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Year : 2020  |  Volume : 9  |  Issue : 3  |  Page : 172-177

Effect of different types of tea on salivary pH - An in vitro study

Department of Oral and Maxillofacial Pathology, Adhiparasakthi Dental College and Hospital, Melmaruvathur, Tamilnadu, India

Date of Submission09-Mar-2020
Date of Acceptance26-Aug-2020
Date of Web Publication30-Sep-2020

Correspondence Address:
Dr. V Saranya
Department of Oral and Maxillofacial Pathology, Adhiparasakthi Dental College and Hospital, Melmaruvathur - 603 319, Tamil Nadu
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Source of Support: None, Conflict of Interest: None


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Saliva has been reported as an important diagnostic tool in many oral and general diseases and is also a main predisposing factor in the development of dental caries. The mean salivary pH is 6.8 that is liable to change with the intake of certain beverages and tea being one among them. Tea is the second most commonly consumed health drink in the world next to water and several studies have demonstrated the influence of green tea on salivary pH levels. This study has gone a step ahead and examined the role of different tea products on salivary pH levels.
Aim: The study aimed to compare and evaluate the effect of three different commercially available tea infusions (Green tea, Lemon tea, Ginger tea) on salivary pH by adopting an in vitro methodology.
Materials and Methods: A total of 30 healthy female subjects were randomly selected between 18 and 25 years of age. Commercially available tea products such as green tea, lemon tea, and ginger tea were used in the study. Portable digital pH meter was used for measuring the pH at baseline and at regular intervals after the consumption of tea (immediately, 5 min and 10 min). The results obtained were statistically analyzed.
Results: In vitro pH readings of saliva after consumption of the three varieties of tea showed pH values of green tea as 7.033 ± 0.26, lemon tea as 7.0026 ± 0.26, and the ginger tea as 7.1818 ± 0.0.24. Thus, the clinical trial showed a statistically significant rise in salivary pH after green tea consumption followed by ginger tea, whereas lemon tea showed a drop in salivary pH after its consumption.
Conclusion: The results revealed that there has been a rise in the salivary pH after the consumption of green tea and ginger tea and hence it adds value to the body of research that consumption of green and ginger tea respectively confers beneficial effects by providing a favorable environment in the oral cavity.

Keywords: Catechins, salivary pH, tea

How to cite this article:
Ravikumar S S, Devika K V, Saranya V, Vasupradha G, Dhivya K, Dinakaran J. Effect of different types of tea on salivary pH - An in vitro study. J NTR Univ Health Sci 2020;9:172-7

How to cite this URL:
Ravikumar S S, Devika K V, Saranya V, Vasupradha G, Dhivya K, Dinakaran J. Effect of different types of tea on salivary pH - An in vitro study. J NTR Univ Health Sci [serial online] 2020 [cited 2021 May 12];9:172-7. Available from: https://www.jdrntruhs.org/text.asp?2020/9/3/172/296828

  Introduction Top

In recent years, there has been an upsurge in the consumption of tea among the world population, and India ranks second in the production of tea and fourth in the exportation of tea.[1] Tea which is produced from the leaves of Camellia sinensis [Figure 1] is the second most commonly consumed healthy beverage after water globally. Green, black, and oolong are the varieties of tea, the classification of which is based upon the fermentation and processing of the leaves.[2],[3] The screening of tea leaves is reported to contain nearly 4000 bioactive compounds, of which the important ones are catechins, polyphenols, flavonoids, alkaloids, tannins, volatile constituents, amino acids, and minerals. Polyphenols contribute to one-third of the bioactive compounds in the tea.[2],[3]
Figure 1: Camelia sinensis leaves

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Saliva is certainly the most powerful and an integral component that aids in maintaining oral health. Various protective functions of saliva against caries include its buffering capacity and flushing of microorganisms from the oral surfaces. The role of saliva in dental health has been widely studied and reported as its pH is etiologically proposed to play a role in the development of dental caries. pH indicates the hydrogen ion concentration which determines whether the solution is acidic or alkaline. The average pH of saliva at rest is about 6.8 and ranges between 6.5 and 7.4. Alteration of salivary pH has been widely studied and are liable to get altered with the intake of certain beverages.[4]

Many studies have demonstrated the influence of green tea on salivary pH, but the effect of most commonly preferred flavors like ginger tea and lemon tea has not been studied adequately.[5],[6] Hence, this proposes to bridge this gap to the extent possible and the purpose of this study is to evaluate and compare the effect on salivary pH before and after consumption of green tea, lemon tea, and ginger tea infusions [commercially available tea bags].

