Response to the Letter to the Editor “Bariatric Surgery and the Assessment of Copper and Zinc Nutriture” by Leslie M. Klevay

Excerpt

We thank Dr. Klevay for his interest in our recent article [1] in which we have reported on distinct nutritional deficiencies in severely obese patients, in particular with regard to zinc, 25-OH vitamin D₃, and vitamin B₁₂. From our findings, we concluded that careful nutritional assessment should be performed in all bariatric candidates before surgery. Dr. Klevay points out that obesity-associated subclinical inflammation could be a potential confounder leading to an overestimation of zinc and an underestimation of copper deficiency rates in our study. According to this suggestion, we have now performed some supplementary analyses on our data set. We found that patients with low albumin levels displayed on average higher serum levels of the inflammatory marker “high sensitive C-reactive Protein” (hsCRP; mean ± SD: 14.8 ± 11.6 vs. 8.8 ± 7.1 mg/l; P < 0.001) and lower serum zinc levels (11.1 ± 1.3 vs. 12.4 ± 1.8 μmol/l; P < 0.001) than patients with normal serum albumin levels. Vice versa, patients with zinc deficiency displayed lower albumin levels than patients with normal zinc levels (40.5 ± 4.3 vs. 42.8 ± 4.5 g/l; P = 0.003). Furthermore, correlation analyses revealed a significant positive correlation between serum levels of albumin and zinc (r = 0.30; P < 0.001) as well as inverse correlations between serum albumin and hsCRP levels (r = −0.36; P < 0.001) and between serum hsCRP and zinc levels (r = −0.15; P = 0.032). Taken together, these findings are well in line with the notion of an inhibitory influence of subclinical inflammation on hepatic albumin production. Given that albumin represents the major binding protein of zinc in the circulation, reduced albumin levels could in fact have contributed to the rather high prevalence of zinc deficiency (i.e., 25%) in our study sample. However, it should also be noted that previous studies measuring zinc concentrations in erythrocytes [2] or hair [3] likewise revealed reduced levels in obese subjects, supporting the assumption of poor zinc nutriture in obese subjects as indicated by our report [1]. …