1. Rodak K, Kokot I, Kratz EM. Caffeine as a factor influencing the functioning of the human body-friend or foe? Nutrients 2021;13(9):3088. https://doi.org/10.3390/nu13093088

2. Bdullahi R, Lawal A, Ibrahim M, Khalid A, Muhammad U. Assessment of the level of caffeine in some tea leaves marketed in dutse: Jigawa state. Korean J Food Health Converg 2019;5(3):7-20. https://doi.org/10.13106/kjfhc.2019.vol5.no3.7

3. Knapik JJ, Steelman RA, Trone DW, Farina EK, Lieberman HR. Prevalence of caffeine consumers, daily caffeine consumption, and factors associated with caffeine use among active duty United States military personnel. Nutr J 2022;21(1):22. https://doi.org/10.1186/s12937-022-00774-0

4. Azari S, Aghaz A, Maarefvand M, Ghelichi L, Pashazadeh F, Shavaki YA. The prevalence of voice disorders and the related factors in university professors: a systematic review and meta-analysis. J Voice 2022:S0892-1997(22)00057-1. https://doi.org/10.1016/j.jvoice.2022.02.017

5. Franca MC, Simpson KO, Schuette A. Effects of caffeine on vocal acoustic and aerodynamic measures of adult females. CoDAS 2013;25(3):250-5. https://doi.org/10.1590/s2317-17822013000300010

6. Kahlenberg RD, Potter H. Why teacher voice matters. American Educator. Winter 2014-15. [Accessed on: July 10, 2023]. Available from URL:https://www.aft.org/sites/default/files/kahlenberg.pdf

7. Mahmoud NF, Khaled DMF. Mohammed HO. Knowledge of Egyptian faculty members about voice care: a national cross-sectional study. Egypt J Otolaryngol 2022;38:59. https://doi.org/10.1186/s43163-022-00247-5

8. Kyriakou K, Petinou K, Phinikettos I. Risk factors for voice disorders in university professors in cyprus. J Voice 2018;32(5): 643.e1-643.e9. https://doi.org/10.1016/j.jvoice.2017.07.005

9. Georgalas VL, Kalantzi N, Harpur I, Kenny C. The effects of caffeine on voice: a systematic review. J. Voice. 2023;37(4):636.e7-636.e19. https://doi.org/10.1016/j.jvoice.2021.02.025

10. Bolbol SA, Zalat MM, Hammam RA, Elnakeb NL. Risk factors of voice disorders and impact of vocal hygiene awareness program among teachers in public schools in Egypt. J Voice 2017;31(2):251e.9-251e.16. https://doi.org/10.1016/j.jvoice.2016.07.010

11. Johnson AF, Jacobson B, Grywalski C, Silbergleit A, Jacobson G, Benninger MS. The Voice Handicap Index (VHI). Am J Speech Lang Pathol 1997;6(3):66-70. https://doi.org/10.1044/1058-0360.0603.66

12. Grandjean AC, Reimers KJ, Bannick KE, Haven MC. The effect of caffeinated, non-caffeinated, caloric and non-caloric beverages on hydration. J Am Coll Nutr 2000;19(5):591-600. https://doi.org/10.1080/07315724.2000.10718956.

13. Nehlig A. Interindividual differences in caffeine metabolism and factors driving caffeine consumption. Pharmacological Rev 2018;70(2):384-411. https://doi.org/10.1124/pr.117.014407

14. Byeon H. The risk factors related to voice disorder in teachers: a systematic review and meta-analysis. Int J Environ Res Public Health 2019;16(19):3675. https://doi.org/10.3390/ijerph16193675.

15. Akhtar S, Wood G, Rubin JS, O'Flynn PE, Ratcliffe P. Effect of caffeine on the vocal folds: A pilot study. J Laryngol Otol 1999;113(4):341-5. https://doi.org/10.1017/s0022215100143920

16. Akinbode R, Lam KBH, Ayres JG, Sadhra S. Voice disorders in Nigerian primary school Teachers. Occup Med 2014;64:382–386. https://doi.org/10.1093/occmed/kqu052

17. Levendoski EE, Sivasankar S. Investigating the effects of caffeine on phonation. J Voice 2011;25(5):215-9. https://doi.org/10.1016/j.jvoice.2011.02.009

18. Ahmed EE, Bukhari MA, Melibary RA. Voice disorders among academic staff at king saud university medical college (comparison between basic science and clinical staff). J Otolaryngol ENT Res 2017;8(1):394‒6. https://doi.org/10.15406/joentr.2017.08.00233

19. Moy FM, Hoe VCW, Hairi NN, Chu AHY, Bulgiba A, Koh D. Determinants and effects of voice disorders among secondary school teachers in Peninsular Malaysia using a validated malay version of VHI-10. PLoS One 2015;10(11):e0141963. https://doi.org/10.1371/journal.pone.0141963

20. Dillon P, Kelpin S, Kendler K, Thacker L, Dick D, Svikis D. Gender differences in any-source caffeine and energy drink use and associated adverse health behaviors. J Caffeine Adenosine Res 2019;9(1):12–19. https://doi.org/10.1089/caff.2018.0008

21. Alarouj H, Althekerallah JM, AlAli H, Ebrahim MA. A comparative study utilizing the Voice Handicap Index-10 (VHI-10) in teachers and the general population of Kuwait. J Voice 2022;36(2):289.e1-299.e10. https://doi.org/10.1016/j.jvoice.2020.05.006

22. Flynn H. Can adding milk to a cup of coffee have anti-inflammatory effects? Medical News. [Accessed on: July 3, 2023]. Available from URL: https://www.medicalnewstoday.com/articles/can-adding-milk-to-a-cup-of-coffee-have-anti-inflammatory-effects