In recent years, a growing body of evidence has emerged on the benefits of plant-based diets for the prevention and treatment of lifestyle diseases. In parallel, data now exist regarding the treatment of chronic kidney disease and its most common complications with this dietary pattern. Improving the nutrient quality of foods consumed by patients by including a higher proportion of plant-based foods while reducing total and animal protein intake may reduce the need for or complement nephroprotective medications, improve kidney disease complications, and perhaps favorably affect disease progression and patient survival. In this In Practice article, we review the available evidence on plant-dominant fiber-rich diet as it relates to kidney disease prevention, chronic kidney disease incidence and progression, metabolic acidosis, hyperphosphatemia, hypertension, uremic toxins, need for kidney replacement therapy including dialysis, patient satisfaction and quality of life, and mortality. Further, concerns of hyperkalemia and protein inadequacy, which are often associated with plant-based diets, are also reviewed in the context of available evidence. It is likely that the risks for both issues may not have been as significant as previously thought, while the advantages are vast. In conclusion, the risk to benefit ratio of plant-based diets appears to be tilting in favor of their more prevalent use.

Concerns regarding protein and amino acid deficiencies with plant-based proteins have precluded their use in chronic kidney disease (CKD) patients. Many of these concerns were debunked years ago, but recommendations persist regarding the use of "high-biological value" (animal-based) proteins in CKD patients, which may contribute to worsening of other parameters such as blood pressure, metabolic acidosis, and hyperphosphatemia. Plant-based proteins are sufficient in meeting both quantity and quality requirements. Those eating primarily plant-based diets have been observed to consume approximately 1.0 g/kg/day of protein, or more. CKD patients have been seen to consume 0.7-0.9 g/kg/day of mostly plant-based protein without any negative effects. Furthermore, those substituting animal-based proteins for plant-based proteins have shown reductions in severity of hypertension, hyperphosphatemia, and metabolic acidosis. Plant-based proteins, when consumed in a varied diet, are not only nutritionally adequate but have pleiotropic effects which may favor their use in CKD patients.

Purpose of review

Plant-based diets have been used with growing popularity for the treatment of a wide range of lifestyle-related diseases, including diabetes, hypertension, and obesity. With the reinvigoration of the dietary management of chronic kidney disease (CKD) and the use of low protein diets for secondary prevention of CKD to delay or prevent dialysis therapy, there is an increasing interest in the potential role of plant-based diets for these patients.

Recent findings

Recently, a body of evidence related to the role of plant-based diets in preventing CKD has reemerged. Several observational studies have shown that red and processed meat have been associated with increased risk of CKD as well as faster progression in those with preexisting CKD. In several substitution analyses, replacement of one serving of red and/or processed meat has been linked with sizable reductions in CKD risk. Although limited, experimental trials for the treatment of metabolic acidosis in CKD with fruits and vegetables show outcomes comparable to oral bicarbonate. The use of plant-based diets in CKD may have other benefits in the areas of hypertension, weight, hyperphosphatemia, reductions in hyperfiltration, and, possibly, mortality. The risk of potassium overload from plant-based diets appears overstated, mostly opinion-based, and not supported by the evidence. Plant-based diets are generally well tolerated and provide adequate protein intake, including essential amino acids as long as the diet is correctly implemented.

Summary

Plant-based diets should be recommended for both primary and secondary prevention of CKD. Concerns of hyperkalemia and protein inadequacy related to plant-based diets may be outdated and unsupported by the current body of literature. Healthcare providers in general medicine and nephrology can consider plant-based diets as an important tool for prevention and management of CKD.

Background

Plant-based diets are defined as an eating pattern focused on the consumption of unprocessed fruits, vegetables, nuts, whole grains, oils, and beans. They can include various forms of vegetarian, vegan, DASH, and Mediterranean diets. Plant-based diets have proven useful in the prevention and treatment of several lifestyle diseases like type 2 diabetes, hypertension, and obesity. Recently, a growing body of literature has emerged regarding plant-based diets for patients with kidney failure, including those on dialysis. Although evidence is still limited, preliminary findings are encouraging.

Summary

This article reviews current literature on the use of plant-based diets in the treatment of patients on dialysis.

