Protein has to be the most researched nutrient when it comes to sports nutrition and exercise, particularly for the bodybuilding scene and for lean muscle gain. However, protein is an important macronutrient across all stages of life and being aware of your consumption is necessary even if you consider yourself far from an elite athlete.
What is protein?
According to the Australian National Health and Medical Research Council, protein occurs in all living cells. Protein is made up of long chains (peptides) of singular units called amino acids. There are approximately 20 amino acids, nine of which are considered essential, meaning that our body cannot synthesise them so we must get them externally through the food in our diet (1).
Amino acids are used for the creation of body proteins and other metabolites, hence why they are often referred to as the building blocks of protein. The proteins of the body are continually broken down and re-synthesised in a process called protein turnover.
Amino acids can also be used as a source of energy. Glucose is the main source of fuel for our brain and central nervous system. If our fuel supply to our brain is low, our body can break down protein from its muscle stores (a process called catabolism) to be converted into glucose as a survival mechanism.
Why does my body need protein?
Protein in the human body has both functional and structural properties including:
- Normal growth and development throughout life stages
- Adequate skeletal, smooth and cardiac muscle for normal functioning of the body and its organs
- Skeletal muscle contraction, growth, recovery and adaptation from physical activity and exercise
- Building joint cartilage, hair, skin and nail cells
- Building other functional and cellular components including hormones, enzymes and antibodies
- Transportation of small molecules within cells and around the body
How does my body digest protein?
The digestion of protein begins in the mouth when we first chew our food. Chewing physically breaks down our food and mixes it with saliva and salivary enzymes, which makes it easier to swallow.
The food bolus travels down our oesophagus to enter our stomach. Protein is mixed with gastric juices and denatured by our stomach acid and another class of enzymes called proteases. This process breaks down protein into its smaller constituents, peptides and amino acids. These microscopic units are further digested with the help of pancreatic enzymes, allowing them to be moved through our small intestine and absorbed via its brush border into our bloodstream for circulation around the body and utilisation in various bodily functions, such as those listed above.
How much protein do I need each day?
It appears that the current protein recommendations for Australian adults underestimate our true requirements for optimal health and muscle mass. The latest scientific research suggests that consumption of 1.2-1.6g of protein per kilogram of body weight per day is an appropriate protein target to assist prevention and treatment of obesity and support our increasing needs as we age (2).
For example, if your current weight is 80kg then your dietary protein requirements are between 96-128g per day.
This recommendation takes into account the general physical activity required for the prevention and treatment of obesity i.e optimising muscle mass, whereas previous recommendations (Australian RDI for protein) of 0.75g/kg/d for women and 0.84g/kg/d for men, did not. Highlighting the need for guidelines and Nutrient Reference Values to be updated.
There are many young adults looking to achieve goals beyond the general prevention and treatment of obesity. These people include many elite athletes and competitive bodybuilders (and those striving towards this level). In this case, the protein recommendations have been suggested at 2.3-3.1g/kg/d to maximise the retention of lean body mass in resistance-trained individuals during hypocaloric periods (low overall energy intake) (3).
It’s important to note that our protein requirements will change at different stages in our lives, including childhood, adolescence, adulthood, pregnancy and elder years. Also, various physical demands impact our protein requirements. We put our bodies through this intentionally in terms of sport, exercise and labour intensive work, or unintentionally, such as times of physical trauma, stress or certain medical conditions. Therefore, we must adapt our intake depending on our individual circumstances and goals.
What foods contain protein?
Protein is found in a variety of foods from animal and plant origins, including:
- All meat and poultry e.g. beef, pork, lamb, duck, chicken, turkey and kangaroo
- Fish and seafood e.g. salmon, tuna, barramundi, prawns, oysters and octopus
- Dairy products like milk, cheese and yoghurt
- Tofu, tempeh and soy
- Beans and legumes e.g. edamame, kidney beans, black beans and lentils
- Some whole grains including brown rice, quinoa and spelt
- Protein alternatives like seitan and nutritional yeast
- Protein powder supplements like whey, casein, brown rice and pea isolate
The protein quantity found within the above foods will vary greatly and even more so between brands. The best way to assess the protein quantity of a product is to read the nutrition information panel located on the packaging. Compare brands by looking at the ‘per 100g’ amount of protein, as serving sizes will differ.
When should I consume protein?
According to CSIRO, after reviewing statistics from the Australian Health Survey, both men and women are consuming most of their protein during their dinner meal, followed closely by lunch and the least amount of protein through our breakfast and snacks (2). This is typical of a Western-style diet when you consider the foods that contain protein.
This pattern of protein consumption is not in line with scientific literature if your goal is to optimise muscle protein synthesis and increase muscle mass combined with resistance training i.e. if you’re going to the gym to get swole! This is where protein distribution is paramount. It is recommended to consume 0.25g-0.3g/kg distributed across the day (across 4-7 meals) (3,4). Considering Australian adults’ protein consumption patterns, you may need to bump up your protein intake to hit your targets at breakfast and snacks, rather than focusing solely on your daily intake.
