Prophylactic Vitamin C supplements in COVID 19 era -boon or bane: An in vivo study

Introduction

Emergence of COVID-19 infection has led us to realise the importance of good immunity, which is crucial in tackling this pandemic where the availability and efficacy of vaccine is unknown. Concept of immunity boosting has gained a major attention in this pandemic era to strengthen the immunity of the individual where most of the general public have started their own medications ranging from ayurvedic tablets to concoction to vitamin C tablets. Vitamin C is water soluble compound which plays an important role in maintaining the health and immunity of the individual. It acts as co-enzyme for various metabolic reactions, plays pivotal role in collagen synthesis, thus it also contributes to oral health.¹

In this pandemic, it is increasingly prescribed as nonspecific pharmacological treatment for combating the increased inflammatory mediators and to enhance the adaptive immunity of the individual. Chewable vitamin C of 500 mg is most commonly prescribedthrice a day, even for recovery phase of the treatment of COVID19.²

Normal salivary pH ranges from 6.8 - 7.2. Salivary pH reflects the functional integrity of salivary secretion which is controlled by autonomic nervous system.³ Critical pH value for enamel is 5.5. When falls below 5.5, saliva becomes unsaturated with respect to tooth mineral. This is the dissolution point of enamel. On contrary when pH value rises above the critical pH, the saliva becomes supersaturated with respect to calcium and phosphorus ions aiding in remineralisation of damaged tooth structure.⁴

Consumption of chewable vitamin C can lead to drop in salivary pH below 2.3 and drop can be sustained to up to 25 minutes.⁵ Acidic challenge in form of Vitamin C thus lead to dissolution of hydroxyapatite crystals contributing to dental erosion.⁶ Dental erosion is an irreversible tooth wear occurring due to chemical dissolution of tooth without involvement of bacteria. It can occur due to intrinsic or extrinsic causes.

Intrinsic causes are mainly due to exposure to gastric acids which occurs during chronic vomiting or in gastrointestinal disorders. Extrinsic causes are mainly due to consumption of acidic food and beverages.

Microscopically there is loss of prism cores or interprismatic areas initially. On breaching enamel, it affects peritubular followed by intertubular dentine. It is visualised as smooth surfaces clinically and when posteriors are involved there is cupping of occlusal surfaces.⁸

Extent of erosion is partly counteracted by buffering capacity of saliva.⁹ Saliva is complex viscoelastic fluid secreted majorly by three main salivary glands namely parotid, submandibular and sublingual gland and in less quantity by minor salivary glands.It plays a major role in maintenance of integrity of dental tissues such as in cases of erosion.¹⁰

Diabetes mellitus (DM) is an widely prevalentendocrine disease characterized by chronic hyperglycemia. DM has offlate become a public health problem affecting millions of population worldwide. There are two types of DM: type 1 DM and type 2 DM. Type 1DM accounts for approximately only 5% of diagnosed diabetes cases. Impaired salivary gland function is often associated with diabetics due toneuropathy and microvascular dysfunctionleading to decreased salivary production and xerostomia.This hyposalivation effects the buffering capacity of saliva. ¹¹

The aim of this study is to measure and compare the salivary PH drop on ingestion of chewable Vitamin Cin normal healthy individuals and in diabetic patients during this COVID 19 scenario.

Materials and methods

Patient selection:

This study employed 24 subjects - 12 normal healthy individuals (without any comorbidities) and 12 type 2 diabetics(well controlled diabetics). For type II diabetic participants an equivalent number of healthy age-matched controls (range of 30– 60) participants were employed. Consent form was obtained from each patient. Ethical clearance and approval was obtained from the institutional ethical committee.The study was carried out in Government dental college and research institute, Bangalore.

Sample size:

Sample size of 24 subjects (12 in each group) would yield 90% power to detect significant differences, with effect size of 0.25 and significance level at 0.05.

Subjects are divided in to two groups(12 per group) :

GROUP I: Normal healthy individuals

GROUP II:Type 2 diabetics

Saliva collection and measurement of PH:

Saliva collection was undertaken between 8:00 and 10:00 a.m. Participants of both the groups were instructed to be in a fasting state. This is because consumption of food and beverages can alter the resting salivary pHof the individual. Resting salivary pH is measured for both Group I and Group II subjects by collecting 2ml of unstimulated saliva by spitting method in falcon tubes.

Following this, Chewable vitamin C of 500 mg is given to both the groups. Average chewing time is noted to be 3-5 minutes. 2 ml of unstimulated salivary samples are collected at intervals of 15, 30 and 45 min after consumption of 500 mg vitamin C for both the groups. Salivary pH is measured using pH litmus paper and confirmed with digital pH meter

Statistical analysis:

SPSS (Statistical Package For Social Sciences)version 20. [IBM SPASS statistics (IBM corp. Armonk, NY, USA released 2011)] was used to perform the statistical analysis. Inferential statistics like Independent sample t test was be applied to check the statistical difference of salivary pHbetween the groups.Repeated measures ANOVA was applied to compare the statistical difference of salivary pH within the group and post hoc Bonferroni test was used for pair wise comparison.The level of significance was set at 5%

Results

Table 1 shows the comparison of mean pH between the groups at different time intervals. Mean pH was higher in Group I at all the time intervals (figure 1) - 7.17 0.131(at baseline), 6.21 0.084(15 min), 6.38 0.062 (30 min), 7 0.185 (45 min). Unpaired t test was applied to compare the pH between the groups at different time intervals. Unpaired t test showed statistical significant difference between the groups at all the time intervals (p=0.00).

