kg
- Resistance athletes (early stage): 1.5-1.7 g/kg
- Resistance athletes (steady state): 1.0-1.2 g/kg
- Football, power/contact sports: 1.4-1.7 g/kg