A zinc-containing compound, Polaprezinc, is effective for patients with taste disorders: randomized, double-blind, placebo-controlled, multi-center study

Diagnosis and treatment of taste disorders in Japan

Though 270,000 patients with complaints of taste abnormalities visited medical institutions annually in 2019 survey, there are no drugs for the treatment of taste disorders that are covered by health insurance in Japan. In the survey, the number of patients with taste disorders was correlated with age, and the need for medical treatment for taste disorders is expected to increase in the future because of the super-aging society. The pathophysiology of taste disorders varies widely. There is an obvious need to decide the site and the causes of the disorder and understand the mechanism, by performing various examinations. It needs to first adjust the causative systemic diseases and medications in the treatment for taste disorder. Damage of taste cells due to zinc deficiency is the main pathophysiological mechanism of taste disorders, and zinc supplementation is a standard treatment in Japan. Oral zinc therapy is the treatment for taste disorders due to zinc deficiency or idiopathic taste disorder; though a double-blind study was conducted, it was considered low-level evidence in a clinical review. In Japan, the off-label use of polaprezinc for taste disorders was approved in 2011, and zinc acetate hydrate was approved for hypozincemia in March 2017, making it easier to use oral zinc therapy in general. In some cases, psychotherapy or herbal medicine therapy has been used with remarkable success, although its effectiveness has not been clearly tested. It might be expected to offer some help to patients. In the treatment of elderly patients with taste disorders, physicians need to consider the difference between "age-related changes in taste in healthy people" and "taste disorders in elderly persons", and they should separate them. Aggressive treatment is desirable regardless of age, because no significant difference in the efficacy of various treatments was found between patients older and younger than 65 years.

Resting Saliva Volume as a Risk Factor for Hypogeusia: A Retrospective Study

OBJECTIVES

The causes of hypogeusia include zinc deficiency, systemic illness, and consumption of drugs. Notably, patients with oral cavity diseases such as oral candidiasis and salivary gland hypofunction may present with risk factors that remain unreported. Hence, this study aimed to investigate the relationship between age, sex, smoking status, serum zinc concentration, oral candidiasis, saliva volume, and taste function in patients with hypogeusia.

SUBJECTS AND METHODS

Overall, 335 participants who complained of taste abnormalities underwent a taste test. Based on the recognition threshold value, the participants were classified as normal individuals (recognition threshold of 1 and 2) and patients with hypogeusia (recognition threshold of ≥3). The clinical characteristics, including resting saliva volume (RSV) and stimulated saliva volume (SSV), were compared, and a multivariate logistic regression analysis focusing on RSV was performed.

RESULTS

Patients with hypogeusia had a lower RSV than normal individuals for all tastes, but not for SSV. Based on the results of regression analysis, RSV was identified as an independent predictor of hypogeusia for salty and bitter tastes. Moreover, the proportion of patients with decreased RSV increased as the number of taste qualities exceeding the reference recognition threshold increased. Furthermore, a decrease in RSV was associated with an increase in the recognition threshold for salty and bitter tastes.

CONCLUSIONS

Based on the results of the present study, moisturizing the oral cavity may be useful against hypogeusia.

Carnosine and Beta-Alanine Supplementation in Human Medicine: Narrative Review and Critical Assessment

The dipeptide carnosine is a physiologically important molecule in the human body, commonly found in skeletal muscle and brain tissue. Beta-alanine is a limiting precursor of carnosine and is among the most used sports supplements for improving athletic performance. However, carnosine, its metabolite N-acetylcarnosine, and the synthetic derivative zinc-L-carnosine have recently been gaining popularity as supplements in human medicine. These molecules have a wide range of effects—principally with anti-inflammatory, antioxidant, antiglycation, anticarbonylation, calcium-regulatory, immunomodulatory and chelating properties. This review discusses results from recent studies focusing on the impact of this supplementation in several areas of human medicine. We queried PubMed, Web of Science, the National Library of Medicine and the Cochrane Library, employing a search strategy using database-specific keywords. Evidence showed that the supplementation had a beneficial impact in the prevention of sarcopenia, the preservation of cognitive abilities and the improvement of neurodegenerative disorders. Furthermore, the improvement of diabetes mellitus parameters and symptoms of oral mucositis was seen, as well as the regression of esophagitis and taste disorders after chemotherapy, the protection of the gastrointestinal mucosa and the support of Helicobacter pylori eradication treatment. However, in the areas of senile cataracts, cardiovascular disease, schizophrenia and autistic disorders, the results are inconclusive.

Retrospective study on the therapeutic efficacy of zinc acetate hydrate administration to patients with hypozincemia-induced dysgeusia

BACKGROUND

Dysgeusia is a relatively early symptom of zinc deficiency, and zinc replacement is effective in treating dysgeusia. The administration of zinc acetate hydrate (ZAH) was approved in 2017 for patients with hypozincemia in Japan. This retrospective study was conducted to explore the efficacy and safety of ZAH administration in patients with hypozincemia-induced dysgeusia.

METHODS

Patients with hypozincemia-induced dysgeusia who visited our hospital from May 2013 to December 2019 were included in this study. ZAH (zinc content; 50 mg/day) was administered to 42 patients for 24 weeks. The taste test was performed using the filter paper disk method, and the total cognitive thresholds of the left and right chorda tympani regions were used. Changes in taste function, serum zinc and copper levels, and copper/zinc ratio were analyzed. A total of 28 patients who received polaprezinc (PPZ, zinc content; 34 mg/day) for 24 weeks, who were prescribed until ZAH was approved, were registered as controls.

RESULTS

Serum zinc levels at 12 and 24 weeks after ZAH or PPZ administration were higher than those before administration. These levels were significantly higher in the ZAH-treated group than in the PPZ-treated group. However, serum copper levels did not significantly change before and after administration. In the taste test, the taste thresholds for the acidity and salty at 12 and 24 weeks after ZAH administration were significantly decreased compared to before administration. In contrast, in the PPZ group, the taste thresholds for the acidity and salty were significantly decreased 24 weeks after administration.

CONCLUSIONS

ZAH (50 mg/day) administration was effective in improving the gustatory sensitivity of patients with dysgeusia and hypozincemia 12 weeks after administration without affecting the serum copper level. ZAH was also more effective than PPZ.

The Effectiveness of Zinc Supplementation in Taste Disorder Treatment: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Introduction

Food taste and flavour affect food choice and acceptance, which are essential to maintain good health and quality of life. Reduced circulating zinc levels have been shown to adversely affect the taste, but the efficacy of zinc supplementation to treat disorders of taste remains unclear. In this systematic review and meta-analysis, we aimed to examine the efficacy of zinc supplementation in the treatment of taste disorders.

Methods

We searched four electronic bibliographical databases: Ovid MEDLINE, Ovid Embase, Ovid AMAD, and PubMed. Article bibliographies were also searched, which yielded additional relevant studies. There were no restrictions on the publication date to facilitate the collection and identification of all available and relevant articles published before 7 February 2021. We performed a systematic review and meta-analysis according to the PRISMA Statement. This review was registered at PROSPERO and given the identification number CRD42021228461.

