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Clinical e-News Blog - June

Written by Dr Kelly Lambert, Advanced Accredited Practising Dietitian

Do high protein diets cause kidney damage?

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.

About the author

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.

References:

  1. Reportlinker.com. Market Report. Australia Protein Supplement Market, By Product Type, By Raw Material, By Application, By Distribution Channel, By Region, Competition Forecast & Opportunity, 2027 2022 [15/5/2022]. Available from: https://www.reportlinker.com/p... Bureau of Statistics. Australian Health Survey: Nutrition First Results - Foods and Nutrients 2014 [6 July 2021]. Available from: https://www.abs.gov.au/statist... G-J, Rhee CM, Kalantar-Zadeh K, Joshi S. The Effects of High-Protein Diets on Kidney Health and Longevity. J Am Soc Nephrol. 2020;31(8):1667-79. doi: 10.1681/asn.2020010028.
  2. Kalantar-Zadeh K, Kramer HM, Fouque D. High-protein diet is bad for kidney health: unleashing the taboo. Nephrology Dialysis Transplantation. 2019. doi: 10.1093/ndt/gfz216.
  3. Cai J, Chen Z, Wu W, Lin Q, Liang Y. High animal protein diet and gut microbiota in human health. Crit Rev Food Sci Nutr. 2021:1-13. doi: 10.1080/10408398.2021.1898336.
  4. Koeth RA, Wang Z, Levison BS, Buffa JA, Org E, Sheehy BT, et al. Intestinal microbiota metabolism of l-carnitine, a nutrient in red meat, promotes atherosclerosis. Nat Med. 2013;19(5):576-85. doi: 10.1038/nm.3145.
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