As part of a varied diet, plant-based proteins are nutritionally adequate and have pleiotropic effects that may benefit patients with chronic kidney disease (CKD), according to a new report.
Writing in the Journal of Renal Nutrition, Shivam Joshi, MD, of the New York University Langone Medical Center, and coauthors addressed concerns that persist in the nephrology community that amino acid and protein deficiencies from plant-based diets may result in malnutrition in patients with CKD. Dr Joshi and his colleagues point out that patients with CKD have been shown to consume 0.7–1.2 g/kg/day of mostly plant-based protein without any negative effects.
Directing patients with CKD to consume more animal-based proteins may increase serum phosphorus levels, which can promote CKD progression and worsen secondary hyperparathyroidism.
“Although plant-based foods can contain more phosphorus, they are stored in a nonabsorbable form as phytate,” Dr Joshi and his coauthors wrote. “The phosphorus in plant foods is thought to be only one-third bioavailable because human gut lacks the enzyme phytase, whereas animal-based foods are approximately two-thirds available.”
Patients who replace animal-based proteins with plant-based proteins have experienced reductions in the severity of hyperphosphatemia, hypertension, and metabolic acidosis.
“Nephrologists should not avoid using plant proteins because they are lower in biological value,” Dr Joshi told Renal & Urology News. “Plant proteins, when part of a balanced diet, even if it excludes animal protein, do not cause protein deficiency or harm. In fact, if nephrologists replaced animal proteins with plant proteins, they might do more benefit for the patient by reducing their serum phosphate levels, blood pressure, and levels of metabolic acidosis, not to mention levels of inflammation and problems within the gut microbiome.”
Plant-based diets are generally acid-neutral or base-producing, and thus would protect against acidemia. They also have been shown to be useful in managing and reversing diabetes mellitus by decreasing the amount of refined carbohydrates consumed and promoting long-term weight loss. Studies have shown that plant-based diets can reverse heart disease probably by favorably altering lipids, decreasing inflammation, and reducing atherosclerosis.
“I hope nephrologists have one less reservation with incorporating plant-based diets in the treatment of their patients,” Dr Joshi said. “These diets have pleiotropic effects and have been useful for the treatment of diabetes, obesity, and heart disease, so it’s not unexpected that these diets can be beneficial for patients with CKD. Our desire to ensure adequate protein intake may have sacrificed other important aspects of a patient’s care along the way.”
“This is an excellent and comprehensive review article on the use of plant-based diets in CKD from the nephrologist’s perspective,” Joseph Vassalotti, MD, Chief Medical Officer for the National Kidney Foundation (NKF), told Renal & Urology News. “The review addresses some of the concerns and myths about the risks of vegetarian and vegan diets in CKD, particularly regarding the quantity and quality of protein intake as well as the phosphorus bioavailability.”
Although Dr Vassalotti agrees with the opinions offered by Dr Joshi and his coauthors, he pointed out their paper could also have emphasized the importance of the registered dietitian. “In the US, essentially all dialysis patients are seen by a registered dietitian because of the Medicare conditions of coverage for dialysis facilities,” he said. “An unfortunate statistic is that only about 10% of CKD patients receive medical nutrition therapy with a registered dietitian in the year before the initiation of dialysis. I think we need to do better for our patients to help guide them to overcome fears and misconceptions about diet and moreover to help improve health and patient outcomes.”
Prior studies have associated medical nutrition therapy with slower CKD progression and reduced mortality in the first year of dialysis.
“Overall, dietary questions and concerns about CKD are very common in my experience in caring for patients and fielding questions for the National Kidney Foundation,” Dr Vassalotti said. “Instead of focusing on a magical beneficial food or a deleterious unhealthy one as is often the case in the media or advertisements, an approach that incorporates the patient’s lifestyle to consider healthy dietary patterns is more likely to be successful in my opinion.”
He pointed out that Dr Joshi and coauthors offer the plant-based diet that in the broad perspective is one of several healthy dietary patterns that an individual patient can consider with the clinical team. Other patterns are the Mediterranean, Dietary Approaches to Stop Hypertension (DASH), and Low AGE diet. “These are not really ‘diets’ in the sense of the lay perception of an extreme usually short-term approach to weight loss, but a long-term approach to kidney health,” Dr Vassalotti said. “The best way to individualize the use of one of these healthy eating patterns or modified patterns is with an interdisciplinary approach that includes a nephrologist and a registered dietitian, at minimum, to incorporate the patient’s personal preferences, financial constraints, and medical complications, such as hyperkalemia or heart failure.”
He noted that the NKF’s Kidney Disease Outcomes Quality Initiative (KDOQI) clinical practice guideline on nutrition in CKD is tentatively scheduled to be published in the next calendar year in partnership with the Academy of Nutrition and Dietetics.
Joshi S, Shah S, Kalantar-Zadeh K. Adequacy of plant-based proteins in chronic kidney disease. J Ren Nutr. 2018; published online ahead of print.