Results

In total, we included 12 randomized controlled trials with 938 subjects. The intervention includes zinc (sulfate, gluconate, picolinate, polaprezinc, and acetate), and the pooled results of the meta-analysis of subjects with idiopathic and zinc-deficient taste disorder indicate that improvements in taste disorder occurred more frequently in the experimental group compared to the control group (RR = 1.38; 95% CI: 1.16, 1.64, p=0.0002). Zinc supplementation appears to confer a greater improvement in taste perception amongst those with chronic renal disease using zinc acetate (overall RR = 26.69, 95% CI = 5.52-129.06, p < 0.0001). The doses are equivalent to 17 mg-86.7 mg of elemental zinc for three to six months.

Conclusion

Zinc supplementation is an effective treatment for taste disorders in patients with zinc deficiency, idiopathic taste disorders, and in patients with taste disorders induced by chronic renal failure when given in high doses ranging from 68 to 86.7 mg/d for up to six months.

A Literature Review of Taste Change and Zinc Deficiency After Bariatric Surgery: Could There Be a Causal Link?

In this review, we collated evidence relating to taste change and zinc deficiency in relation to bariatric surgery (BS) and effects of zinc replacement on taste perception and speculate on the possible role of zinc deficiency to induce taste change after BS. A literature search was conducted (33 studies, N = 3264). We showed that taste change and zinc deficiency are frequent complications after BS, which both typically occurred at 6 months post-surgery. Our analysis did not support a causal link between the two, but similar onset of incidences indirectly indicates a link. Supplementation with 45-50 mg of zinc sulphate, higher than current recommendation, was effective in improving taste. Further studies are required to establish the causal link between the two in the context of BS.

How to Manage Taste Disorders

Purpose of the Review

This study aims to summarize the current state of the art of how taste disorders are clinically best managed.

Recent Findings

Taste disorders are distressing for the concerned patients since eating and drinking become bothersome or impossible. Apart from nutritional problems, quality of life is impaired. Still, diagnosis and treatment of taste disorders are elusive, and general knowledge about taste and its affection is little within the population and the medical community. This review stresses the importance of accurate workup and diagnosis of taste disorders in order to offer an effective treatment. Yet unclear aspects of taste disorders are discussed, and interesting findings regarding the treatment of taste disorders are reviewed. A special focus is given to current pharmacological options on how to treat taste disorders.

Summary

Despite impressive insights into the gustatory function and molecular logic of taste receptor cells, there is currently poor clinical knowledge on the pathophysiology of taste disorders in humans. Diagnosing, measuring, and treating gustatory disorders remain restricted to a handful of specialized smell and taste centers worldwide. Despite interesting work on potential drugs treating taste disorders, many of the reported medications lack controlled and randomized trials confirming their efficacy in taste dysfunction. Future efforts need to be focused on the treatment of taste disorders.

Ethyl loflazepate as a treatment for patients with idiopathic and psychogenic taste disorder

Background

Ethyl loflazepate (EL) is a benzodiazepine derivative that has been reported to activate the gustatory cortex. Our department routinely uses EL as a first-line treatment for idiopathic and psychogenic taste disorders, although little has been reported in the literature with respect to patient outcomes, so we conducted a retrospective study examining its safety and efficacy.

Methods

Between 2008 and 2020, 49 patients (14 males and 35 females; mean age, 62.1 years) were diagnosed with taste disorders and received EL as their only treatment for > 14 days. Severity of taste disorder was evaluated using the paper disc method by Sakai et al., and treatment efficacy was evaluated using the Visual Analog Scale, wherein patients gave subjective ratings for their symptoms (reductions by > 50% after administration of EL for 4 weeks were defined as improvements).

Results

Results showed that the improvement rates for patients with idiopathic and psychogenic taste disorders were 55 and 70%, respectively. Additionally, the majority (78%) improved within 2 weeks, and side effects were mild (seven cases with drowsiness and one case with dizziness).

Conclusions

We conclude that EL is an appropriate first-line medication for patients with idiopathic and psychogenic taste disorders.

Zinc carnosine: Frontiers advances of supplement for cancer therapy

Zinc (Zn) has an existence within large quantities in the human brain, while accumulating within synaptic vesicle. There is growing evidence that Zn metabolic equilibrium breaking participates into different diseases (e.g., vascular dementia, carcinoma, Alzheimer's disease). Carnosine refers to an endogenic dipeptide abundant in skeletal muscle and brains and exerts a variety of positive influences (e.g., carcinoma resistance, crosslinking resistance, metal chelation and oxidation limitation). A complex of Zn and carnosine, called Zinc-L-carnosine (ZnC), has been extensively employed within Zn supplement therapeutic method and the treating approach for ulcers. ZnC has been shown to play a variety of roles in the body, including inhibiting intracellular reactive oxygen species(ROS) and free radical levels, inhibiting inflammation, supplementing zinc enzymes and promoting wound healing and mucosal cell repair. The present study conducting a reviewing process for the advances of ZnC in tumor adjuvant therapy.

Oral adverse events due to zinc deficiency after pancreaticoduodenectomy requiring continuous intravenous zinc supplementation: a case report and literature review

Background

Zinc is mainly absorbed in the duodenum and proximal jejunum, which are removed during pancreaticoduodenectomy (PD). Little is known about the adverse oral events and skin disorders caused by zinc deficiency after PD. Herein, we reviewed studies on the development of zinc deficiency after PD and reported about a patient with zinc deficiency after PD who required home intravenous zinc replacement.

Case presentation

A 73-year-old woman with glossitis, taste disorder, and acrodermatitis enteropathica-like eruption on her fingers presented to the Division of Dentistry and Oral Surgery 69 days after PD. Her serum zinc level markedly decreased to 30 μg/dL. Oral zinc administration was inadequate to treat hypozincemia after PD; therefore, multi-trace elements were injected intravenously during readmission. Her serum zinc levels recovered, and her lesions gradually improved. Furthermore, a central venous port was implanted to maintain normal serum zinc levels, and she continued self-injecting zinc at home.

Conclusions

Zinc deficiency after PD rarely occurs. The clinical oncologist community, including dentists responsible for the oral care of cancer patients, should be aware of the oral adverse events, such as dysgeusia, glossitis, and oral pain, associated with zinc deficiency after cancer surgery and that induced by chemotherapy or head and neck radiation therapy.

