Soy protein as part of a low-protein diet is a new direction in cardio- and nephroprotection in patients with 3B–4 stages of chronic kidney disease: prospective, randomized, controlled clinical study

Background. It has been established that the use of a low-protein diet (LPD) in combination with ketoanalogues (KA) of essential amino acids can contribute to cardio- and nephroprotection in chronic kidney disease (CKD). Moreover, it has been shown that replacing part of the animal protein with soy protein (SP) in the diet contributed to more pronounced nephro- and cardioprotection in CKD, however, the data, available in the literature, are mainly represented by experimental studies.

Aim. To compare the effects of 2 types of diets on the main parameters of nephro- and cardioprotection in patients with CKD.

Materials and methods. We have conducted a prospective, randomized, controlled clinical study which included 85 patients with 3B–4 stages of CKD, compliant to LPD (0.6 g of protein/kg body weight) + KA (1 tablet/5 kg body weight). 43 patients (Group 1) received LPD with replacing animal protein with soy (60% soy protein + 40% another vegetable proteins) + KA, and 42 patients (control group, Group 2) received LPD (60% animal protein + 40% vegetable protein) + KA, within 12 months.

Results. The dietary substitution of animal protein with SP to a greater extent delayed the decrease in glomerular filtration rate (-5.9% vs -13.3%; p=0.048), the increase in left ventricular hypertrophy (+4.7% vs +12.3%; p=0.042), as well as the increase in central systolic blood pressure (+2.6% vs +13.0%; p=0.021), augmentation index (+7.6% vs +23.3%; p=0.010), slowed down the decrease in lean body mass in men (+0.9% vs -11.2%; p=0.017) and women (-1.8% vs -10.3%; p=0.024), increase in phosphorus (-10.3% vs +13.0%; p=0.029), cholesterol (-10.7% vs -3.4%; p=0.047) and urea (+6.3% vs +19.6%; p=0.035) serum levels.

Conclusion. The use of LPD with substitution of animal protein with soy protein + KA provides a more pronounced effect on nephro- and cardioprotection as well as maintenance of nutritional status, than conventional LPD + KA in patients with 3B–4 stages of CKD.