  Materials and Methods Top

A total of 30 healthy female subjects aged between 18 and 25 years studying in our institution and residing in the hostel were randomly selected. A criterion applied for the selection of the participants related to the condition was that they should have been practicing and maintaining good oral hygiene. The study group participants were the same with respect to dietary habits and lifestyle factors. Subjects with systemic diseases and those who were on medications were excluded. Students who were aged below 18 years and above 25 years were also excluded from the study.

Ethical clearance obtained on 11.2.2019 IRB number - 2019/IRB-FEB-OP12/APDCH. Before commencement of the study each one of the participants was explained regarding the purpose of the study and the methodology being adopted in detail and an informed consent was obtained. The tea products used in the study were commercially available green tea, black tea with lemon, black tea with ginger. By adhering to the instructions of the manufacturers, each tea bag was dipped in 120 mL of boiling water and made to brew for 2 min to prepare tea [Figure 2].
Figure 2: Brewed tea

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The study group included a total of thirty randomly selected individuals. For the purpose of statistical analysis, the participants were referred to as Group A, B, and C based on the consumption of different types of tea. Group A (all 30 students) were given green tea for five consecutive days, Group B (same 30 students) were given lemon tea for the next 5 days and Group C (same 30 students) were given ginger tea for five days. Thus, all the 30 participants were subjected to all three varieties of tea and the salivary pH was measured. A resting period of five days was given in between consumption of each type of tea product.

Every day morning, 15 min after brushing, the participants were requested to collect their saliva (unstimulated) into a sterile container by spitting method. 30 ml of the measured tea product was given to the study participants and they were advised to collect their saliva immediately, 5 min, and 10 min after consumption of the tea. The pH of saliva was measured using digital pH meter (Aqua sol handheld Digital pH meter, [Figure 3] and the values were recorded. The pH meter was standardized every day before the study using a buffer capsule according to the manufacturer's instructions. Data were analyzed with SPSS software using ANOVA and Repeated measure ANOVA test. Post hoc Tukey's test was done to confirm the findings and a P value of <0.05 was considered statistically significant.
Figure 3: Aquasol pH meter

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  Results Top

The results were analyzed and tabulated. [Table 1] shows the mean salivary pH levels for 30 study participants before and after consumption of three variety of tea products on five consecutive days. The average baseline salivary pH of the thirty participants before the consumption of tea products was 7.033. The means of the salivary pH immediately, 5 min, and 10 min after the intake of green tea were 7.322 ± 0.30, 7.1412 ± 0.30 and 7.0586 ± 0.25 respectively [Graph 1]. Mean salivary pH immediately, 5 min and 10 min after intake of lemon tea were 7.0026 ± 0.26, 6.9052 ± 0.42 and 6.9492 ± 0.22, respectively [Graph 2]. Mean salivary pH immediately, 5 min and 10 min after the intake of ginger tea were 7.1818 ± 0.0.24, 7.1818 ± 0.24 and 6.9754 ± 0.21, respectively [Graph 3]. [Table 2] shows the mean salivary pH levels of different time intervals of all three tea products on all five days.
Table 1: Anova Test Showing Salivary PH at Different Time Intervals Of Three Different Types of Tea on Five Consecutive Days

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Table 2: The Mean PH of Saliva Before and After Intake of Green Tea, Lemon Tea and Ginger Tea

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Green tea led to a statistically significant (P < 0.05) rise in salivary pH immediately after the intake of tea, which remained above the baseline salivary pH level over the whole period of 10 min. Lemon tea led to a statistically significant (P < 0.05) fall in the salivary pH immediately after the intake of tea thereafter up to 10 min. Ginger tea led to a statistically significant (P < 0.05) rise in salivary pH immediately after intake of tea and the pH dropped back to normal within 10 min. When the three types of tea were compared, the result showed that green tea showed a significant increase in salivary pH followed by ginger tea, whereas lemon tea showed a mild drop in salivary pH after the intake of tea.