Gustatory and Saliva Secretory Dysfunctions in COVID-19 Patients with Zinc Deficiency

Given the ever-progressing studies on coronavirus disease 2019 (COVID-19), it is critical to update our knowledge about COVID-19 symptomatology and pathophysiology. In the present narrative review, oral symptoms were overviewed using the latest data and their pathogenesis was hypothetically speculated. PubMed, LitCovid, ProQuest, and Google Scholar were searched for relevant studies from 1 April 2021 with a cutoff date of 31 January 2022. The literature search indicated that gustatory dysfunction and saliva secretory dysfunction are prevalent in COVID-19 patients and both dysfunctions persist after recovery from the disease, suggesting the pathogenic mechanism common to these cooccurring symptoms. COVID-19 patients are characterized by hypozincemia, in which zinc is possibly redistributed from blood to the liver at the expense of zinc in other tissues. If COVID-19 induces intracellular zinc deficiency, the activity of zinc-metalloenzyme carbonic anhydrase localized in taste buds and salivary glands may be influenced to adversely affect gustatory and saliva secretory functions. Zinc-binding metallothioneins and zinc transporters, which cooperatively control cellular zinc homeostasis, are expressed in oral tissues participating in taste and saliva secretion. Their expression dysregulation associated with COVID-19-induced zinc deficiency may have some effect on oral functions. Zinc supplementation is expected to improve oral symptoms in COVID-19 patients.

A clinical survey on patients with taste disorders in Japan: A comparative study

OBJECTIVE

To investigate changes in the clinical state of taste disorders between 1990, 2003, and 2019 using the same methodology as that in previous studies.

MATERIALS AND METHODS

In June 2019, we mailed a questionnaire to 1100 otolaryngologists belonging to the Japan Society of Stomato-pharyngology and investigated three question categories: "Institution", "Number of patients for 3 months", and "Treatment". In addition, we analyzed some results by the class of institution.

RESULTS

The rate of patients who complained of taste disorders in the 2019 survey (220/100,000 persons/year) was twice that of the 1990 survey (110/100,000 persons/year), and slightly higher than that of the 2003 survey (192/100,000 persons/year). The rate of female patients was higher than that of male patients in all age groups. The number of patients was correlated with age up to 70 years of age in both genders. The rates of performing taste tests to assess taste function in the 2019 survey were significantly decreased compared with a 2003 survey (electrogustometry: p<0.001, filter paper disk method: p<0.05 in university). The rate of examination of the serum zinc in the 2019 survey was increased compared with the 1990 survey (p<0.001). Zinc oral therapy was used for the treatment of taste disorders in 239/299 (79.9%) patients/institutes for 3 months. In addition, 213 institutions (69.6%) answered that zinc oral therapy was efficacious for taste disorders.

CONCLUSION

The patients who complained of taste disorder have increased. The zinc administration is an appropriate clinical treatment for taste disorders in Japan. To enhance treatment for taste disorders, simpler methods for assessing taste function need to be developed, and the pathological mechanisms of taste disorders other than zinc deficiency need to be clarified.

Study on the Local Anti-Osteoporosis Effect of Polaprezinc-Loaded Antioxidant Electrospun Membrane

Background

Compared with the healthy condition, osteoporotic bone defects are often accompanied by poor osteogenesis and excessive reactive oxygen species (ROS), which pose serious challenges to bone augmentation and repair by normal resorbable guided bone regeneration (GBR) membrane.

Purpose

Polaprezinc (PZ) was loaded into polycaprolactone/gelatin (PG) hybrid electrospun nanofibers to fabricate a GBR membrane with antioxidant and osteogenesis ability.

Methods

A series of physicochemical characterization were performed by scanning electron microscopy, Fourier-transform infrared spectroscopy, and water contact angle measurement. In addition to membrane degradation and PZ release detection, membranes were tested for cell viability, differentiation, and protein expression in MC3T3-E1 cells by CCK8, alkaline phosphatase activity, mineralization, and Western blotting assays. The membrane osteogenic capacity in cranial bone defects was studied by micro-CT in vivo.

Results

PZ was successfully doped into the PCL/GEL nanofibers to form a hydrophilic GBR membrane. The cumulative release of PZ was closely related to the membrane degradation behavior. PG/0.4%PZ membranes produced the best protective effect on cell proliferation/differentiation under oxidative stress microenvironment; however, the PG/0.8%PZ membrane was cytotoxic. Western blotting demonstrated that the PZ-loaded membrane upregulated the Nrf2/HO-1/SOD1 signaling molecules in a concentration-dependent manner. In addition, micro-CT results showed an abundant formation of new bones in the PG/0.4%PZ group compared to the PG group.

Conclusion

PZ-loaded degradable PG membranes (especially PG/0.4%PZ) have great potential to accelerate bone regeneration in oxidative stress-related diseases.

Multicenter, prospective, observational study of chemotherapy-induced dysgeusia in gastrointestinal cancer

PURPOSE

Dysgeusia is an adverse event caused by chemotherapy. Although retrospective studies have shown zinc administration improves dysgeusia, there have been no prospective studies. The present study examined effects of zinc therapy on dysgeusia in patients with gastrointestinal cancer.

METHODS

This multicenter, prospective, observational study enrolled patients with dysgeusia during chemotherapy treatment. Patients received no intervention (control), polaprezinc p.o., or zinc acetate hydrate p.o., and serum zinc levels were measured at 0 (baseline), 6, and 12 weeks. Dysgeusia was assessed using CTCAE v5.0 and subjective total taste acuity (STTA) criteria using questionnaires at baseline and 12 weeks.

RESULTS

From February 2020 to June 2021, 180 patients were enrolled from 17 institutes. There were no differences in mean baseline serum zinc levels among the groups (67.3, 66.6, and 67.5 μg/dL in the no intervention, polaprezinc, and zinc acetate hydrate groups, respectively. P = 0.846). The changes in mean serum zinc levels after 12 weeks were - 3.8, + 14.3, and + 46.6 μg/dL, and the efficacy rates of dysgeusia were 33.3%, 36.8%, and 34.6% using CTCAE and 33.3%, 52.6%, 32.7% using STTA in the no intervention, polaprezinc, and zinc acetate hydrate groups, respectively. The STTA scores improved in all groups, with significant improvement observed in the polaprezinc group compared with the no intervention group (P = 0.045).

CONCLUSION

There was no significant correlation between the degree of serum zinc elevation and improvement in dysgeusia, suggesting that polaprezinc, but not zinc acetate hydrate, was effective in improving chemotherapy-induced dysgeusia.

TRIAL REGISTRATION

UMIN000039653. Date of registration: March 2, 2020.

Recent advances on polaprezinc for medical use (Review)

The present study described the chemical and biological properties of zinc complex of L-carnosine (L-CAZ; generic name, polaprezinc; chemical name, catena-(S)-[µ-[N(α)-(3-aminopropionyl) histidinato (2-) N1, N2, O: N(τ)]-zinc], molecular formula, C₉H₁₄N₄O₃Zn; molecular weight, 291.6404; CAS registry number, 107667-60-7). Characterized as a white or yellowish white crystalline powder, this drug is insoluble in glacial acetic acid and almost insoluble in water, methanol, ethanol and ether. It is soluble in dilute hydrochloric acid, dilute nitric acid and sodium hydroxide solution, and its melting point is 260-270˚C. Polaprezinc is an anti-ulcer drug that was jointly studied and developed by Hamari Chemicals Co., Ltd. and Zeria Pharmaceutical Co., Ltd., and was first approved in Japan in 1994. This review article summarizes the research advances of polaprezinc, including the patents, preparations, synthetic routes, pharmacokinetics, pharmacological effects and application in clinical research.

