Associations between Zinc Deficiency, Taste Changes, and Salivary Flow Rates following Gastric Bypass and Sleeve Gastrectomy Surgeries

Background. The prevalence of taste change (hypogeusia) and its association with zinc deficiency is unclear due to differences in methods of assessment. We investigate the prevalence of hypogeusia using mixed methods and link it with changes in zinc levels following mini gastric bypass (MGB) and sleeve gastrectomy (SG). Methods. This was a prospective observational study of MGB (N = 18) and SG (N = 25). Hypogeusia was evaluated by using a validated questionnaire and by taste strips procedure along with serum zinc levels and salivary flow rate measurements. Results. The mean age was 40.0 ± 9.7 years; 60.5% were female. By using a questionnaire, MGB patients experienced greater hypogeusia than SG at 3 months (72.0% vs 36.0%; (p=0.03)), but not at 6 months (56.0% vs 45.0%; (p=0.74)), respectively. Using taste strips, at 6 months, more MGB patients experienced hypogeusia compared with SG (44.0% vs 11.0%; p=0.03). Zinc level was reduced following MGB at 6 months (85.6 ± 16.9 μgm/dl vs 67.5 ± 9.2 μgm/dl; (P=0.004)) but was increased at 6 months following SG (76.9 ± 11.4 vs 84.9 ± 21.7 μgm/dl). Reduction in the rate of salivary flow was observed in 66.0% and 72.0% of MGB and SG patients, respectively, at 3 months and in 53.0% and 70.0% at 6 months. Conclusion. Taste change is more prevalent following MGB compared with SG, especially at 6 months postoperation which parallel with changes in zinc levels. More than half of all patients who had undergone bariatric surgery (BS) had low to very low salivary flow rates during the follow-up. This study suggests an association between low zinc levels and reduced salivary flow with hypogeusia following BS.