  Discussion Top

A crucial component in the oral cavity is saliva, a dilute aqueous solution made up of 99% percent of water along with inorganic and organic constituents.[7] The daily salivary secretion is 750-1000 ml of which submandibular glands account for 60%, parotid for about 30% and sublingual glands for 5% or less and 7% for minor salivary glands. pH of the saliva ranges between 6.7-7.3 in the oral cavity and always maintains neutrality with two mechanisms. First, the flow of saliva removes carbohydrates which can be metabolized by bacteria and thereby reducing the production of acids. Secondly, due to the buffering activity of saliva, acidity from food and beverages, as well as from bacterial activity, is neutralized.[8]

A special interest has been shown to herbal extracts in recent years owing to the antioxidant property in eliminating the free radicals damaging the DNA. Tea is one such healthy beverage with a rich source of antioxidants and numerous added health benefits. These days people prefer tea products incorporated with flavors such as ginger, lemon, mint, cardamom, lemongrass, chamomile etc., Hence, in this study we chose to compare the effects of green tea, ginger tea, and lemon tea on salivary pH. Ginger (Zingiber officinale) belonging to the family Zingiberaceae is a good anti-inflammatory, analgesic, antiemetic, and antioxidant. The phenolic compound gingerol was found to be the active component in ginger. In the oral cavity, ginger increases the salivary flow rate, and inhibits the growth of streptococci.[9] Lemon (Citrus limonum) belongs to the family of Rutaceae contains polyphenols and ascorbic acid and is a natural reservoir of various bioactive chemicals that act as a natural antioxidant.[10],[11] Green tea contains an important component, catechin - epicatechin (EC), epigallocatechin (EGC), epicatechin-3-gallate (ECG), and epigallocatechin-3-gallate (EGCG), among which EGCG is the most abundant catechin which confers the health benefits of consuming tea.[3] It is evident from numerous researches that green tea has anti-carcinogenic, anti-inflammatory, antioxidant, and antimicrobial properties.[12],[13]

In our study, a clinical trial was performed on 30 study participants to evaluate and record changes in salivary pH immediately, 5 min and 10 min after the consumption of green tea, lemon tea, and ginger tea. On analysis, it was found that the green tea showed a statistically significant increase in salivary pH followed by the ginger tea, whereas, the lemon tea showed a drop in salivary pH after its consumption. The results obtained in our study were similar to the studies performed by Sangameshwar et al (2014),[12] Shalal et al (2017)[13] and Ahmed MA et al.[14] Ikigai et al. in 1993 concluded in his study that high levels of EGCG in the tea have a detrimental effect on the cytoplasmic membrane of the bacteria.[15] Recent reports suggest that the EGCG produces hydrogen peroxide within the lipid bilayer which is responsible for damaging the cytoplasmic membrane of the bacteria.[2]

Xu et al. in his study found that catechins cause suppression of the enzyme enolase and phosphoenolpyruvate (PEP) in the glycolytic pathway and thus leading to a decreased internalization of sugar which results in reduced acid production by Streptococcus mutans.[2],[16] The EGCG inhibits the alpha salivary amylase, a major digestive enzyme secreted by salivary glands by catalyzing the conversion of 1,4 linkages of starch to glucose and maltose. Streptococcus mutans also produces the amylase enzyme, and it has been reported that green tea and black tea reduced the amylase activity of S.mutans shortly after the consumption of tea.[2] The presence of polyphenols and theaflavins present in black tea makes it more effective against amylase than the green tea.[2] Hence based on all these observations, it can be inferred that components in tea particularly EGCG is responsible for the inhibition of the adherence of Streptococcus mutans to the teeth, increasing the salivary pH and also inhibiting the acid production from the bacteria.[3]

During the process of manufacturing of green tea, the fresh tea leaves are steamed which preserves the catechins. When green tea leaves are fermented to produce black tea, these tea catechins are dimerized to theaflavins. Thus, catechins are abundant in green tea and theaflavins in black tea explaining the different biological properties of these two varieties of tea.[17]

In our study, a hike in salivary pH over the whole period of 10 min time interval after green tea consumption could be possible because of the abundance of catechins. The salivary pH levels after black tea consumption in this study were less when compared to green tea which may be because of the low levels of catechins in black tea.[2] The bioactive constituents in ginger (gingerol) is readily absorbable resulting in its reduced bioavailability in saliva and hence in our study, the salivary pH level after consuming ginger tea slowly returned back to the base line pH in 10 min.[18] On the contrary, the salivary pH after the intake of lemon tea was significantly reduced due to the ascorbic acid content and it did not return back to the baseline salivary pH even after 10 min. This could be because of the high titrable acidity of the ascorbic acid in lemon tea which is responsible for prolonging the low pH of saliva in the oral cavity.[19]

  Conclusion Top

The results of the present study prove that the components in certain tea products increase the salivary pH. Since the salivary pH after consumption of green tea was higher compared to ginger and lemon tea, it is certainly worth encouraging to consume green tea which acts as an effective natural means to combat dental caries. Further researches should be carried out in this field to promote the use of herbal products in day to day life. It may add further value to the body of research if the scope of this study is further expanded by evaluating the salivary flow rate and the Streptococcus mutans count after the consumption of tea products.



