Effects of vitamin B12 on olfactory functions

Research Article | DOI: https://doi.org/10.31579/2692-9562/061

Effects of vitamin B12 on olfactory functions

  • Ahmet Baki 1*
  • Selçuk Gündoğar 2

1 Başakşehir Çam and Sakura City Hospital, Department of otorhinolaryngology, İstanbul/Turkey
2 Uskudar State Hospital, Department of internal medicine

*Corresponding Author: Ahmet Baki, Başakşehir Çam and Sakura City Hospital, Department of otorhinolaryngology, İstanbul/Turkey.

Citation: Ahmet Baki, Selçuk Gündoğar. (2023). Effects of vitamin B12 on olfactory functions. Journal of Clinical Otorhinolaryngology 5(1); DOI: 10.31579/2692-9562/061

Copyright: © 2023, Ahmet Baki. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received: 09 December 2021 | Accepted: 20 January 2022 | Published: 28 January 2023

Keywords: Vitamin B12; smell test;olfactory function

Abstract

Objective: To evaluate the effects of vitamin B12 on olfactory functions.

Materials and Methods: The smell scores of 48 patients with vitamin B12 deficiency were compared before and after the treatment. The patients followed in the internal medicine were referred to the otolaryngology for the smell test. Smell test was done to the patients before the treatment. After three month of treatment, patients whose vitamin B12 levels reached normal limits were given a smell test.

Results: There were 28 female and 20 male patients in the study. The ages of the patients participating in the study ranged from 24 to 45, and the mean age was 33.9±5.4 years. While the threshold, identification, and total score values of the patients were 2,45±0,5, 3,52±0,5, and 2,98±0,34, respectively, after treatment, 4,7±0,94, 5,32±0,7, and 5,02±0,66. A statistically significant difference was found in the comparison of scores before and after treatment. (p=0.001)

Conclusion: Vitamin B12 treatment provides an improvement in olfactory functions.

Introduction

Olfaction plays an important role in our daily lives, and olfactory dysfunction causes a significant decrease in the quality of life. Approximately 20% of the general population complains about olfactory dysfunction, and 5% of these individuals are anosmic [1]. Psychophysical and electrophysiological tests are often used to evaluate olfaction function. Even though psychophysical tests are generally used for the clinical evaluation of people with smell dysfunction, electrophysiological tests are mostly used for further investigation [2]. The Connecticut Chemosensory Clinical Research Center (CCCRC) olfactory test evaluates the butanol threshold and smell identification [3]. It is validated for the analysis of smell capacity in the Turkish society [4]. It is easy to prepare, cheap, and simple to administer [4]. Because vitamin B12 is not produced in the body, it must be taken from the diet [5]. Vitamin B12 deficiency may be due to insufficient intake, as in vegetarians; however, malabsorption is an essential factor for deficiency [5]. The relation of vitamin B12 deficiency to neurological symptoms has been shown for a long time [5]. Subacute combined degeneration of the spinal cord is the best manifestation of the neurological findings of vitamin B12 deficiency. The dorsal and lateral columns of the spinal cord are affected in this disease. In the case of vitamin B12 deficiency, neurological symptoms such as paresthesia, sensory ataxia, fatigue in the lower extremities, dementia, and optic atrophy can be seen. Rarely, extrapyramidal symptoms such as cerebellar ataxia, dystonia, and chorea may also be seen [6]. Previous studies showed that vitamin B12 deficiency might lead to deficiency in olfactory functions [7]. In this study, we aimed to analyze the olfactory function with the CCCRC olfactory test in individuals with isolated vitamin B12 insufficiency and to reveal the changes in the olfactory level after vitamin B12 replacement therapy.