Therapeutic supplementation with zinc in the management of COVID-19-related diarrhea and ageusia/dysgeusia: mechanisms and clues for a personalized dosage regimen

Zinc supplementation is indicated for diarrhea and taste disorders, which are both features of COVID-19. Nevertheless, this strategy has not been tested for the treatment of these secondary complications in the current pandemic. Through an updated review, a practical appraisal was considered as a means of providing a medical nexus of therapeutic zinc regimens as an adjunct in the management of COVID-19–related diarrhea and ageusia/dysgeusia. While diarrhea and taste disorders are consequences of COVID-19, zinc supplementation is useful for non–COVID-19 patients with these clinical problems. The overwhelming evidence for supplementing with zinc in diarrhea and pneumonia is associated with the treatment of children, while for taste disorders the use of supplementing with zinc is more examined in adults. Whereas COVID-19 is more prevalent in adults, precautions should be exercised not to translate the zinc dosage used for children with diarrhea and taste disorders into the current pandemic. Therapeutic doses of zinc used for adults (∼50–150 mg/day of elemental zinc) could be included in the treatment strategies for COVID-19, but this proposal should be examined through randomized studies.

Association of Zinc Deficiency with Development of CVD Events in Patients with CKD

Deficiency of the micronutrient zinc is common in patients with chronic kidney disease (CKD). The aim of this review is to summarize evidence presented in literature for consolidation of current knowledge regarding zinc status in CKD patients, including those undergoing hemodialysis. Zinc deficiency is known to be associated with various risk factors for cardiovascular disease (CVD), such as increased blood pressure, dyslipidemia, type 2 diabetes mellitus, inflammation, and oxidative stress. Zinc may protect against phosphate-induced arterial calcification by suppressing activation of nuclear factor kappa light chain enhancer of activated B. Serum zinc levels have been shown to be positively correlated with T₅₀ (shorter T₅₀ indicates higher calcification propensity) in patients with type 2 diabetes mellitus as well as those with CKD. Additionally, higher intake of dietary zinc was associated with a lower risk of severe abdominal aortic calcification. In hemodialysis patients, the beneficial effects of zinc supplementation in relation to serum zinc and oxidative stress levels was demonstrated in a meta-analysis of 15 randomized controlled trials. Thus, evidence presented supports important roles of zinc regarding antioxidative stress and suppression of calcification and indicates that zinc intake/supplementation may help to ameliorate CVD risk factors in CKD patients.

Polaprezinc for prevention of oral mucositis in patients receiving chemotherapy followed by hematopoietic stem cell transplantation: A multi-institutional randomized controlled trial

Oral mucositis is a common and distressing complication in patients receiving high-dose chemotherapy followed by hematopoietic stem cell transplantation (HSCT). We reported previously in a single-center retrospective analysis that zinc-L-carnosine (polaprezinc [PZ]) reduced the incidence of oral mucositis associated with HSCT. To verify the accuracy of the prophylactic effect of PZ against oral mucositis, we carried out a multi-institutional prospective randomized controlled study. Patients were randomly allocated to either the prevention group, in which PZ lozenge treatment was started before chemotherapy, or the control group, in which administration of PZ lozenges was initiated immediately after the onset of Grade 2 oral mucositis. Oral mucositis was evaluated daily from the start of chemotherapy to 35 days after transplantation. A total of 91 patients were enrolled, and 88 patients (47 in the control group and 41 in the prevention group) were eligible for data analysis. The incidence of Grade ≥2 but not Grade ≥3 oral mucositis was significantly reduced in the prevention group compared to the control group (44.7% in control group vs 22.0% in the prevention group, P = .025). There were no significant differences in the incidence rates of other adverse events or the rate of engraftment (95.6% vs 97.2%, P = .693) between the two groups. These findings suggest that PZ lozenge is effective for prophylaxis against Grade ≥2 oral mucositis associated with chemotherapy in patients undergoing HSCT without any influence on the HSCT outcome.

Prognostic factors of recovery with medication in patients with taste disorders

Objectives

We aimed to elucidate the prognostic factors of the patients with taste disorders who were treated with popular and common medication in Japan.

Materials and methods

A retrospective study on the medical charts of a total of 255 patients with taste disorders who were treated primarily with oral medication including a zinc agent.

Results

The factors below were significantly linked with poor prognosis: 1) male gender, 2) taste disorders that began 3 months before starting treatment and 3) a severe taste disorder grade at the initial visit.

Conclusions

We have concluded that the prognosis for the patients with taste disorders who were treated by popular and standard medication therapy in Japan recently was significantly linked to gender, the period of 3 months before starting the treatment and the severity of the disorder at the time of diagnosis. In addition, we recognized some limitations we should resolve in further research including a method of measuring “umami” and so on.

Clinical relevance

Better awareness of these factors should be clinically useful when we manage patients with taste disorders. Earlier treatment should be started to cure the symptoms.

Radiation-Induced Oral Mucositis in Head and Neck Cancer Patients. Five Years Literature Review

Backround: Radiation-induced oral mucositis consists of a series of relatively frequent side effects after head and neck cancer radiotherapy and has an adverse impact on both regular treatment process and the quality of life of patients.

OBJECTIVE

The purpose of the present review is to optimize the current management of radiation-induced oral mucositis in head and neck cancer patients.

METHODS

PubMed database research was performed on articles published since 2015 that demonstrated efficacy in the management of radiation-induced oral mucositis in head and neck cancer patients. The study selection included observational, prospective, comparative, randomized, double- blind, placebo-controlled or uncontrolled, and retrospective studies, as well as systematic reviews and metanalyses.

RESULTS

From the 931 citations obtained from the search, only 94 articles met the inclusion criteria, including mucosal protectants, anti-inflammatory agents, growth factors, and various miscellaneous and natural agents. Several methods, including both pharmacological and natural agents, have been proposed for the management of oral mucositis. In addition to the already known interventions with strong evidence, according to the Multinational Association of Supportive Care in Cancer and he International Society of Oral Oncology guidelines, further agents have been used. However, a great number of them lack clear evidence, which surely requires the design of more controlled clinical trials for a better assessment of the ideal methods.

CONCLUSION

The management of oral mucositis constitutes an active area of research. In light of these results, it is aimed to illustrate those treatment strategies that are most effective regarding the treatment approach of oral mucositis.