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  References Top

Das P, Zirmire J. Tea Industry in India: Current trends and future prospective. J Pharmacogn Phytochem 2018;7:407-9.  Back to cited text no. 1
Goenka P, Sarawgi A, Karun V, Nigam AG, Dutta S, Marwah N. Camellia sinensis (Tea): Implications and role in preventing dental decay. Pharmacogn Rev 2013;7:152-6.  Back to cited text no. 2
Reygaert W. An update on the health benefits of green tea. Beverages 2017;3:6.  Back to cited text no. 3
Cunha-Cruz J, Scott J, Rothen M, Mancl L, Lawhorn T, Brossel K, et al. Salivary characteristics and dental caries: Evidence from general dental practices. J Am Dent Assoc 2013;144:e31-40.  Back to cited text no. 4
5Srinidhi PB, Basha S, Kumar PN, Prashant GM, Sushanth VH, Imranulla M. Effect of two different commercially available tea products on salivary pH: A randomized double blinded concurrent parallel study. Dentistry and Medical Research. 2014;2:39-42.  Back to cited text no. 5
de Bocanera ME, de Stisman MA, de Labanda EB, de Gepner AC. Statistical analysis of salivary pH changes after the intake of black tea and yerba mate supplemented with sweeteners. J Oral Sci 1999;41:81-5.  Back to cited text no. 6
Kumar B, Kashyap N, Avinash A, Chevvuri R, Sagar MK, Kumar S. The composition, function and role of saliva in maintaining oral health: A review. Int J Contemp Dent Med Rev 2017;2017. doi: 10.15713/ins.ijcdmr.121.  Back to cited text no. 7
Baliga S, Muglikar S, Kale R. Salivary pH: A diagnostic biomarker. J Indian Soc Periodontol 2013;17:461-5.  Back to cited text no. 8
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Zadeh JB, Kor NM. Physiological and pharmaceutical effects of Ginger (Zingiber officinale Roscoe) as a valuable medicinal plant. Eur J Exp Biol 2014;4:87-90.  Back to cited text no. 9
John S, Monica SJ, Priyadarshini S, Sivaraj C, Arumugam P. Antioxidant and antimicrobial efficacy of lemon (Citrus limonum L.) peel. Int J Pharm Sci Rev Res 2017;46:115-8.  Back to cited text no. 10
Goulas V, Manganaris GA. Exploring the phytochemical content and the antioxidant potential of Citrus fruits grown in Cyprus. Food Chem 2012;131:39-47.  Back to cited text no. 11
Sangameshwar M, Vanishree M, Surekha R, Hunasgi S, Anila K, Manvikar V. Effect of green tea on salivary Ph and Streptococcus mutans count in healthy individuals. Int J Oral Maxillofac Pathol 2014;5:13-6.  Back to cited text no. 12
Shalal P. Effects of black tea on salivary pH and flow rate. Int J Innovative Res Med Sci 2017;2:1272-5.  Back to cited text no. 13
Ahmed MA, Pavani B, Tanzila TL, Thanga GD, Thejaswini B, Viha PC, et al. Effects of green tea and chamomile tea on plaque pH, salivary pH, Streptococcus mutans count. Indian Journal of Pharmaceutical and Biological Research 2017;5:1-3.  Back to cited text no. 14
Ikigai H, Nakae T, Hara Y, Shimamura T. Bactericidal catechins damage the lipid bilayer. Biochim Biophys Acta 1993;1147:132-6.  Back to cited text no. 15
Xu X, Zhou XD, Wu CD. The tea catechin epigallocatechin gallate suppresses cariogenic virulence factors of Streptococcus mutans. Antimicrob Agents Chemother 2011;55:1229-36.  Back to cited text no. 16
Chacko SM, Thambi PT, Kuttan R, Nishigaki I. Beneficial effects of green tea: A literature review. Chin Med 2010;5:13.  Back to cited text no. 17
Singletary K. Ginger: an overview of health benefits. Nutrition Today. 2010;45:171-83.  Back to cited text no. 18
Tenuta LM, Fernandez CE, Brandão AC, Cury JA. Titratable acidity of beverages influences salivary pH recovery. Braz Oral Res 2015;29:1-6.  Back to cited text no. 19


  [Figure 1], [Figure 2], [Figure 3]

  [Table 1], [Table 2]


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