Materials and Methods

This study included 48 patients with vitamin B12 insufficiency was conducted between june and December 2019. The participants were selected from the internal medicine clinic on the basis of their vitamin B12 testing and then referred to the ENT clinic for olfactory testing. A detailed history was taken from all the patients, and a routine ear, nose, and throat examination was also performed. Patients with nasal septum devia- tion, acute or chronic rhinosinusitis, active upper respiratory tract infection, nasal polyposis, history of nasal surgery, allergic rhinitis, smoking, systemic diseases (e.g., diabetes mellitus, hypothyroidism, hypertension, chronic renal failure, and chronic liver failure), neurological diseases, <18>

Smell assestant

The CCCRC test comprises of a butanol threshold and an identification as already reported [4]. It was administered pre- treatment and in the 12th week post-treatment. 

Butanol threshold test 

The participants were given two glass bottles of the same color and uniform view, one of which contained water and the other a dilute concentration of butanol during the test. They were then ordered to close one nostril and place the tip of the first bottle quickly below the other one. The second bottle was then sampled in a similar manner, and the participant had to select which of the bottles contained something other than water. If the selection was incorrect, a more potent concentration of butanol was submitted along with the bottle having only water. Possible scores ranged from 0–9, but scores ≥7 were scored as 7 per the olfactory test protocol. For the final score, the average of both nostril scores was taken. 

Identification test 

Cinnamon, Vicks, chocolate, Turkish coffee, peanut butter, carbonate, soap, and baby powder were added to opaque bot- tles. The ability to sniff out Vicks showed unimpaired trigeminal nerve function, and all the subjects easily recognized it; therefore, it was not added to the final score. Possible scores ranged from 0 to 7. For the final score, the average of both nostril scores was taken. 

Total score 

Scores for the butanol threshold and identification tests were later averaged to reach a total score, which was classified as defined by Cain et al  [9].

Statistics

Statistical Package for the Social Sciences 22 program was used for statistical analysis. The suitability of parameters to normal distribution was evaluated by Shapiro-Wilks test. Descriptive statistical methods (mean and standard deviation) were determined when evaluating the study data. Wilcoxon Signed Rank test was used to evaluate the dependent non-parametric data. One-way Analysis of variance test was used to compare the groups in terms of stages. P<0>

Results

There were 28 female and 20 male patients in the study. The ages of the patients participating in the study ranged from 24 to 45, and the mean age was 33.9±5.4 years. While the threshold, identification, and total score values of the patients were 2,45±0,5, 3,52±0,5, and 2,98±0,34, respectively, after treatment, 4,7±0,94, 5,32±0,7, and 5,02±0,66. A statistically significant difference was found in the comparison of scores before and after treatment. (p=0.001). While before treatment B12 vitamin levels was 139,56±10,8 ng/L after traetment 548,3±29,2 ng/lt. 

                                                                                                  Table 1: Comparison of scores before and after treatment

Discussion

Olfactory dysfunction may occur because of conductive or sensorineural problems. Conductive dysfunction may occur because of nasal pathologies, whereas sensorineural dysfunction may develop owing to the olfactory receptor and subsequent central pathways [10]. This study reports that vitamin B12 insufficiency is associated with smell abnormality. Mean olfactory test scores are significantly increased in people with vitamin B12 insufficiency after a vitamin B12 replacement protocol. The number of patients with anosmia and hyposmia decreased after vitamin B12 replacement therapy. Previous studies have shown that vitamin B12 deficiency affects the central and peripheral nervous system. The most common neurological disorder as a result of vitamin B12 deficiency is peripheral neuropathy. Also is, subacute combined degeneration well-known and common neurological disorder in vitamin B12 deficiency [11]. Acute chorea, cerebral ischemia, infratentorial and supratentorial leukoencephalopathy are rare diseases that occur as a result of vitamin B12 deficiency [12]. It has been shown that olfactory functions improve after B12 deficiency treatment in a very few cases with olfactory dysfunction (13). Our study shows the positive effect of vitamin B12 treatment on olfactory functions. The pathophysiologic mechanisms of vitamin B12 deficiency in the nervous system are unclear. It is claimed to occur as a result of insufficient remethylation of homocysteine to methionine. The pathophysiological mechanisms of vitamin B12 deficiency in the nervous system are unclear. However, insufficient remethylation of homocysteine to methionine and excessive propionyl-CoA formation lead to degenerative conversion of methylmalonyl-coenzyme A (CoA) to succinyl-CoA, resulting in a decrease in the supply of methyl groups [14]. As a result of deteriorated fatty acids and a defect in the methylation of myelin basic protein, the myelin sheath, which is a component of the nervous system synthesis, deteriorates. In addition, increased plasma homocysteine concentrations can have a direct toxic effect on neurons [15]. Another study claimed that olfactory dysfunction was caused by vitamin B12 deficiency and high homocysteine levels leading to myelin damage in the olfactory nerve [16]. It has been shown that the olfactory threshold is positively correlated with the vitamin B12 level [16]. Chronic rhinosinusitis, infectious diseases and trauma are the most important causes of olfactory functions. Healton et al reported that involvement of the nervous system in 40% of patients with vitamin B12 deficiency [17]. 