Japan's Practical Guidelines for Zinc Deficiency with a Particular Focus on Taste Disorders, Inflammatory Bowel Disease, and Liver Cirrhosis

Zinc deficiency is common in Japan, yet awareness on this disorder is lacking. The Japanese Society of Clinical Nutrition recently issued the Japan’s Practical Guideline for Zinc Deficiency 2018 setting forth criteria for diagnosing zinc deficiency, i.e., (a) one or more symptoms of zinc deficiency or low serum alkaline phosphatase, (b) ruling out other diseases, (c) low serum zinc, and (d) alleviation of symptoms upon zinc administration. Serum zinc <60 μg/dL and 60–80 μg/dL indicate zinc deficiency and marginal deficiency, respectively. Zinc deficiency symptoms vary and include dermatitis and taste disorders among others. Zinc administration improves taste in 50–82% of patients suffering from taste disorders (a common symptom of zinc deficiency). Effects of zinc administration do not appear immediately, and therapy should be continued for at least three months. Zinc deficiency often accompanies various diseases and conditions. Here, we focus on inflammatory bowel diseases and liver cirrhosis. As zinc deficiency enhances intestinal inflammation via macrophage activation, we discuss the pathological mechanism for inflammation and zinc deficiency in the context of IBD. Zinc deficiency can also lead to a nitrogen metabolic disorder in patients with liver cirrhosis. Zinc supplementation can improve not only the ammonia metabolism, but also the protein metabolism. We also discuss directions for future studies of zinc deficiency.

Efficacy and Safety of Polaprezinc (Zinc Compound) on Zinc Deficiency: A Systematic Review and Dose-Response Meta-Analysis of Randomized Clinical Trials Using Individual Patient Data

Zinc intake is recommended for zinc deficiency. In clinical practice, polaprezinc has been used as a zinc replacement therapy for zinc deficiency. However, the efficacy of polaprezinc has not been established. To confirm the efficacy on zinc deficiency of polaprezinc and provide additional information on an appropriate regimen, we conducted a systematic review using individual patient data (IPD). We searched PubMed, the Japanese database Ichushi, and the database owned by the marketing authorization holder of polaprezinc. Randomized placebo-controlled trials that reported the serum zinc concentration were eligible. The mean difference of the change from baseline in serum zinc concentration was estimated using a fixed-effects model. The linear dose-response relationship and the subgroup effects were also assessed. Out of 54 unique randomized clinical trials (RCTs), four studies met the eligibility criteria, and we could access IPD for all of them. All three doses of polaprezinc (75 mg, 150 mg, and 300 mg) and the placebo group were examined. The dose-combined overall polaprezinc increased the change from baseline by a mean of 9.08 µg/dL (95% confidence interval: 5.46, 12.70; heterogeneity: I2 = 0.61%) compared to the placebo. A significant dose-response relationship was confirmed (p < 0.001). Baseline serum zinc concentration was considered an effect modifier in polaprezinc 300 mg. All doses of polaprezinc were tolerable, but a dose-response relationship with adverse events (AEs) was observed in gastrointestinal disorders. The dose of 300 mg may be useful among patients with baseline serum zinc concentration of less than 70 µg/dL, and 150 mg for 70 µg/dL or more.

A Review of Zinc-L-Carnosine and Its Positive Effects on Oral Mucositis, Taste Disorders, and Gastrointestinal Disorders

Zinc-L-carnosine (ZnC), also called polaprezinc known as PepZin GI™, is a chelated compound that contains L-carnosine and zinc. It is a relatively new molecule and has been associated with multiple health benefits. There are several studies that support ZnC’s benefits in restoring the gastric lining, healing other parts of the gastrointestinal (GI) tract, improving taste disorders, improving GI disorders, and enhancing skin and liver. Oral mucositis is a common complication of cytotoxic radiotherapy and/or chemotherapy. It occurs in almost every person with head and neck cancer who receive radiotherapy. It is often overlooked because it is not considered life threatening. However, mucositis often leads to a decreased quality of life and cessation of treatment, ultimately decreasing positive outcomes. Therefore, solutions to address it should be considered. The primary mechanisms of action are thought to be localized and related to ZnC’s anti-inflammatory and antioxidant functions. Therefore, the purpose of this review is to discuss the research related to ZnC and to explore its benefits, especially in the management of conditions related to damaged epithelial cells, such as oral mucositis. Evidence supports the safety and efficacy of ZnC for the maintenance, prevention, and treatment of the mucosal lining and other epithelial tissues. The research supports its use for gastric ulcers (approved in Japan) and conditions of the upper GI and suggests other applications, particularly for oral mucositis.

Effect of monosodium L-glutamate (umami substance) on cognitive function in people with dementia

Background/objectives

This study assessed the effect of continuous ingestion of monosodium l-glutamate (MSG) on cognitive function and dietary score in dementia patients.

Subjects/methods

This was a single-blind, placebo-controlled trial involving 159 subjects with dementia residing in a hospital or nursing home. We assigned the subjects to a group that ingested MSG thrice daily (0.9 g/dose) (MSG group; n = 79) or a group that ingested NaCl thrice daily (0.26 g/dose) (Control group; n = 80). This study consisted of a 12-week intake period, followed by a 4-week follow-up period without the ingestion of MSG or NaCl. We performed physical examination, cognitive symptom tests (the Touch Panel-type Dementia Assessment Scale (TDAS) and Gottfries–Bråne–Steen Scale (GBSS)), palatability and behaviour questionnaires, and blood tests before and after the intervention and after the follow-up period.

Results

There were no significant differences in the TDAS and GBSS total scores between the groups before and after the intervention. However, regarding the TDAS sub-items, “the accuracy of the order of a process” did not deteriorate in the MSG group compared with that observed in the Control group (p < 0.05). At the follow-up assessment, the TDAS total scores in the MSG group showed significant improvement compared with those reported in the Control group (p < 0.05). Furthermore, there was a correlation of changes from pre-intervention to post-intervention between the TDAS and enjoyment of the meal (r = −0.299, p = 0.049).

Conclusions

Our results suggest that continued ingestion of MSG has an effect on cognitive function. Furthermore, the patients with improved questionnaires about palatability survey showed greater improvement in cognitive function.

Utility of polaprezinc in reducing toxicities during radiotherapy: a literature review

Chemoradiotherapy is important for treating malignancies. However, radiation-induced toxicities develop as chemoradiotherapy-related complications. Various agents reduce or prevent toxicities, but there are no standard treatments. Polaprezinc (PZ), a chelating compound used for gastric ulcers, has antioxidant and free radical scavenging effects. Although few studies have evaluated PZ and radiation-induced normal tissue damage, several clinical studies have shown the efficacy of PZ for oral mucositis, esophagitis, proctitis and taste alterations during and after radiotherapy. Moreover, preclinical data support the clinical data, indicating good potential of testing PZ in future trials. However, as there are only few well-documented review articles on PZ use in cancer treatment, we conducted this literature review. PZ reduced several radiation-induced toxicities and improved the quality of life.

