Protein Requirements Explained: All You Need to Know

Plant-based diets are on the rise.

With increasing exposure on social media platforms, more and more people, including athletes, are opting for the diet. This has led to a great confusion of where plant-based dieters receive their protein?

A popular answer to this question is from plant-based protein supplements, most commonly in the form of powder. Being spoilt for choice, combined with an overwhelming amount of information displayed on social media, many people are left confused when choosing a natural and safe product that suits them and their tastebuds. Based on scientific literature, here's what you need to consider when it comes to choosing a plant-base protein powder. 

What is protein and why do we need it?

Protein is an essential macronutrient made up of different sequences of 20 different tiny building blocks called amino acids. Nine of these 20 are called essential amino acids (EAA), meaning that the body cannot make them and they must be obtained from the diet. Protein has a wide array of functions and is an important component of every cell in the human body.

When protein is introduced into our body from food, it undergoes complex digestive and absorption processes, that results in the tiny amino acids being broken apart. These amino acids then carry out a whole range of functions such as building and repairing muscle and other body tissues, wound healing, energy, creating hormones, and enzymes, and a whole bunch more. 

Protein Requirements

Unlike carbohydrates and fats, the human body cannot store amino acids, therefore we must continually supply our body with protein from our diet. In Australia the Recommended Daily Intake (RDI) for adults is 0.84 grams per kilogram of body weight and 0.75 grams per kilogram of body weight for males and females, respectively (3). 

For athletes or people with high levels of physical activity, infants, pregnant women during their second and third trimester, breastfeeding women and people over the age of 70, the RDI will slightly increase. 

Plant-Based Protein vs Animal Protein

There is a persistent misconception that plant protein is nutritionally inferior to that of animal protein. They may differ in terms of digestibility and amino acid profile, but plant protein can offer an abundance of extra nutrients, less nasties like saturated fats and cholesterol and generally is cheaper and safer. 

Not all plant protein offer an optimal level of all of the essential amino acids. Animal protein sources contain all of the essential amino acids, while plant protein is usually limiting in one. This is a perfect example of why we are taught from a young age to eat a varied diet. When we combine two or more plant foods with an incomplete amino acid profile, they will make a complete profile and form what we call a ‘complimentary protein’. For example, legumes are limiting in the amino acid methionine and rice is limiting in the amino acid lysine. If you combine the two they make a complimentary protein. When pairing different plant proteins and ingesting an appropriate amount, its quality will become comparable to that of animal protein (8).

Amazonia’s product Raw Protein Isolate is made from pea and brown rice protein, making a complete protein that promotes muscle growth, maintenance and repair.

Choosing a Protein Powder: What to consider?

The decision to use protein supplements is going to be individualistic and can be based on a number of things such as training load, goals, taste, daily energy requirements, diet, budget, medical conditions, life stages, and the list goes on. 

Everyone can obtain all the protein they require from a well-planned and well-varied diet. However, protein powders can be a beneficial part of an overall nutrition plan. When selecting a form of protein, whether it be from animal, plant or supplement, it should be based on its protein quality. Protein quality is defined by digestibility and its amino acid profile.  

Protein supplementation is popularly used for increases in muscle protein synthesis, to achieve greater gains in muscle mass and strength and improve overall physical performance. If this is your goal I would recommend selecting a protein supplement that has all of the essential amino acids and is particularly rich in the branched chain amino acids, leucine, valine and isoleucine. Numerous studies have shown that branch chain amino acids inhibit breakdown of skeletal muscle and promote muscle repair. Of these three amino acids, leucine has been shown to stimulate muscle protein synthesis the greatest. If a protein has all the 9 essential amino acids than it has an excellent amino acid profile (5,6). 

Another amino acid to look out for if you are wanting to improve muscle mass and strength is arginine. Arginine is an amino acid that is conditionally essential, meaning that it is essential under certain conditions. It is popular among athletes because it is involved in growth and cell-division and promotes muscle protein synthesis (5).

Digestibility is another important factor for proteins. The digestible indispensable amino acid score (PIAAS) is a method for measuring the protein value based on the amino acid requirement of humans and their ability to digest it. Generally, plant based proteins are on the lower end of the DIAAS spectrum compared to that of animal proteins. Once again, to overcome this issue all you need to do is eat a wide-range of foods. Having an abundance of different sources gives your body a better chance to absorb the amino acids from protein. There are a number of plant protein sources that have high digestibility such as rice and hemp (7).

There is no doubt that the vast majority of protein powders available on the market today contain additives such as artificial colours, artificial flavours, and fillers. They are commonly added to help blend in liquids, make the final product palatable or to extend shelf-life. There are hundreds and hundreds of different additives today that as consumers, we need to be aware of. For more information about food additives, check out the Food Standards government page.

The best way to avoid nasty additives is be aware of them, always read the ingredients list, and select raw and organic protein powders. 