In addition to neurological, metabolic, and endocrinological diseases, toxic factors and drugs can cause deterioration in olfactory functions [18]. In our study, we performed an smell test on patients with vitamin B12 deficiency.

Conclusion

Vitamin B12 deficiency causes various neurological disorders as well as olfactory dysfunction. Vitamin B12 treatment provides improvement in olfactory functions. Further studies may be needed to add vitamin B12 therapy to the treatment protocol in patients with olfactory disorders.

Compliance with Ethical Standards:

Financial disclosure: There is no financial support.

Conflict of Interest: There is no conflict of interest in this article.

Ethical approval: All procedures performed in studies involving human participants were by the ethical standards of the institutional and national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The study protocol was approved by the ethical research committee of the Zeynep Kamil Women's and Children's Disease Training and Research Hospital in Istanbul, 

Informed consent: Routine informed consent was obtained from all patients before the hospitalization and also inform consent from the individuals of the control group was obtained in the study. There is no support source that requires confirmation. 

References

Clearly Auctoresonline and particularly Psychology and Mental Health Care Journal is dedicated to improving health care services for individuals and populations. The editorial boards' ability to efficiently recognize and share the global importance of health literacy with a variety of stakeholders. Auctoresonline publishing platform can be used to facilitate of optimal client-based services and should be added to health care professionals' repertoire of evidence-based health care resources.

img

Virginia E. Koenig

Journal of Clinical Cardiology and Cardiovascular Intervention The submission and review process was adequate. However I think that the publication total value should have been enlightened in early fases. Thank you for all.

img

Delcio G Silva Junior

Journal of Women Health Care and Issues By the present mail, I want to say thank to you and tour colleagues for facilitating my published article. Specially thank you for the peer review process, support from the editorial office. I appreciate positively the quality of your journal.

img

Ziemlé Clément Méda

Journal of Clinical Research and Reports I would be very delighted to submit my testimonial regarding the reviewer board and the editorial office. The reviewer board were accurate and helpful regarding any modifications for my manuscript. And the editorial office were very helpful and supportive in contacting and monitoring with any update and offering help. It was my pleasure to contribute with your promising Journal and I am looking forward for more collaboration.

img

Mina Sherif Soliman Georgy

We would like to thank the Journal of Thoracic Disease and Cardiothoracic Surgery because of the services they provided us for our articles. The peer-review process was done in a very excellent time manner, and the opinions of the reviewers helped us to improve our manuscript further. The editorial office had an outstanding correspondence with us and guided us in many ways. During a hard time of the pandemic that is affecting every one of us tremendously, the editorial office helped us make everything easier for publishing scientific work. Hope for a more scientific relationship with your Journal.

img

Layla Shojaie

The peer-review process which consisted high quality queries on the paper. I did answer six reviewers’ questions and comments before the paper was accepted. The support from the editorial office is excellent.

img

Sing-yung Wu

Journal of Neuroscience and Neurological Surgery. I had the experience of publishing a research article recently. The whole process was simple from submission to publication. The reviewers made specific and valuable recommendations and corrections that improved the quality of my publication. I strongly recommend this Journal.

