by Even athletes with intense training regimens can usually meet all of their protein needs without supplementation. Photo / Getty Images
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As well as Jennifer Bowden’s columns in the Listener NZ and here at listener.co.nz, subscribers can access her “Debunking Myths” column, in which she explores food and nutrition myths. This week,
she investigates the truth about protein.
In the world of nutrition, protein often takes the spotlight as the hero of the diet. It’s touted for everything from building muscle to boosting energy. But is more protein always better, or are we overestimating its benefits? Research suggests that there is more to content than the marketing slogans promise.
Protein, fat, and carbohydrates are vital nutritional macronutrients that our body requires. Protein is used for energy and as a building block in many complex molecules that fulfill different roles.
These include functional roles, such as digestive enzymes, oxygen transport in the blood, immune system antibodies, and structural roles in our muscles. The body of an average 70kg adult contains around 11kg of protein, of which around half is skeletal muscle.
In New Zealand, the recommended dietary intake (RDI) of protein for adults is 52g per day for men and 37g for women. That increases for people aged 70 and over to 65g for men and 46g for women each day, due to their higher protein maintenance needs.
The typical Western diet provides enough protein for most adults, and only 2% of New Zealand adults eat inadequate levels of protein, according to the NZ Adult Nutrition Survey 2008/09. However, people over the age of 70 did not do so well, with 13%-16% not meeting their higher protein needs.
Athletes also often have elevated needs as their protein needs for fuel and muscle maintenance increase with training intensity and duration. Some athletes take protein supplements for specific reasons, noted a 2019 review in Nutrients. For example, branched-chain amino acid supplements, studies have suggested, may improve training performance and reduce post-training muscle soreness.
However, according to the Australian Institute of Sport, even athletes with rigorous training regimes can meet all their protein needs without supplementation.
Interestingly, gym goers and non-professional sportsmen consume protein and amino acid-based supplements in addition to a protein-rich diet, even though their workload does not usually meet the levels of athletes. Their physical activity levels generally fall within the recommended protein RDI limits for the general population. But they still choose to supplement more protein unnecessarily.
High protein diets result in more undigested protein passing through the stomach into the large intestine, where it is fermented and the gut microbiota changes. One clinical trial found that a high-protein diet increased the production of hazardous metabolites and decreased the production of cancer-protective metabolites in the colon, which increased the long-term risk of colon disease. Concerns have also been raised about high protein diets having a negative impact on bone health and kidney function. They are definitely harmful to those who already have kidney dysfunction.
Moreover, nutritional supplements, including protein-based ones, are often contaminated with prohibited substances such as compounds and anabolic hormones such as steroids, noted in article 2023 in Limits in Sport and Active Living. A 2008 review found that about 15% of supplements were contaminated with anabolic steroids or other banned substances, and a 2017 review found that between 12% and 58% were contaminated.
In fact, a 2022 Consumer New Zealand investigation found that six sports supplements sold in New Zealand contained illegal drugs – including stimulants like amphetamine and medications used to treat ADHD and Parkinson’s disease .
Most athletes rely on expert guidance to manage their protein intake, avoiding the risks of accidental doping or unnecessary protein over-intake. Many consumers would benefit from a similar approach, as a well-balanced diet usually provides enough protein. Both animal and plant foods contain protein, so a varied diet ensures you get enough.
For the general population, including gym goers and weekend athletes, incorporating a small portion of protein-rich foods such as meat, poultry, fish, legumes, eggs, nuts and seeds into 3-5 daily meals or snacks serves your protein needs. . Other foods such as milk, cheese, yoghurt, whole grains, vegetables and fruit also contain protein, which adds to the overall intake.
By focusing on a varied and balanced diet you can easily maintain optimal protein levels for a healthy lifestyle, rather than focusing specifically on protein and following the misguided belief that “more is always better”.
