Zinc Plasma Status and Sensory Perception in Nondialysis Chronic Kidney Disease Patients

Objective The aim of this study was to evaluate the association between zinc plasma levels and sensory perception in patients with chronic kidney disease (CKD). Methods A cross-sectional study with 21 nondialysis CKD patients (11 men, 51.1 ± 7.1 years, body mass index 27.9 ± 7.1 kg/m2, estimated glomerular filtration rate 32.7 ± 19.9 mL/min) and 22 non-CKD volunteers (10 men, 49.8 ± 8.3 years, body mass index 28.5 ± 5.4 kg/m2) was conducted. Blood samples were collected to obtain plasma for zinc analysis. Anthropometric and biochemical parameters, as well as food intake and salivary flow rate, were also evaluated. Taste sensory perception for sweet, acidic, bitter, and salty flavors was determined by the “three-drop method,” with 4 concentrations of the 4 basic tastes. Results As expected, zinc plasma levels were significantly lower in CKD patients (70.1 ± 19.2ug/dL) when compared with the control group participants (123.2 ± 24.6 μg dL) (P ˂ .0001). The bitter taste perception was lower in the CKD group (p˂0.0001). Our findings showed that sensitivity to sour (P = .047), salty (P = .03), and bitter tastes was significantly lower in participants with lower zinc plasma levels. Also, bitter taste sensitivity was lower in participants with less zinc intake (P = .038). When grouping control subjects and CKD patients, significant correlations were observed between zinc plasma levels and the number of correct answers for bitter taste (r = 0.49, P = .001), number of correct answers for salty taste (r = 0.30, P = .048), and total score of correct answers (r = 0.30, P = .044). Conclusions Reduced zinc plasma levels in nondialysis CKD patients may be associated with lower perception of bitter, sour, and salty tastes and strategies to restore these levels are crucial due many factors, including food preferences and intake.