img

Orlando Villarreal

Dr. Katarzyna Byczkowska My testimonial covering: "The peer review process is quick and effective. The support from the editorial office is very professional and friendly. Quality of the Clinical Cardiology and Cardiovascular Interventions is scientific and publishes ground-breaking research on cardiology that is useful for other professionals in the field.

img

Katarzyna Byczkowska

Thank you most sincerely, with regard to the support you have given in relation to the reviewing process and the processing of my article entitled "Large Cell Neuroendocrine Carcinoma of The Prostate Gland: A Review and Update" for publication in your esteemed Journal, Journal of Cancer Research and Cellular Therapeutics". The editorial team has been very supportive.

img

Anthony Kodzo-Grey Venyo

Testimony of Journal of Clinical Otorhinolaryngology: work with your Reviews has been a educational and constructive experience. The editorial office were very helpful and supportive. It was a pleasure to contribute to your Journal.

img

Pedro Marques Gomes

Dr. Bernard Terkimbi Utoo, I am happy to publish my scientific work in Journal of Women Health Care and Issues (JWHCI). The manuscript submission was seamless and peer review process was top notch. I was amazed that 4 reviewers worked on the manuscript which made it a highly technical, standard and excellent quality paper. I appreciate the format and consideration for the APC as well as the speed of publication. It is my pleasure to continue with this scientific relationship with the esteem JWHCI.

img

Bernard Terkimbi Utoo

This is an acknowledgment for peer reviewers, editorial board of Journal of Clinical Research and Reports. They show a lot of consideration for us as publishers for our research article “Evaluation of the different factors associated with side effects of COVID-19 vaccination on medical students, Mutah university, Al-Karak, Jordan”, in a very professional and easy way. This journal is one of outstanding medical journal.

img

Prof Sherif W Mansour

Dear Hao Jiang, to Journal of Nutrition and Food Processing We greatly appreciate the efficient, professional and rapid processing of our paper by your team. If there is anything else we should do, please do not hesitate to let us know. On behalf of my co-authors, we would like to express our great appreciation to editor and reviewers.

img

Hao Jiang

As an author who has recently published in the journal "Brain and Neurological Disorders". I am delighted to provide a testimonial on the peer review process, editorial office support, and the overall quality of the journal. The peer review process at Brain and Neurological Disorders is rigorous and meticulous, ensuring that only high-quality, evidence-based research is published. The reviewers are experts in their fields, and their comments and suggestions were constructive and helped improve the quality of my manuscript. The review process was timely and efficient, with clear communication from the editorial office at each stage. The support from the editorial office was exceptional throughout the entire process. The editorial staff was responsive, professional, and always willing to help. They provided valuable guidance on formatting, structure, and ethical considerations, making the submission process seamless. Moreover, they kept me informed about the status of my manuscript and provided timely updates, which made the process less stressful. The journal Brain and Neurological Disorders is of the highest quality, with a strong focus on publishing cutting-edge research in the field of neurology. The articles published in this journal are well-researched, rigorously peer-reviewed, and written by experts in the field. The journal maintains high standards, ensuring that readers are provided with the most up-to-date and reliable information on brain and neurological disorders. In conclusion, I had a wonderful experience publishing in Brain and Neurological Disorders. The peer review process was thorough, the editorial office provided exceptional support, and the journal's quality is second to none. I would highly recommend this journal to any researcher working in the field of neurology and brain disorders.

img

Dr Shiming Tang

Dear Agrippa Hilda, Journal of Neuroscience and Neurological Surgery, Editorial Coordinator, I trust this message finds you well. I want to extend my appreciation for considering my article for publication in your esteemed journal. I am pleased to provide a testimonial regarding the peer review process and the support received from your editorial office. The peer review process for my paper was carried out in a highly professional and thorough manner. The feedback and comments provided by the authors were constructive and very useful in improving the quality of the manuscript. This rigorous assessment process undoubtedly contributes to the high standards maintained by your journal.

img

Raed Mualem

International Journal of Clinical Case Reports and Reviews. I strongly recommend to consider submitting your work to this high-quality journal. The support and availability of the Editorial staff is outstanding and the review process was both efficient and rigorous.

