Protein is an essential human nutrient, along with fat and a bunch of minerals and vitamins. Carbohydrate is the non-essential third member of the trio that make up what we call the ‘macronutrients’, protein, fat and carbohydrate. ‘Macro’, because these are the nutrients we need most of and ‘essential’ because they need to be included in our diets as our bodies can’t make them. Most of the vitamins and minerals we need are also essential.
Protein is in fact a chain of amino acids, there are 20 amino acids that our bodies need, mostly to build and maintain our bodies, skin, muscle, bone, hair, nails etc. Nine of these amino acids are essential. So called ‘complete’ proteins are those that contain these nine essential amino acids.
Foods from animals (meat, fish, dairy, eggs) are the best sources of the most complete, easily absorbed proteins. Plant foods (legumes, nuts, grains, vegetables) contain proteins that are incomplete and less easily absorbed. However, a complete suit of the essential amino acids can come from eating combinations of plant protein sources. The bioavailability of proteins from plant sources can be improved through traditional methods like cooking, sprouting or fermentation or through other processes such as freeze drying, irradiation or microwaves.
So most of what your body becomes is made from the protein you eat.
Protein is constantly being broken down and rebuilt as your body renews and maintains itself. There are proteins that make up hair, nails, skin, bones, ligaments, lungs and arteries.
Protein also takes part in many functions in the body including your immune system. It also has a role in the production of neurotransmitters and hormones, including dopamine and serotonin, feel good chemicals. So eating more or less protein can affect your mood.
Your body has various pH values from your blood at pH 7.4 to stomach acid at pH 2. Maintaining these values is critical to health. This is another role of protein.
Protein balances fluids in the body and is critical in the formation of antibodies to fight infection. It also has a role in transporting and storing nutrients.
Amino acids from protein can be used by the body to make glucose, important for supporting high energy demand. When dietary carbohydrates are low, or have been depleted during fasting, glucose can be made from protein.
What does protein consumption mean for our diet
The generally recommended daily intake of protein (RDA) is 0.8 grams/kilo of body weight for healthy persons over the age of 19 years. That’s about 60 grams for an 80 kilogram person, best spread across three meals a day. Although, like most RDAs, this is the minimum below which health will decline. There are no specific RDA recommendations for children, the elderly, those recovering from illness or for athletes.
As a guide, a large egg has around 6 grams of protein, a slice of cheese 7 grams and 100 gram steak has 25 grams of protein.
Beyond the ‘official’ recommendations of 0.8g/kilo of body weight, there are various recommendations and opinions, including the idea that the calculation of the RDA only covers the body building and maintenance roles of protein, not the various other functions as detailed above, so more may be better.
The ‘Protein Leverage Hypothesis’ suggests that we will feel hungry until our daily protein requirements are met. This is suggested as one reason for the obesity epidemic, eating food that is low in protein means we overeat in terms of calories to get the protein we need.
Evidence suggests that eating more protein will result in eating less overall.
Protein is essential for health. We need to get the most complete proteins in their most digestible form.
Prioritising protein could also be good to assist with controlling body weight.
What sustainably FED suggests…
Look for the evidence and what works for your body.
The dietary guidelines for Australians prioritises grain (carbohydrate) foods over protein suggesting that a man 51-70 years old eats 6 servings of grains a day and 2.5 servings of ‘lean’ protein. For a woman of this age range the recommendation is 4 of grains and 2 of protein.
This is interesting given that we know carbohydrate is a non essential nutrient and that protein, quite possibly more protein than the Recommended Daily Allowance, is essential.
Perhaps we need to build sustainable diets around protein as the foundation rather than carbohydrates or kilocalories or a plant focus.
Sustainably FED recognises the need for critical amino acids in diets and the foods that provide these essentials must be present in the diet. This is easy to say but not so easy to deliver across all societies.
Australian Dietary Guidelines – providing the scientific evidence for healthier Australian diets (2013)
Bohrer, Benjamin M. “Review: Nutrient Density and Nutritional Value of Meat Products and Non-Meat Foods High in Protein.” Trends in Food Science & Technology 65 (July 1, 2017): 103–12.
Noakes, M, (2018) Protein Balance: New Concepts for Protein in Weight Management; CSIRO, Australia.
Nilsson, Andreas, Diego Montiel Rojas, and Fawzi Kadi. “Impact of Meeting Different Guidelines for Protein Intake on Muscle Mass and Physical Function in Physically Active Older Women.” Nutrients 10, no. 9 (September 2018): 1156.
Nkhata, Smith G., Emmanuel Ayua, Elijah H. Kamau, and Jean-Bosco Shingiro. “Fermentation and Germination Improve Nutritional Value of Cereals and Legumes through Activation of Endogenous Enzymes.” Food Science & Nutrition 6, no. 8 (2018): 2446–58.
Pribis, Peter. “Protein Intake and Mood: A Systematic Review.” The FASEB Journal 30, no. S1 (2016): 679.10-679.10. https://doi.org/10.1096/fasebj.30.1_supplement.679.10.
Schonfeldt, Hettie, and Nicolette Hall. “Dietary Protein Quality and Malnutrition in Africa.” The British Journal of Nutrition 108 (August 1, 2012): S69–76.