Zinc, Carnosine, and Neurodegenerative Diseases

Zinc (Zn) is abundantly present in the brain, and accumulates in the synaptic vesicles. Synaptic Zn is released with neuronal excitation, and plays essential roles in learning and memory. Increasing evidence suggests that the disruption of Zn homeostasis is involved in various neurodegenerative diseases including Alzheimer's disease, a vascular type of dementia, and prion diseases. Our and other numerous studies suggest that carnosine (β-alanyl histidine) is protective against these neurodegenerative diseases. Carnosine is an endogenous dipeptide abundantly present in the skeletal muscles and in the brain, and has numerous beneficial effects such as antioxidant, metal chelating, anti-crosslinking, and anti-glycation activities. The complex of carnosine and Zn, termed polaprezinc, is widely used for Zn supplementation therapy and for the treatment of ulcers. Here, we review the link between Zn and these neurodegenerative diseases, and focus on the neuroprotective effects of carnosine. We also discuss the carnosine level in various foodstuffs and beneficial effects of dietary supplementation of carnosine.

Interventions for managing taste disturbances

BACKGROUND

The sense of taste is very much essential to the overall health of an individual. It is a necessary component to enjoy one's food, which in turn provides nutrition to an individual. Any disturbance in taste perception can hamper quality of life in such patients by influencing their appetite, body weight and psychological well-being. Taste disorders have been treated using different modalities of treatment and there is no consensus for the best intervention. Hence this Cochrane Review was undertaken. This is an update of the Cochrane Review first published in November 2014.

OBJECTIVES

To assess the effects of interventions for the management of patients with taste disturbances.

SEARCH METHODS

Cochrane Oral Health's Information Specialist searched the following databases: Cochrane Oral Health's Trials Register (to 4 July 2017); the Cochrane Central Register of Controlled Trials (CENTRAL; 2017 Issue 6) in the Cochrane Library (searched 4 July 2017); MEDLINE Ovid (1946 to 4 July 2017); Embase Ovid (1980 to 4 July 2017); CINAHL EBSCO (1937 to 4 July 2017); and AMED Ovid (1985 to 4 July 2017). The US National Institutes of Health Ongoing Trials Register ClinicalTrials.gov (www.clinicaltrials.gov) and the World Health Organization International Clinical Trials Registry Platform were searched for trials. Abstracts from scientific meetings and conferences were searched on 25 September 2017. No restrictions were placed on the language or date of publication when searching the electronic databases.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) comparing any pharmacological agent with a control intervention or any non-pharmacological agent with a control intervention. We also included cross-over trials in the review.

DATA COLLECTION AND ANALYSIS

Two pairs of review authors independently, and in duplicate, assessed the quality of trials and extracted data. Wherever possible, we contacted trial authors for additional information. We collected adverse events information from the trials.

MAIN RESULTS

We included 10 trials (581 participants), nine of which we were able to include in the quantitative analyses (566 participants). We assessed three trials (30%) as having a low risk of bias, four trials (40%) at high risk of bias and three trials (30%) as having an unclear risk of bias. We only included studies on taste disorders in this review that were either idiopathic, or resulting from zinc deficiency or chronic renal failure.Of these, nine trials with 544 people compared zinc supplements to placebo for patients with taste disorders. The participants in two trials were children and adolescents with respective mean ages of 10 and 11.2 years and the other seven trials had adult participants. Out of these nine, two trials assessed the patient-reported outcome for improvement in taste acuity using zinc supplements (risk ratio (RR) 1.40, 95% confidence interval (CI) 0.94 to 2.09; 119 participants, very low-quality evidence). We meta-analysed for taste acuity improvement using objective outcome (continuous data) in idiopathic and zinc-deficient taste disorder patients (standardised mean difference (SMD) 0.44, 95% CI 0.23 to 0.65; 366 participants, three trials, very low-quality evidence). We also analysed one cross-over trial separately using the first half of the results for taste detection (mean difference (MD) 2.50, 95% CI 0.93 to 4.07; 14 participants, very low-quality evidence), and taste recognition (MD 3.00, 95% CI 0.66 to 5.34; 14 participants, very low-quality evidence). We meta-analysed taste acuity improvement using objective outcome (dichotomous data) in idiopathic and zinc-deficient taste disorder patients (RR 1.42, 95% 1.09 to 1.84; 292 participants, two trials, very low-quality evidence). Out of the nine trials using zinc supplementation, four reported adverse events like eczema, nausea, abdominal pain, diarrhoea, constipation, decrease in blood iron, increase in blood alkaline phosphatase, and minor increase in blood triglycerides.One trial tested taste discrimination using acupuncture (MD 2.80, 95% CI -1.18 to 6.78; 37 participants, very low-quality evidence). No adverse events were reported in the acupuncture trial.None of the included trials could be included in the meta-analysis for health-related quality of life in taste disorder patients.

AUTHORS' CONCLUSIONS

We found very low-quality evidence that was insufficient to conclude on the role of zinc supplements to improve taste acuity reported by patients and very low-quality evidence that zinc supplements improve taste acuity in patients with zinc deficiency/idiopathic taste disorders. We did not find any evidence to conclude the role of zinc supplements for improving taste discrimination, or any evidence addressing health-related quality of life due to taste disorders.We found very low-quality evidence that is not sufficient to conclude on the role of acupuncture for improving taste discrimination in cases of idiopathic dysgeusia (distortion of taste) and hypogeusia (reduced ability to taste). We were unable to draw any conclusions regarding the superiority of zinc supplements or acupuncture as none of the trials compared these interventions.

Antioxidant, Anti-inflammatory, and Genomic Stability Enhancement Effects of Zinc l-carnosine: A Potential Cancer Chemopreventive Agent?

Cancer is one of the major causes of death worldwide, and the incidence and mortality rates of cancer are expected to rise tremendously in the near future. Despite a better understanding of cancer biology and advancement in cancer management, current strategies in cancer treatment remain costly and ineffective. Hence, instead of putting more efforts to search for new cancer cures, attention has now been shifted to the development of cancer chemopreventive agents as a preventive measure for cancer formation. It is well known that neoplastic transformation of cells is multifactorial, and the occurrence of oxidative stress, chronic inflammation, and genomic instability events has been implicated in the carcinogenesis of cells. Zinc l-carnosine (ZnC), which is clinically used as gastric ulcer treatment in Japan, has been suggested to have the potential in preventing cancer development. Multiple studies have revealed that ZnC possesses potent antioxidant, anti-inflammatory, and genomic stability enhancement effects. Thus, this review provides some mechanistic insight into the antioxidant, anti-inflammatory, and genomic stability enhancement effects of ZnC in relevance to its chemopreventive potential.