img

Andreas Filippaios

Thank you very much for publishing my Research Article titled “Comparing Treatment Outcome Of Allergic Rhinitis Patients After Using Fluticasone Nasal Spray And Nasal Douching" in the Journal of Clinical Otorhinolaryngology. As Medical Professionals we are immensely benefited from study of various informative Articles and Papers published in this high quality Journal. I look forward to enriching my knowledge by regular study of the Journal and contribute my future work in the field of ENT through the Journal for use by the medical fraternity. The support from the Editorial office was excellent and very prompt. I also welcome the comments received from the readers of my Research Article.

img

Dr Suramya Dhamija

Dear Erica Kelsey, Editorial Coordinator of Cancer Research and Cellular Therapeutics Our team is very satisfied with the processing of our paper by your journal. That was fast, efficient, rigorous, but without unnecessary complications. We appreciated the very short time between the submission of the paper and its publication on line on your site.

img

Bruno Chauffert

I am very glad to say that the peer review process is very successful and fast and support from the Editorial Office. Therefore, I would like to continue our scientific relationship for a long time. And I especially thank you for your kindly attention towards my article. Have a good day!

img

Baheci Selen

"We recently published an article entitled “Influence of beta-Cyclodextrins upon the Degradation of Carbofuran Derivatives under Alkaline Conditions" in the Journal of “Pesticides and Biofertilizers” to show that the cyclodextrins protect the carbamates increasing their half-life time in the presence of basic conditions This will be very helpful to understand carbofuran behaviour in the analytical, agro-environmental and food areas. We greatly appreciated the interaction with the editor and the editorial team; we were particularly well accompanied during the course of the revision process, since all various steps towards publication were short and without delay".

img

Jesus Simal-Gandara

I would like to express my gratitude towards you process of article review and submission. I found this to be very fair and expedient. Your follow up has been excellent. I have many publications in national and international journal and your process has been one of the best so far. Keep up the great work.

img

Douglas Miyazaki

We are grateful for this opportunity to provide a glowing recommendation to the Journal of Psychiatry and Psychotherapy. We found that the editorial team were very supportive, helpful, kept us abreast of timelines and over all very professional in nature. The peer review process was rigorous, efficient and constructive that really enhanced our article submission. The experience with this journal remains one of our best ever and we look forward to providing future submissions in the near future.

img

Dr Griffith

I am very pleased to serve as EBM of the journal, I hope many years of my experience in stem cells can help the journal from one way or another. As we know, stem cells hold great potential for regenerative medicine, which are mostly used to promote the repair response of diseased, dysfunctional or injured tissue using stem cells or their derivatives. I think Stem Cell Research and Therapeutics International is a great platform to publish and share the understanding towards the biology and translational or clinical application of stem cells.

img

Dr Tong Ming Liu

I would like to give my testimony in the support I have got by the peer review process and to support the editorial office where they were of asset to support young author like me to be encouraged to publish their work in your respected journal and globalize and share knowledge across the globe. I really give my great gratitude to your journal and the peer review including the editorial office.

img

Husain Taha Radhi

I am delighted to publish our manuscript entitled "A Perspective on Cocaine Induced Stroke - Its Mechanisms and Management" in the Journal of Neuroscience and Neurological Surgery. The peer review process, support from the editorial office, and quality of the journal are excellent. The manuscripts published are of high quality and of excellent scientific value. I recommend this journal very much to colleagues.

img

S Munshi

Dr.Tania Muñoz, My experience as researcher and author of a review article in The Journal Clinical Cardiology and Interventions has been very enriching and stimulating. The editorial team is excellent, performs its work with absolute responsibility and delivery. They are proactive, dynamic and receptive to all proposals. Supporting at all times the vast universe of authors who choose them as an option for publication. The team of review specialists, members of the editorial board, are brilliant professionals, with remarkable performance in medical research and scientific methodology. Together they form a frontline team that consolidates the JCCI as a magnificent option for the publication and review of high-level medical articles and broad collective interest. I am honored to be able to share my review article and open to receive all your comments.