Table 2 shows the comparison of salivary pH within the group for different time intervals using repeated measures ANOVA. Statistical significant difference was seen with each group for all the time intervals (p=0.00).

Post hoc Bonferroni test (Table 3) was applied to compare the mean pH within the group between two different time intervals. Statistically significant difference was seen between all the time intervals (p ≤ 0.05).

Discussion

There is increased consumption of chewable vitamin C among the general population in this COVID 19 situation as self medication for enhancing immunity. It’s easily availability over the counter has led to further upsurge in it’s usage. Knowledge about its deleterious effect on the dental hard tissues is often given a less importance. Dental erosion can occur as potential adverse effect of increased consumption of chewable Vitamin C which can lead to sensitivity of teeth and if not intervened leads to catastrophic damage of the dental hard tissues. ¹²

Chewable vitamin C is also prescribed as nonspecific treatment and as immunity booster for treatment of COVID 19 patients. In order to avert the possibility of acquiring COVID 19 infection, its frequency of usage among the general population has also been peaked up which can contribute to dental erosion. However, buffering capacity of saliva partly counteracts the adverse effects of vitamin C. ^13,14

Impaired salivary secretion is often associated with diabetics who are at increased risk of developing complications associated with COVID 19.¹⁵Decreased salivary flow rate in diabetics is associated with hyperglycemia, glucosuria and greater excretion of body fluids, which can subsequently reduce saliva secretion.16So this study was done to compare the effect of chewable vitamin C on drop in salivary pH in normal healthy individuals and in diabetics and to correlate the same with erosive effects on tooth.

The results of this study show that there is definite pH drop after consumption of chewable Vitamin C. However duration and extent of pH drop varies between the normal healthy individuals and diabetic individuals. Resting salivary pH of normal healthy individuals was 7.17  0.131,whereas in diabetics it was 6.27 0.110(Table 1).

The pH drop after consumption of vitamin C in normal healthy individuals after 15, 30, 45 minutes are 6.21  0.084, 6.38  0.062, 7  0.185 respectively. The results indicate that even after the duration of 30 minutes, the pH failed to return to the normal resting salivary pH. However due to good buffering capacity of saliva in healthy individuals, the drop in pH is not below the critical pH. This particular fact emphasises the important role of saliva in maintaining the tooth integrity.¹⁷

The pH drop after consumption of vitamin C in diabetic individuals after 15, 30, 45 minutes are 5.270.109, 5.45  0.045, 6.11  0.100 respectively. The results indicate that pH drop is more than in Group I, which is statistically significant.The drop in pH is below the critical pH of enamel which is 5.5 and the drop in pH did not return to their resting salivary pH even after the duration of 30 minutes. After 30 minutes the pH slowly began to rise to resting salivary pH.

When the pH falls below critical pH of 5.5, it lead to dissolution of the enamel and dentin microstructure contributing to dental erosion. With increased frequency of consumption of chewable vitamin C, acidic challenge to the tooth increases which enhances the severity of dental erosion. Condition of dental erosion can lead to sensitivity and in severe cases in can contribute to pulpal exposure and if unchecked can lead to catastrophic fracture of the tooth.¹⁸

The drop of pH in diabetics is mainly due to the impairment of normal salivary flow. It could be because salivary secretion is purely under neural control and diabetes affects nerves primarily.¹⁹ Additionally, there can be pathologic changes in the structure of salivary glands due to microvascular disorderin diabetics which can disrupt the production of saliva. The duration of pH drop below critical pH is about 30 minutes. Hence they are more prone for acid attack and greater amount of erosion compared to normal healthy individuals.

A recent study has shown that Vitamin C(500 mg) twice a day mitigates the inflammatory status by lowering the levels of inflammatory mediators like IL-6 and Creactive protein in diabetic and/or hypertensive patients displaying beneficial effects in COVID 19 as well.²⁰ All these factors have enhanced the usage of vitamin C in this pandemic. Moreover normal individuals are prophylactically consuming chewable vitamin C at increased frequencies without appropriate dosage which can again lead to detrimental effect on dental hard tissues.²¹

Majority of symptomatic patients affected by COVID 19 are usually diabetics and/or hypertensives.²² Due to impaired salivary flow, on consumption of chewable vitamin C the drop in salivary pH falls below critical pH and it is not buffered immediately to normal resting salivary pH. This fact accentuates the erosive action of vitamin C on dental hard tissues in diabetics.

This study gives the insight about the deleterious effect of upsurged usage of chewable vitamin C on the salivary PH and erosive effect on the dental hard tissues. Alternative modes of administration of vitamin C that augments its benefits without having any detrimental effects on the dental hard tissues has to be given importance especially in this pandemic era, where in there is excessive consumption of chewable vitamin C for its beneficial effects.

Conclusion

The results of the study indicate that salivary pH drop in diabetics is greater than that of normal healthy individual sand drop is below critical pH of enamel for about 30 minutes which can significantly contribute to dental carious lesions. In this COVID-19 era, there is increased consumption of chewable vitamin C as nonspecific line of treatment. It enhances the immunity of the patient, but its detrimental effects on dental hard tissues is not considered. Guidelines should thus also consider the adverse effects of chewable vitamin C on dental hard tissues and advocate alternate method of intake of vitamin C to maximise its benefits and at the same time maintaining integrity of dental hard tissues.