Validity of the copper/zinc ratio as a diagnostic marker for taste disorders associated with zinc deficiency

Although zinc (Zn) deficiency is often suspected in patients with taste disorders, it may be difficult to diagnose Zn deficiency, especially in patients without any clear risk factors. Accordingly, the aim of the present study was to detect possible markers for taste disorders or zinc deficiency. To achieve this aim, we analyzed data obtained from 122 Japanese men who were not using medicines and had no diseases requiring treatment. We evaluated the following factors: awareness of dysgeusia; salty taste recognition threshold (SRT); the serum concentrations of Zn, copper (Cu), iron, alkaline phosphatase, and albumin; and the Cu/Zn ratio. The serum Cu/Zn ratio was positively correlated with the both the SRT and the awareness of dysgeusia. The serum Zn concentration was not correlated with the SRT or the awareness of dysgeusia in univariate analyses. However, in multivariate logistic regression, the serum Zn concentration was associated with the awareness of dysgeusia. In conclusion, the serum Cu/Zn ratio is a good diagnostic marker for taste disorders and the value of 1.1 may be a threshold level for detecting taste disorders.

Traumatic Dysgeusia, an Unusual Complication of Facial Trauma: A Case Report

The chemical senses of taste and smell are important to human life, because they play an important role in detecting potential environmental hazards. Humans can identify countless different flavors by the simultaneous perception of taste and smell. Reports of sensory loss after craniocerebral trauma began to appear in the medical literature in the middle 1800s. Dysgeusia associated with head injuries is rare and its reported incidence is 0.4 to 0.5%. This report describes the clinical case of a 32-year-old man with Le Fort I and III fractures treated with surgical reduction and fixation. The patient presented with dysgeusia after slight improvement of his preoperative anosmia. The prognosis is favorable and the treatment is prospective.

Interventions for the management of taste disturbances

BACKGROUND

The sense of taste is very much essential to the overall health of the individual. It is a necessary component to enjoying one's food, which in turn provides nutrition to an individual. Any disturbance in taste perception can hamper the quality of life in such patients by influencing their appetite, body weight and psychological well-being. Taste disorders have been treated using different modalities of treatment and there is no consensus for the best intervention. Hence this Cochrane systematic review was undertaken.

OBJECTIVES

To assess the effects of interventions for the management of patients with taste disturbances.

SEARCH METHODS

We searched the Cochrane Oral Health Group Trials Register (to 5 March 2014), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library Issue 1, 2014), MEDLINE via OVID (1948 to 5 March 2014), EMBASE via OVID (1980 to 5 March 2014), CINAHL via EBSCO (1980 to 5 March 2014) and AMED via OVID (1985 to 5 March 2014). We also searched the relevant clinical trial registries and conference proceedings from the International Association of Dental Research/American Association of Dental Research (to 5 March 2014), Association for Research in Otolaryngology (to 5 March 2014), the US National Institutes of Health Trials Register (to 5 March 2014), metaRegister of Controlled Trials (mRCT) (to 5 March 2014), World Health Organization's International Clinical Trials Registry Platform (WHO ICTRP) (to 5 March 2014) and International Federation of Pharmaceutical Manufacturers and Associations (IFPMA) Clinical Trials Portal (to 5 March 2014).

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) comparing any pharmacological agent with a control intervention or any non-pharmacological agent with a control intervention. We also included cross-over trials in the review.

DATA COLLECTION AND ANALYSIS

Two authors independently, and in duplicate, assessed the quality of trials and extracted data. Wherever possible, we contacted study authors for additional information. We collected adverse events information from the trials.

MAIN RESULTS

We included nine trials (seven parallel and two cross-over RCTs) with 566 participants. We assessed three trials (33.3%) as having a low risk of bias, four trials (44.5%) at high risk of bias and two trials (22.2%) as having an unclear risk of bias. We only included studies on taste disorders in this review that were either idiopathic, or resulting from zinc deficiency or chronic renal failure.Of these, eight trials with 529 people compared zinc supplements to placebo for patients with taste disorders. The participants in two trials were children and adolescents with respective mean ages of 10 and 11.2 years and the other six trials had adult participants. Out of these eight, two trials assessed the patient reported outcome for improvement in taste acuity using zinc supplements (RR 1.45, 95% CI 1.0 to 2.1; very low quality evidence). We included three trials in the meta-analysis for overall taste improvement (effect size 0.44, 95% CI 0.23 to 0.65; moderate quality evidence). Two other trials described the results as taste acuity improvement and we conducted subgroup analyses due to clinical heterogeneity. One trial described the results as taste recognition improvement for each taste sensation and we analysed this separately. We also analysed one cross-over trial separately using the first half of the results. None of the zinc trials tested taste discrimination. Only one trial tested taste discrimination using acupuncture (effect size 2.80, 95% CI -1.18 to 6.78; low quality evidence).Out of the eight trials using zinc supplementation, four reported adverse events like eczema, nausea, abdominal pain, diarrhoea, constipation, decrease in blood iron, increase in blood alkaline phosphatase, and minor increase in blood triglycerides. No adverse events were reported in the acupuncture trial.None of the included trials could be included in the meta-analysis for health-related quality of life in taste disorder patients.

AUTHORS' CONCLUSIONS

We found very low quality evidence that was insufficient to conclude on the role of zinc supplements to improve taste perception by patients, however we found moderate quality evidence that zinc supplements improve overall taste improvement in patients with zinc deficiency/idiopathic taste disorders. We also found low quality evidence that zinc supplements improve taste acuity in zinc deficient/idiopathic taste disorders and very low quality evidence for taste recognition improvement in children with taste disorders secondary to chronic renal failure. We did not find any evidence to conclude the role of zinc supplements for improving taste discrimination, or any evidence addressing health-related quality of life due to taste disorders.We found low quality evidence that is not sufficient to conclude on the role of acupuncture for improving taste discrimination in cases of idiopathic dysgeusia (distortion of taste) and hypogeusia (reduced ability to taste). We were unable to draw any conclusions regarding the superiority of zinc supplements or acupuncture as none of the trials compared these interventions.

[Time course of changes in gustatory function test results and subjective symptoms, and predictive factors for response in patients with taste disorder receiving 24-week zinc replacement treatment]

In a taste disorder, an agreement between patients' complaints and gustatory function test results is not necessarily found both at the initial hospital visit and during the course of treatment; therefore, it is difficult to assess treatment responses and review treatment strategies based on the assessed treatment responses. The present study investigated the time course of changes in disc gustometry results and subjective symptom scores measured at 4-week intervals in 44 patients with a taste disorder who were considered eligible for zinc replacement treatment and who received polaprezinc at a dose of 150 mg/day (equivalent to a 34 mg/day dose of zinc) for up to 24 weeks. The study also examined the potential differences in treatment outcomes according to the predictive factors for response such as patient background and assessed disc gustometry results during the course of treatment. Results indicated that disc gustometry results and subjective symptom scores showed different time courses of changes. The response rate as measured by disc gustometry was 47.7% at week 12 of treatment, and showed a subsequent slow increase to 56.8% at week 24. On the other hand, subjective symptom scores showed a time-proportional improvement up to week 24. Among the patients included in the present study, a clear difference was found according to the presence or absence of an improving trend as determined by disc gustometry at week 12 of treatment, although there were no differences in ultimate treatment responses, including categories of taste disorder, according to patient background. Patients showing a trend toward improvement had significantly better treatment responses in terms of both ultimate response rates and subjective symptom scores, whereas patients showing no trend toward improvement were less likely to respond to the subsequent 12-week continued treatment.