img

Tania Munoz

“The peer review process of JPMHC is quick and effective. Authors are benefited by good and professional reviewers with huge experience in the field of psychology and mental health. The support from the editorial office is very professional. People to contact to are friendly and happy to help and assist any query authors might have. Quality of the Journal is scientific and publishes ground-breaking research on mental health that is useful for other professionals in the field”.

img

George Varvatsoulias

Dear editorial department: On behalf of our team, I hereby certify the reliability and superiority of the International Journal of Clinical Case Reports and Reviews in the peer review process, editorial support, and journal quality. Firstly, the peer review process of the International Journal of Clinical Case Reports and Reviews is rigorous, fair, transparent, fast, and of high quality. The editorial department invites experts from relevant fields as anonymous reviewers to review all submitted manuscripts. These experts have rich academic backgrounds and experience, and can accurately evaluate the academic quality, originality, and suitability of manuscripts. The editorial department is committed to ensuring the rigor of the peer review process, while also making every effort to ensure a fast review cycle to meet the needs of authors and the academic community. Secondly, the editorial team of the International Journal of Clinical Case Reports and Reviews is composed of a group of senior scholars and professionals with rich experience and professional knowledge in related fields. The editorial department is committed to assisting authors in improving their manuscripts, ensuring their academic accuracy, clarity, and completeness. Editors actively collaborate with authors, providing useful suggestions and feedback to promote the improvement and development of the manuscript. We believe that the support of the editorial department is one of the key factors in ensuring the quality of the journal. Finally, the International Journal of Clinical Case Reports and Reviews is renowned for its high- quality articles and strict academic standards. The editorial department is committed to publishing innovative and academically valuable research results to promote the development and progress of related fields. The International Journal of Clinical Case Reports and Reviews is reasonably priced and ensures excellent service and quality ratio, allowing authors to obtain high-level academic publishing opportunities in an affordable manner. I hereby solemnly declare that the International Journal of Clinical Case Reports and Reviews has a high level of credibility and superiority in terms of peer review process, editorial support, reasonable fees, and journal quality. Sincerely, Rui Tao.

img

Rui Tao

Clinical Cardiology and Cardiovascular Interventions I testity the covering of the peer review process, support from the editorial office, and quality of the journal.

img

Khurram Arshad

Clinical Cardiology and Cardiovascular Interventions, we deeply appreciate the interest shown in our work and its publication. It has been a true pleasure to collaborate with you. The peer review process, as well as the support provided by the editorial office, have been exceptional, and the quality of the journal is very high, which was a determining factor in our decision to publish with you.

img

Gomez Barriga Maria Dolores

The peer reviewers process is quick and effective, the supports from editorial office is excellent, the quality of journal is high. I would like to collabroate with Internatioanl journal of Clinical Case Reports and Reviews journal clinically in the future time.

img

Lin Shaw Chin

Clinical Cardiology and Cardiovascular Interventions, I would like to express my sincerest gratitude for the trust placed in our team for the publication in your journal. It has been a true pleasure to collaborate with you on this project. I am pleased to inform you that both the peer review process and the attention from the editorial coordination have been excellent. Your team has worked with dedication and professionalism to ensure that your publication meets the highest standards of quality. We are confident that this collaboration will result in mutual success, and we are eager to see the fruits of this shared effort.

img

Maria Dolores Gomez Barriga

Dear Dr. Jessica Magne, Editorial Coordinator 0f Clinical Cardiology and Cardiovascular Interventions, I hope this message finds you well. I want to express my utmost gratitude for your excellent work and for the dedication and speed in the publication process of my article titled "Navigating Innovation: Qualitative Insights on Using Technology for Health Education in Acute Coronary Syndrome Patients." I am very satisfied with the peer review process, the support from the editorial office, and the quality of the journal. I hope we can maintain our scientific relationship in the long term.

img

Dr Maria Dolores Gomez Barriga