Protein does more than build big muscles — it’s essential. Dietitian Olivia Bates explains.
Protein is one of three macronutrients that makes up the food we eat, and one of the key nutrients we all need to maintain a healthy body. It’s involved in building and repairing muscle tissue and supporting our immune systems. From our organs, muscles and brain cells to our skin, hair and nails, every part of us is made up of protein.
While there’s no doubt that protein is a crucial element of anyone’s diet, the quality, quantity and source of protein continues to remain a topic of much debate.
What are proteins made of?
Proteins are composed of smaller chains of chemical compounds called amino acids. There are 20 different amino acids, which can then be separated into two categories: essential and non-essential.
While all amino acids are necessary for our bodies to function, nine essential amino acids must be consumed through diet — this is where protein comes in. The other 11 non-essential amino acids can be produced by our own cells when nourished correctly.
Why is it important?
No matter what your age or your activity level, we all need to consume protein daily for optimal health. The protein we eat is broken down into its amino acids and used by our body for three processes: the creation of new proteins, as a component of other substances such as enzymes and hormones and as an energy source.
Protein and training
Protein has a special role when it comes to exercise — and it’s not just for bodybuilders and pro athletes. Any form of training will have an impact on protein requirements.
Training and exercise cause microscopic tears in muscle fibres. These micro-tears are how muscles are ultimately able to grow. The body uses the amino acids it gets from the protein in our diet to repair and grow these muscle fibres, a process known as anabolism. Each time it does this, it reinforces the strength of the muscle to prevent future damage. This reinforcing allows us to increase the load we can work out with before a micro-tear will occur.
A lack of dietary protein and sleep (an anabolic state in which muscle growth and repair occurs) prevents muscles from being repaired. If these micro-tears continue to occur without being repaired, the muscles will shrink, known as dystrophy.
How much should you eat?
When we talk about how much protein we should eat, it’s often described in terms of grams of protein per kilogram of bodyweight. All these values are based on averages and should be taken as a guide, depending on your personal needs.
The current nutrient reference values for people aged 19-70 is 0.84g/kg for men and 0.75g/kg for women. For your “average” 70kg man, that would be around 59g protein per day, while the same sized woman would require around 53g.
A second method of determining how much protein you need is by using the acceptable macronutrient distribution range (AMDR), which provides guidelines for macronutrients as a percentage of total energy consumption, since carbs, protein and fat all contribute to total energy intake. The current values in Australia are carbohydrates (45%-65% of energy), protein (15%-25% of energy) and fat (20%-35% of energy with limited saturated and trans fats).
These recommendations are based on the most current 2006 guidelines, which reflect the majority of the healthy population. However, for bodybuilders and athletes your values will be higher.
Protein and ageing
When it comes to ageing, protein can play a significant role in maintaining quality of life. Even in the absence of disease, ageing comes with a gradual loss of muscle mass, at a reported rate of 3-8% per decade, which begins to occur in your 40s and 50s.
The role of protein in healthy ageing was a key discussion point at the latest Protein Summit 2.0, where over 60 scientists examined the impact of high quality protein consumption on optimal health and ageing. Both the summit and subsequent research has suggested that protein intake of 1-1.5g/kg of bodyweight may have greater healthy benefits than those offered by current recommendations of about 0.8g/kg.
The amount of protein per meal was also recently flagged as worthy of research. A 2014 study looked at changes in the production of proteins in the body based on an even or uneven protein distribution — whether you have more protein with one meal and less with another. The results showed protein production was 25% higher when the same quantity of protein (about 25-30g/meal) was eaten with breakfast, lunch and dinner compared with less protein in the morning and more in the evening.
This recent research presents the new age thinking regarding protein for older adults, placing specific focus on quantity, quality and timing of protein consumption.
While most people immediately think of meat when they hear the word protein, many are now switching to a plant-based diet, and we’re hearing a whole lot more about plant proteins. But what’s the difference?
It all comes down to their amino acids. Animal proteins are the most similar to human proteins and contain all of the essential amino acids, making them a “complete protein”, while plant proteins generally lack at least one essential amino acid. You may hear people talking about combining two or more plant protein sources as a means of balancing out missing amino acids, but by consuming a wide variety of plant-based proteins over the course of the day, you’re unlikely to miss out on any of the amino acids.
Quinoa, amaranth and chia are all complete proteins, as well as the new kid on the block, hemp, which has been popping up more often since being legalised for consumption in Australia in November last year. As more and more people opt for a plant-based lifestyle, these complete plant proteins have achieved “superfood” status.
What about protein supplements?
Protein powders, shakes, bars and everything in between have become mainstream, especially in the fitness industry. For most people, a balanced diet will ensure they hit their protein requirements, but heavy trainers aiming for consumption levels as high as 3-4g of protein per kilogram of bodyweight are often unable to physically consume the amount of food required, so a supplement is a convenient alternative.
The major benefit of supplements is that they provide an optimum amino acid composition at a much higher rate per gram than natural sources, in a convenient to consume form. If you visit your local health food store or chemist, you’ll find hundreds of different options. If you’re looking for a protein supplement, what you choose will depend on the source of the protein, be it animal such as whey or casein or a plant-based option such as soy, hemp, pea or rice, to name a few. It also comes down to personal preference such as liquid or bar, flavours varieties and use of sweeteners and other extra ingredients.
Are there benefits of a high protein diet?
Over the years we’ve seen the rise (and sometimes the fall) of the Atkins Diet, the South Beach Diet, the Dukan Diet, the Paleo Diet and, most recently, the Keto Diet, to name a few. All these diets focus on a high intake of animal proteins and a low intake of carbohydrates, while the intake of fat varies from one to the other.
Like many diets, these eating plans usually encourage the consumption of plenty of vegetables and avoidance of high-energy, nutrient-poor refined foods — both great eating habits for everyone to adopt as part of a healthy lifestyle.
On the other hand, these diets involve cutting out whole food groups, ultimately limiting access to certain nutrients.
A key criticism of these diets is the high saturated fat content, which tends to accompany high protein diets. High saturated fat is associated with an increased risk of heart disease and many unwanted side effects.
Despite this, there are definitely proven benefits of adopting a high protein diet, but these benefits can also be achieved by consuming a balanced, healthy diet. Regardless of how you eat, protein should be obtained from many sources to ensure you receive all your necessary nutrients, and to achieve optimum health.