Written by Dr Kelly Lambert, Advanced Accredited Practising Dietitian
Interest in high protein diets among the Australian population has been high for several years. Sales of protein powders in Australia exceeded $200 million in 2021 and are forecast to grow more than 7% per annum (1). This interest in high protein eating is partly driven by a perception that extra protein is required to stay healthy and claims that mankind ate this way in palaeolithic times.
Yet most Australians (99%) eat enough protein for good health (2). So is eating extra protein a bad thing ?
Yes ! Extra protein – either from dietary supplements or from food may have detrimental effects on kidney function and long-term health by causing dilation of the afferent arteriole in the kidney and increasing GFR. This can then lead to damage to kidney architecture over time due to glomerular hyperfiltration (3). Individuals with diabetes or those who are obese are at high risk of developing de novo CKD because of excessive protein intake. In those with existing CKD this type of eating can also accelerate progression of existing CKD (4). There are other unwanted side effects from too much protein including an increase in calories and an increase in urea, uric acid and total acid load. Proteins are metabolised in the colon and cause gut dysbiosis when consumed in excessive amounts (5). Animal derived sources of protein also produce Trimethylamine which increases the risk of cardiovascular disease (6).
So what is the take home message ? Enjoy a small (palm sized) portion of protein rich food at your main meal and enjoy a diet with a wide variety of fruit, vegetables, nuts, seeds, wholegrains and dairy products and you will be highly likely to have met your protein needs. If in doubt talk to an Accredited Practicing Dietitian or your Doctor.
Dr Kelly Lambert is an Advanced Accredited Practising Dietitian with qualifications in knowledge translation, health economics and management, and two decades of experience as a renal dietitian and a doctorate investigating health literacy and cognitive impairment in end stage kidney disease. Dr Lambert is the Academic Program Director for the Nutrition and Dietetics Program at the University of Wollongong. Dr Lambert’s research interests are intended to support people with kidney disease to live better lives and to progress the science about developing better patient education materials.