Researchers at the University of Pretoria have made a critical discovery regarding how much protein is in our food. Whether you’re a gym fiend or just someone who cares about your health, here’s what the researchers found out about our friend protein and why it could transform our health and even that of our economy.
Pretoria, South Africa (28 March 2025) – If there’s one word everyone identifying as a gym bro or bunny has etched into their brains, it’s protein.
Now, if you haven’t set foot in a gym in a while or consider a brisk walk heavy-duty exercise, you’d be forgiven for thinking that being overly concerned about protein only applies to people obsessed with putting on muscle. If you don’t want to look like a bodybuilder, is protein really so important?
The short answer is yes. Our bodies need it regardless of whether we’re entering a bodybuilding competition or just trying to meet basic health standards. However, how much protein you need is another matter. Even more interesting is knowing how much protein we’re actually getting from food sources!
You know you need protein, but how much are you actually getting?
Researchers at the Department of Animal Science and School of Health Systems and Public Health at the University of Pretoria made a pretty crucial discovery regarding the methods used to measure the protein content of foods.
They’ve confirmed that current methods often produce inaccurate results. Ie, what the back of the package tells us is usually an estimate.
The exciting part, though, is that this means there’s room for more accurate results. This could go a long way across many factors like preventing malnutrition, encouraging the cultivation of plant-sourced protein that more people can afford, and, of course, helping gym warriors meet their goals. It could even boost the economy if, say, a certain crop is actually more jam-packed with protein than we realise!
How is protein measured?
“Traditionally, scientists have used a method called the ‘proximate system’ to measure protein content,” explains Dr Beulah Pretorius. “By using specific nitrogen-to-protein conversion factors – also called the Jones conversion method – protein content is calculated based on the amount of nitrogen present in foodstuffs. This method assumes that most of the nitrogen in food comes from amino acids (the building blocks of protein) and that a significant portion of those amino acids are part of the protein.”
The commonly used conversion factor is 6.25, which again assumes that all proteins contain about 16% nitrogen. However, the research shows that this method can over- or underestimate the true content present in foodstuffs, ultimately providing inaccurate results.
“This is why scientists prefer to report protein in food composition tables, and to indicate ‘true protein’ on product labels as the sum of individual amino acid residues,” Dr Pretorius says. “The chemical analysis to determine the amino acid content is, however, complicated and costly, and therefore not a feasible methodology to use in developing countries.”
What if we could update and improve the conversion factors that are being used?
In an exploratory study, data was collected on the amino acid content in foods from animal sources. The crude protein was calculated by using the nitrogen value of the samples (as determined by the Kjeldahl method for dairy samples and the Dumas method for meat samples). These were then multiplied by the respective Jones conversion factors of 6.25 for meat samples and 6.38 for dairy samples. True protein was calculated as the sum of amino acid residues (the molecular weight of each amino acid, less the molecular weight of water).
“The findings were concerning,” Professor Hettie Schönfeldt says. “For all animal products, the protein content was over-reported. It became evident that the ‘assumed’ nitrogen content of protein is not 16% but varies significantly depending on the source of protein. By accurately determining protein content, we could not only counter malnutrition but also encourage the cultivation of a diverse range of plant species, including often- overlooked valuable sources of protein. A greater variety of crops would also result in much-desired biodiversity in regions.”
Socio-economic opportunities
“These changes will affect virtually all sectors in the food chain: agriculture, manufacturing, food preservation, labelling and regulatory compliance, to name a few,” Dr Pretorius adds.
To this point, it’s worth noting that the knock-off effect goes well beyond the industry. Healthier children can mean better results in school, better opportunities when they graduate and better futures because of it. It also means that there is room to boost other food types that could be grown by local communities, in turn boosting local economies.
“However, the greatest challenge would probably be to gain acceptance of new food options from the general population,” shares Dr Pretorius. “Humans are by nature resistant to change. It would therefore require intensive, persuasive education to alter dietary preferences.”
Why does protein matter anyway?
Without protein, humans face a plethora of problems, from losing muscle mass to being unable to concentrate. In severe cases, diseases like kwashiorkor or marasmus can develop.
It’s recommended that adults consume around 0/83g per of protein for each kilogram of body weight (per day). Needless to say, protein plays a big role in all our lives, whether we know it or not.
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