If you’re not all about the gains, it’s not entirely necessary to be counting the exact amount of protein in your diet. If you are at the beginning of your health and fitness journey or your focus is general wellbeing, simply aim to have a variety of whole foods in your diet with a protein food source at each meal and snack. For example:
Simple meal suggestion
Rolled oats with chia and sunflower seeds, milk and kiwi fruit
Coffee with a handful of mixed nuts
Tinned tuna and cucumber on crackers
Chicken stir-fry with Asian greens and brown rice
Natural yoghurt and mixed berries
Is a high-protein diet dangerous?
Considering the higher end of protein recommendations previously discussed, some may argue this is still too low and may find that they function well with a higher intake. However, a well-conducted systematic review found that protein supplementation beyond total protein intakes of 1.62 g/kg/day resulted in no further resistance exercise training (RET) induced gains in free fat mass. The study proved that an intake of 1.6g/kg/d of protein was sufficient and necessary to optimise RET-induced gains and 1RM strength (5). Another study also looked at a protein intake of 4.4g/kg/d and reported no effect on body composition in resistance-trained individuals who otherwise maintain the same training regimen (6).
It is difficult to define what single amount equates to a high-protein diet and how this might affect a generally healthy adult in the long-term. However, there are some conditions where excessive protein has been associated with risks and this includes pregnancy, previous liver damage or previous kidney damage or impaired functioning, where an individualised approach to nutrition is essential alongside the advice of an appropriate medical professional.
Learn more about protein during pregnancy and breastfeeding here on the True Protein website.
With little conflicting evidence regarding a high protein intake, try thinking about your intake practically. Excessive protein doesn’t appear to be beneficial in terms of strength and muscle gain but intakes above the current dietary guidelines have shown improvements for weight management, fat loss and satiety in addition to muscle gain and increasing strength. So if you’re generally well and these are your goals, then bump up the protein!
Do I need to supplement protein?
This depends on your individual circumstances such as your eating habits, lifestyle, exercise demands, muscle mass, health profile and health and fitness goals.
As protein supplements are well researched, they are generally considered safe to include as part of a healthy diet and fitness routine. The majority of the risks associated with protein powder supplements comes from the addition of other ingredients or contamination during manufacturing, so be sure to purchase from a reputable brand that is transparent with their ingredients.
As protein is found in a wide variety of foods commonly consumed in a Western diet, protein deficiency is rare in Australia. However, we may experience times in our lives when we have a low protein intake and supplementation may be a useful option. These situations can include:
- If you follow a vegetarian or vegan diet, or you don’t eat a lot of meat in general
- Certain illness or medical conditions where your appetite is affected or your nutritional requirements are increased
- During pregnancy and breastfeeding, protein requirements increase and aversion to food can be common
- During dieting, when our energy is restricted, we have an increased need for protein to preserve our muscle mass
- As we age our body requires more protein to compensate for age-related changes in protein metabolism and increasing skeletal muscle loss, known as sarcopenia (7)
Aside from using protein powder across various life stages, protein as a sports supplement is common practice.
According to the Australian Bureau of Statistics, almost two in three Australian adults are overweight or obese, and in 2011-12, over 2.3 million Australians reported that they were on a diet to lose weight or for some other health reason. As the benefits/needs of protein have already been discussed, it’s clear that a protein supplement is the cornerstone of a well-designed supplement regimen to support your health and fitness journey.
What are the different types of protein supplements available?
The most common type of protein powder supplement is in the form of whey, a natural component of dairy milk, and this includes whey protein isolate and concentrate. There are other protein powders from animal origins including casein, collagen and hydrolysed whey.
Plant-based options include derivatives from soy, pea, rice and various other vegetables. It’s important to note that the amino acid profile is not entirely complete with some forms of plant-based protein powders. True Vegan85 is a blend of pea protein isolate and organic brown rice protein, a combination that ensures a complete amino acid profile.
- National Research Council (US) Subcommittee on the Tenth Edition of the Recommended Dietary Allowances. Recommended Dietary Allowances: 10th Edition. Washington (DC): National Academies Press (US); 1989. 6, Protein and Amino Acids. Available from: https://www.ncbi.nlm.nih.gov/books/NBK234922/
- Noakes, M, (2018) Protein Balance: New Concepts for Protein in Weight Management; CSIRO, Australia.
- Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition. 2017;14:20. doi:10.1186/s12970-017-0177-8.
- Mamerow MM, Mettler JA, English KL, et al. Dietary Protein Distribution Positively Influences 24-h Muscle Protein Synthesis in Healthy Adults. The Journal of Nutrition. 2014;144(6):876-880. doi:10.3945/jn.113.185280.
- Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. Published Online First: 11 July 2017. doi: 10.1136/bjsports-2017-097608.
- Antonio J, Peacock CA, Ellerbroek A, Fromhoff B, Silver T. The effects of consuming a high protein diet (4.4 g/kg/d) on body composition in resistance-trained individuals. Journal of the International Society of Sports Nutrition. 2014;11:19. doi:10.1186/1550-2783-11-19.
- Bauer, Jürgen et al. Evidence-Based Recommendations for Optimal Dietary Protein Intake in Older People: A Position Paper From the PROT-AGE Study Group. Journal of the American Medical Directors Association , Volume 14 , Issue 8 , 542 - 559.