In a Korean community-based prospective study, higher intake of protein was associated with RHF and rapid decline of eGFR compared to lower protein intake in healthy adults. These findings suggest that a high protein diet can have deleterious effects on kidney function in the general population.

Discussion

In the same journal the results of a study on dietary protein intake and kidney function decline in stable patients after myocardial infarction (MI) was reported: Dietary protein intake and kidney function decline after myocardial infarction: the Alpha Omega Cohort Esmeijer K et al Nephrol Dial Transplant 2019. Post-MI patients have an increased annual risk of kidney function decline (double compared to general population), and are therefore at risk of CKD. Although KDIGO guidelines recommend to limit daily total protein intake in adults at risk for CKD [16,17], it is unknown whether protein restriction in post-MI patients slows down kidney function decline. The Alpha Omega Cohort was used, a prospective cohort of Dutch patients aged 60-80 years with a diagnosis of MI, 10 years before study entry. Data on food intake was collected using a 203-item food frequency questionnaire (FFQ) at baseline. Using data of 2255 patients with a follow-up of 41 months, the authors found a strong linear association between protein intake and annual kidney function decline. Annual change in eGFR-cysC was double in patients with protein intake >1.20 compared with those taking proteins <0.80 g/kg for ideal body weight: -1.60 vs -0.84 mL/min/1.73 m². These was also an inverse association between intake of animal protein and eGFR-cysC and a similar but non-significant association for plant protein intake. This study showed that higher protein intake was associated with a more rapid kidney function decline in post-MI patients.

In their editorial comment [18], the authors write that a high-protein diet (HPD) is not a emerging food culture but rather a prevailing dogma in society. ‘It has even gone so far that we feel pressured to eat more proteins and less carbohydrates’, the authors state. They explain how overnutrition has resulted in the acceptance of benefits of a HPD. But, they question: ‘is HPD safe for kidney health or not?’ and list some of the evidence and recommendations against a HPD. Low-protein diet (LPD) is recommended for those with CKD or at risk for CKD, such as diabetes patients and obese subjects with microalbuminuria, and those with reduced kidney reserve (solitary kidney or earlier stages of CKD). The Recommended Dietary Allowance (RDA) for protein is 0.8 g/kg/day and the estimated requirement is likely even lower, around 0.6 g/kg/day. An LPD for CKD management is defined as daily protein in the range of 0.6–0.8 g/kg/day and for persons with a solitary kidney or at high risk of CKD, high protein intake >1.0 g/kg/day should be avoided. They end by writing: ‘It is time to unleash the taboo and make it loud and clear that a high-protein diet is not as safe as claimed, as it may compromise kidney health and result in a more rapid kidney function decline in individuals or populations at high risk of CKD. It is prudent to avoid recommending high-protein intake for weight loss in obese or diabetic patients or those with prior cardiovascular events or a solitary kidney if kidney health cannot be adequately protected.’

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Would you advice patients against a high-protein diet?

• Yes, all patients
• Yes, but only CKD patients or those with increased risk of renal failure
• No