Is Dietary Red Meat Kidney Toxic?

Egg Intake in Chronic Kidney Disease

Patients with chronic kidney disease (CKD) are often instructed to adhere to a renal-specific diet depending on the severity and stage of their kidney disease. The prescribed diet may limit certain nutrients, such as phosphorus and potassium, or encourage the consumption of others, such as high biological value (HBV) proteins. Eggs are an inexpensive, easily available and high-quality source of protein, as well as a rich source of leucine, an essential amino acid that plays a role in muscle protein synthesis. However, egg yolk is a concentrated source of both phosphorus and the trimethylamine N-oxide precursor, choline, both of which may have potentially harmful effects in CKD. The yolk is also an abundant source of cholesterol which has been extensively studied for its effects on lipoprotein cholesterol and the risk of cardiovascular disease. Efforts to reduce dietary cholesterol to manage dyslipidemia in dialysis patients (already following a renal diet) have not been shown to offer additional benefit. There is a paucity of data regarding the impact of egg consumption on lipid profiles of CKD patients. Additionally, egg consumption has not been associated with the risk of developing CKD based on epidemiological studies. The egg yolk also contains bioactive compounds, including lutein, zeaxanthin, and vitamin D, which may confer health benefits in CKD patients. Here we review research on egg intake and CKD, discuss both potential contraindications and favorable effects of egg consumption, and describe the need for further research examining egg intake and outcomes in the CKD and end-stage renal disease population.

Novel treatment strategies for chronic kidney disease: insights from the animal kingdom

Many of the >2 million animal species that inhabit Earth have developed survival mechanisms that aid in the prevention of obesity, kidney disease, starvation, dehydration and vascular ageing; however, some animals remain susceptible to these complications. Domestic and captive wild felids, for example, show susceptibility to chronic kidney disease (CKD), potentially linked to the high protein intake of these animals. By contrast, naked mole rats are a model of longevity and are protected from extreme environmental conditions through mechanisms that provide resistance to oxidative stress. Biomimetic studies suggest that the transcription factor nuclear factor erythroid 2-related factor 2 (NRF2) offers protection in extreme environmental conditions and promotes longevity in the animal kingdom. Similarly, during months of fasting, immobilization and anuria, hibernating bears are protected from muscle wasting, azotaemia, thrombotic complications, organ damage and osteoporosis - features that are often associated with CKD. Improved understanding of the susceptibility and protective mechanisms of these animals and others could provide insights into novel strategies to prevent and treat several human diseases, such as CKD and ageing-associated complications. An integrated collaboration between nephrologists and experts from other fields, such as veterinarians, zoologists, biologists, anthropologists and ecologists, could introduce a novel approach for improving human health and help nephrologists to find novel treatment strategies for CKD.

Long-Term Effects of High-Protein Diets on Renal Function

Chronic kidney disease (CKD) has a prevalence of approximately 13% and is most frequently caused by diabetes and hypertension. In population studies, CKD etiology is often uncertain. Some experimental and observational human studies have suggested that high-protein intake may increase CKD progression and even cause CKD in healthy people. The protein source may be important. Daily red meat consumption over years may increase CKD risk, whereas white meat and dairy proteins appear to have no such effect, and fruit and vegetable proteins may be renal protective. Few randomized trials exist with an observation time greater than 6 months, and most of these were conducted in patients with preexisting diseases that dispose to CKD. Results conflict and do not allow any conclusion about kidney-damaging effects of long-term, high-protein intake. Until additional data become available, present knowledge seems to substantiate a concern. Screening for CKD should be considered before and during long-term, high-protein intake.