Traditionally, diets for kidney disease were low in potassium. This recommendation was based on outdated research and often wrong assumptions that do not reflect current evidence. In fact, studies conducted over the past decades show patients with CKD, including kidney failure, do not benefit from the restriction of plant foods relative to control. Generally, dietary potassium does not correlate with serum potassium, and we posit that this is due to the effects of fiber on colonic potassium absorption, the alkalinizing effect of fruits and vegetables on metabolic acidosis, and the bioavailability of dietary potassium in plant foods. Also, consumption of plant foods may provide pleiotropic benefits to patients with CKD. Emerging dietary recommendations for kidney health should be devoid of dietary potassium restrictions from plant foods so that patient-centered kidney recipes can be encouraged and promoted.

Although high-protein diets continue to be popular for weight loss and type 2 diabetes, evidence suggests that worsening renal function may occur in individuals with-and perhaps without-impaired kidney function. High dietary protein intake can cause intraglomerular hypertension, which may result in kidney hyperfiltration, glomerular injury, and proteinuria. It is possible that long-term high protein intake may lead to de novo CKD. The quality of dietary protein may also play a role in kidney health. Compared with protein from plant sources, animal protein has been associated with an increased risk of ESKD in several observational studies, including the Singapore Chinese Health Study. Potential mediators of kidney damage from animal protein include dietary acid load, phosphate content, gut microbiome dysbiosis, and resultant inflammation. In light of such findings, adopting current dietary approaches that include a high proportion of protein for weight reduction or glycemic control should be considered with care in those at high risk for kidney disease. Given the possibility of residual confounding within some observational studies and the conflicting evidence from previous trials, long-term studies including those with large sample sizes are warranted to better ascertain the effects of high protein intake on kidney health.

Purpose of review

Nearly half of all Americans with chronic kidney disease (CKD) also have type-2-diabetes (T2D). Whereas traditional and emerging pharmacotherapies are increasingly frequently used for the management of CKD in diabetes (CKD/DM), the role of integrated or multimodal interventions including the potentially synergistic and additive effect of diet and lifestyle modifications in addition to pharmacotherapy has not been well examined, in sharp contrast to the well-known integrated approaches to heart disease.

Recent findings

Low-carbohydrate low-fat diets are often recommended in T2D, whereas low-protein diets (LPD) are recommended by guidelines for nondiabetic CKD with increasing emphasis on plant-based protein sources. High-protein diets with greater animal protein lead to glomerular hyperfiltration, especially in patients with T2D, and faster decline in renal function. Guidelines provide differing recommendations regarding the amount (low vs high) and source (plant vs animal) of dietary protein intake (DPI) in CKD/DM. Some such as KDIGO recommend 0.8 g/kg/day based on insufficient evidence for DPI restriction in CKD/DM, whereas KDOQI and ISRNM recommend a DPI of 0.6 to <0.8 g/kg/day. A patient-centered plant-focused LPD for the nutritional management of CKD/DM (PLAFOND), a type of PLADO diet comprising DPI of 0.6 to <0.8 g/kg/day with >50% plant-based sources, high dietary fiber, low glycemic index, and 25-35 Cal/kg/day energy, can be implemented by renal dietitians under Medical Nutrition Therapy.

Summary

Potential risks vs benefits of high vs low protein intake in CKD/DM is unknown, for which expert recommendations remain opinion based. Randomized controlled studies are needed to examine safety, acceptability and efficacy of PLAFOND.

Emerging research suggests that a more liberalized diet, specifically a more plant-based diet resulting in liberalization of potassium intake, for people receiving hemodialysis is necessary and the benefits outweigh previously thought risks. If the prescribed hemodialysis diet is to be liberalized, the need to illuminate and prevent potential pitfalls of a liberalized potassium diet is warranted. This paper explores such topics as partial to full adherence to a liberalized diet and its consequences if any, the advantages of a high-fiber intake, the theoretical risk of anemia when consuming a more plant-dominant diet, the potential benefits against renal acid load and effect on metabolic acidosis with increased fruit and vegetable intake, the putative change in serum potassium levels, carbohydrate quality, and the healthfulness of meat substitutes. The benefits of a more plant-based diet for the hemodialysis population are multifold; however, the possible pitfalls of this type of diet must be reviewed and addressed upon meal planning in order to be avoided.