[The effect of zinc agent in 219 patients with zinc deficiency-inductive/ idiopathic taste disorder: a placebo controlled randomized study]

Diagnosis and treatment of taste disorders are challenging because the disorder can only be determined by the awareness of the patient. Hence, these disorders still require comprehensive evidence. We conducted a randomized, placebo-controlled double-blind study to investigate the effect of polaprezinc, a zinc-containing agent, in 219 patients with either zinc deficiency-inductive or an idiopathic taste, disorder. As a result, the zinc-treated arm experienced a statistically significant improvement against the placebo-treated arm in the perceptible threshold scores of the filter-paper disk method 8 weeks after the administration of the investigational drug. Moreover, the effect lasted for 4 weeks after discontinuation of the drug. However, the effective ratios based on the initial criteria were 55.6% in the treatment group and 43.2% in the placebo, where no statistical significance was recorded. Sex and degree of depression could be two of the potential factors to explain this discrepancy. Furthermore, the effect was not significant among male patients and patients with a high depression score based on the Self-rating Depression Scale (SDS) test. These results indicate that determining the symptom among such patients remains undisclosed. Whereas, in approximately 77%, or 168 patients with "normal" SDS scores and with completely impaired taste qualities, the ratio of effective cases reached 60.9% in the zinc-treated group, the ratio of the placebo-treated group reached 39.5%, resulting in a statistical significance. This may be partly because of a problem in the adaption of male subjects to the gustatory analyses, especially to the identification of saltiness and sourness. Care must also be taken regarding the depressive state of patients when diagnosing and treating taste disorders. Taste disorders caused by depression may not be cured by zinc supplementation due in part to the fact that the symptom is based on a mental issue, and due in part to the conservative responding bias generated by the depression itself, which may inhibit accurate and precise diagnosis of the disorder. In conclusion, administration of a zinc agent is effective for patients with taste disorders, provided selection of appropriate patients is performed, and that proper examination and evaluation are conducted. The present study also indicated that examining depressiveness based on the SDS scores and investigating disturbance of each taste quality using the filter-paper disk method are recommended for the diagnosis and determination of the treatment effect of a taste disorder.

Smell and taste in inflammatory bowel disease

Objective

To investigate the olfactory/gustatory functions of patients with inflammatory bowel disease (IBD) by smell/taste tests, and to determine if disease activity or medication might influence the olfactory/gustatory functions of patients.

Patients and Methods

In total, 59 IBD patients (37 Crohn's disease (CD) and 22 ulcerative colitis (UC) patients) were studied using “Sniffin' sticks” and “taste strips” for olfactory and gustatory tests, respectively, and compared to healthy controls and published normative data.

Results

Among IBD (CD and UC) patients, the values for odor threshold, but not for odor identification or discrimination, were significantly lower than that of the normative data. Further, these patients showed lower values than the normative taste values and the control group for all tastes, except sour; 57.6% of the IBD patients were hyposmic, while 30.5% were hypogeusic. Subjective self-assessments showed that the patients were not aware of their reduced olfactory/gustatory functions. There were no relevant differences in taste and smell abilities between the CD and UC patients. Disease activity and treatment did not influence the olfactory/gustatory functions.

Conclusion

IBD (CD and UC) patients exhibited significant reductions in the olfactory and gustatory functions. Therefore, patients should be tested by smell/taste tests, in order to be adequately informed of their olfactory/gustatory functions and provided an understanding of how to overcome their limitations, and thus improve their quality of life.

Expression and localization of taste receptor genes in the vallate papillae of rats: effect of zinc deficiency

CONCLUSION

We found a difference in expression sites between TAS2Rs and ENaC (epithelial sodium channels). The number of TAS2R-positive cells and ENaC-positive cells were decreased in zinc-deficient diet rats. These findings suggest that decreased expression of taste receptor genes may play an important role in the onset of zinc deficiency-associated taste disorder.

OBJECTIVE

The present study was aimed at histologically investigating the expression and localization of TAS2Rs and ENaC in the vallate taste buds of rats. Changes in expression of the taste receptor genes in zinc-deficient rats were also investigated.

METHODS

The vallate papillae of five rats fed a normal diet and five rats fed a zinc-deficient diet were used. In situ hybridization was performed to investigate the expression and localization of TAS2Rs and ENaC. TAS2R-positive cells per taste bud were counted, and differences in number between the normal and zinc-deficient diet rats were investigated.

RESULTS

In the normal rats, expression of TAS2Rs was observed specifically in the taste bud cells. In contrast, ENaC-positive cells were observed in a part of the taste bud cells and a large number of epithelial cells. Fewer cells were positive for TAS2Rs and ENaC in the zinc-deficient diet rats.

The relationship between zinc intake and serum/plasma zinc concentration in adults: a systematic review and dose–response meta-analysis by the EURRECA Network

Dietary Zn recommendations vary widely across Europe due to the heterogeneity of approaches used by expert panels. Under the EURopean micronutrient RECommendations Aligned (EURRECA) consortium a protocol was designed to systematically review and undertake meta-analyses of research data to create a database that includes ‘best practice’ guidelines which can be used as a resource by future panels when setting micronutrient recommendations. As part of this process, the objective of the present study was to undertake a systematic review and meta-analysis of previously published data describing the relationship between Zn intake and status in adults. Searches were performed of literature published up to February 2010 using MEDLINE, Embase and the Cochrane Library. Data extracted included population characteristics, dose of Zn, duration of study, dietary intake of Zn, and mean concentration of Zn in plasma or serum at the end of the intervention period. An intake–status regression coefficient ($\circ {>\beta }$) was estimated for each individual study, and pooled meta-analysis undertaken. The overall pooled $\circ {>\beta }$ for Zn supplementation on serum/plasma Zn concentrations from randomised controlled trials and observational studies was 0·08 (95 % CI 0·05, 0·11; P < 0·0001; I2 84·5 %). An overall $\circ {>\beta }$ of 0·08 means that for every doubling in Zn intake, the difference in Zn serum or plasma concentration is $2^{ \circ {>\beta }}$ (20·08 = 1·06), which is 6 %. Whether the dose–response relationship, as provided in the present paper, could be used as either qualitative or quantitative evidence to substantiate the daily Zn intake dose necessary to achieve normal or optimal levels of biomarkers for Zn status remains a matter of discussion.

Smell and taste disorders

Smell and taste disorders can markedly affect the quality of life. In recent years we have become much better in the assessment of the ability to smell and taste. In addition, information is now available to say something about the prognosis of individual patients. With regard to therapy there also seems to be low but steady progress. Of special importance for the treatment is the ability of the olfactory epithelium to regenerate.