Red meat intake in chronic kidney disease patients: Two sides of the coin

Highlights

• Red meat is a valuable source of essential amino acids and micronutrients for patients with chronic kidney disease (CKD).

• Red meat intake may lead to elevated production of uremic toxins and increased cardiovascular risk.

• High red meat intake is associated with increased risk for progression of CKD.

• Red meat intake should be limited in patients with CKD.

Abstract

Red meat is an important dietary source of high biological value protein and micronutrients such as vitamins, iron, and zinc that exert many beneficial functions. However, high consumption of animal protein sources, especially red meat, results in an increased intake of saturated fat, cholesterol, iron, and salt, as well as an excessive acid load. Red meat intake may lead to an elevated production of uremic toxins by the gut microbiota, such as trimethylamine n-oxide (TMAO), indoxyl sulfate, and p-cresyl sulfate. These uremic toxins are associated with increased risk for cardiovascular (CV) mortality. Limiting the intake of red meat in patients with chronic kidney disease (CKD) thus may be a good strategy to reduce CV risk, and may slow the progression of kidney disease. In the present review, we discuss the role of red meat in the diet of patients with CKD. Additionally, we report on a pilot study that focused on the effect of a low-protein diet on TMAO plasma levels in nondialysis CKD patients.

Introduction

Patients with chronic kidney disease (CKD) have a high risk for cardiovascular diseases (CVD) due to accelerated arterio- and atherosclerosis [1], [2]. Several cardiovascular (CV) risk factors for CKD have been established in the literature [3], such as hypertension, dyslipidemia, diabetes, oxidative stress, and inflammation. Recently, the accumulation of uremic toxins caused by the imbalance in the composition of gut microbiota has been studied as another potential CV risk factor for patients with CKD [4], [5]. Some of these toxins are generated from metabolites of amino acid breakdown by gut microbiota, such as degradation products of choline and l-carnitine (present in animal protein, such as red meat, and eggs). Accordingly, high consumption of animal protein sources, especially red meat, increases the production of several uremic toxins, including trimethylamine n-oxide (TMAO), indoxyl sulfate (IS), indole-3-acetic acid (IAA), and p-cresyl sulfate (p-CS) [6]. Increased intake of red meat may contribute to high intake of saturated fat, cholesterol, iron, and salt, as well as a high acid load [7]. Taken together, increased intake of red meat could be an important CVD risk factor for patients with CKD.

Researchers have shown that red meat intake may increase the risk for CVD as well as metabolic syndrome, type 2 diabetes, diverticulitis, and cancer, leading to a negative perception of the role of high intake of red meat for health [8], [9], [10], [11], [12], [13]. Moreover, high protein intake via meat seems to accelerate progression of kidney failure [14]. Because high protein intake promotes glomerular hyperfiltration in animal models, a restriction of total dietary protein intake should slow the progression of nephropathy [15]. On the other hand, red meat has high nutritional value, provides all the essential amino acids, and is the best source of vitamin B₁₂, heme iron, and zinc. It is likely that the change in diet that occurred millions of years ago—from fruits and plants to increasing quantities of wild game meat that are rich in polyunsaturated fatty acids—had beneficial evolutionary effects, and supported the selection of increased brain volume and altered microbiome in man [16]. In the present review, we discuss the two sides of red meat consumption by patients with CKD, as illustrated in Figure 1. Furthermore, we present data from a pilot study in which we tested the hypothesis that a low-protein diet (LPD) prescribed for nondialysis CKD patients would reduce the amount of uremic toxins produced by gut microbiota.