Different Types of Plant-Based Protein Powders 

Rice protein is a popular option. A study published in Nutrition Journal found that rice protein consumption post resistance exercise decreases fat-mass and increases lean body mass, skeletal muscle hypertrophy, power and strength comparable to whey protein, the protein source considered to be the gold standard in muscle mass and strength gains. Among many benefits, rice protein has one of the highest DIAAS scores, has a low potential for allergic reactions, high in branched chain amino acids and arginine, and is a good source of vitamins D, E and K.

The downside is that it does not contain all essential amino acids and on it's own, it doesn’t taste all that great.  Blending it with other ingredients helsp mask the taste, or blending with other protein powders (like pea) to form a complete protein (4).

Pea protein is extracted usually from yellow peas. It is not a complete protein, but has a good balanced amino acid profile and is particularly rich in branched chain amino acids. Pea protein is beneficial in that it is cost-effective, allergen-free and raw.

A study was conducted on 161 males, aged 18-35, to assess the effects of pea and whey protein supplementation on muscle thickness and strength after a 12 week resistance training program. The study found that pea protein had comparable results to that of whey and concluded that pea protein can be used as an alternative to whey supplement for athletes. Pea protein is more palatable than rice protein and I would recommend blending the two to form a nice tasting texture and a complete amino acid profile (1).

Hemp protein is arguably the best protein powder for a plant based diet. Hemp protein is extracted from hemp seeds that has been used to treat various disorders for thousands of years in traditional medicine. It has a full 9 essential amino acid profile, is rich in methionine, the amino acid pea protein is lacking, and arginine. Unlike any other plant based protein powders, hemp contains the essential fatty acids omega-3 and omega-6 and is a rich source of fibre and other important vitamins and minerals such as magnesium, potassium and iron. To add to the list, hemp protein is unrefined, raw, easily digestive, easy on the tastebuds  and has no known allergies. The only negative really is that it is generally more expensive when compared to other plant based proteins (2).

Amazonia Raw protein is an excellent choice. The product is raw, very low in sugars, has no synthetic or artificial nutrients and has several different proteins to choose from to meet your individual needs.

If your goal is weight management, Raw Slim & Tone Protein is the product for you. This product is made from a sprouted protein blend and greens, herbs and spices, making it low in fat, carbohydrates and calories. The sugar content is 0.3% from organic stevia (a natural sweetener). Fortified with green powders, 74 different trace minerals and herbs, it's a nutritional powerhouse and tastes delicious too. Available flavours are Cacao Macadamia, Toffee Truffle and Vanilla Cinnamon.

Made up of sprouted fermented pea and fermented wholefoods, the Raw Paleo Fermented Protein is designed to help improve gut health, and for muscle growth and repair. This grain-free protein is also very low in sugar (3%) and has an incredible taste. Salted Caramel all the way!!

The Raw Protein Isolate is my favourite. This is a complete protein source (all 9 essential amino acids are included in this blend), and it's one the whole family can enjoy... Yes, kids too. Containing 53% of the R.D.I for iron, it's a fantastic choice for anyone wanting to bump up their iron levels. Available flavours are Cacao Coconut and Vanilla.

Whatever protein source you opt for, make sure it is from quality source. You and your family deserve it!

~ Written by Stephanie Russell, 3rd Year Nutrition Student. Connect with Steph on @LinkedIn



  1. Babault, N., Paizis, C., Deley G., Guerin-Deremaux, L., Saniez, M., Lefranc-Millot, C., Allaert, F. (2015). Pea proteins oral supplementation promotes muscle thickness gains during resistance training: a double-blind, randomized, Placebo-controlled clinical trial vs. Whey protein. Journal of the International Society of Sports Nutrition, 12(3). 
  2. Callaway, J. (2004). Hempseed as a nutritional resource: An overview. Euphytica, 140, 65-72. 
  3. Nutrient Reference Values for Australia and New Zealand. (2014). Protein. Retrieved from 
  4. Joy, J., Lowery, R., Wilson, J., Purpura, M., De Souza, E., Wilson, S., . . . Jager, R. (2013). The effects of 8 weeks of whey or rice protein supplementation on body composition and exercise performance. Nutrition Journal, 12(18).
  5. Phillips, S. (2016). The impact of protein quality on the promotion of resistance exercise-induced changes in muscle mass. Nutrition & Metabolism13(64).
  6. Roger, D. (2017). Vegan diets: practical advice for athletes and exercisers. Journal of the International Society of Sports Nutrition, 14(3),
  7. Schaafsma, G. (2000). The Protein Digestibility – Corrected Amino Acid Score, The Journal of Nutrition, 130(7), 1865-1867. 
  8. Van Vliet, S., Burd, N., & Van Loon, L. (2015). The Skeletal Muscle Anabolic Response to Plant-versus Animal-Based Protein Consumption. The Journal of Nutrition, 145(9), 2981-1991.