Introduction
The common cold, also known as nasopharyngitis or non-specific upper respiratory infection (URI), is a viral infection and one of the world’s most common respiratory health illnesses, other causes include coronavirus, parainfluenza, and influenza (Eccles et al., 2015; Hemilä, 2017). It is associated with acute morbidity, acute ear infections, acute sinusitis, asthma, and other secondary infections (Heimer, Hart, Martin, & Rubio-Wallace, 2009). In the United States alone, more than one billion cases of the common cold are diagnosed annually (Heimer et al., 2009). Loosely translated, each person experiences about two to six colds every year. Therefore, it is one of the main reasons why people seek health care services and possibly a key driver for the high number of clinic visits reported annually (Heimer et al., 2009).
The common cold has several implications for the social, economic, and political development of many communities. It is a nuisance to daily life and is a recurrent and common cause of morbidity (Braun et al., 2000). Additionally, it has huge financial costs to societies because it has several direct and indirect costs related to health care service provision (Fendrick, Monto, Nightengale, & Sarnes, 2003).
The treatment of the common cold is largely limited to interventions that focus on symptom relief. The most common methods used to manage the condition are based on the administration of pharmacological interventions such as pseudoephedrine and guaifenesin as well as popular marketed herbal supplement vitamin C, including Airborne, and Halls Defense Vitamin C Drops. (Heimer et al., 2009). However, the efficacy of these techniques in the management of common cold symptoms is inconclusive. Particularly, there is no proper understanding regarding the use of nutritional supplements, such as vitamin C, in the management of common cold symptoms. At present, the literature appears to be lacking information about the use of vitamin C for treatment or prophylaxis of the common cold thus leaving practitioners to face the dilemma of how to advise patients regarding its use. The purpose of this paper is to understand the effects of vitamin C supplements have on the frequency and incidence of the common cold. The findings may potentially lead to the development of evidence-based suggestions to manage the common cold.
Search Process for the Articles
A literature search, for primary research reports, was done using search engines EBSCO, CINAHL, The National Library of Medicine (PubMed), and google scholar in June 2018 regarding the efficacy of vitamin C for the prevention and treatment of the common cold. Key terms and phrases were vitamin C AND common cold, ascorbic acid AND common cold, common cold, complimentary AND alternative medicine, and upper respiratory infection. The search period was 1990 – 2018. The review was limited to articles that contained original research, systematic reviews, or meta-analysis. Exclusion criteria were articles in languages other than English, articles that were unpublished, and publication dates of 1990 – 2018. Inclusion criteria were prevention, education, and primary care. From this process, 54 original articles were obtained and 46 were removed based on the inclusion and exclusion criteria.
Synthesis of Findings
Reduction in Common Cold Symptoms
Most of the evidence sampled in this review pointed to a reduction in common cold frequencies, severity, and duration after the administration of vitamin C supplements on selected groups of patients. Ran et al. (2018) authored one of the studies reviewed and reported a reduction in the duration of the common cold because of the administration of vitamin C. The authors also established a shortened indoor time for patients who suffered from the common cold because of the intake of vitamin C supplements (Ran et al., 2018). Overall, the study demonstrated that extra doses of vitamin C were important to patients who took daily doses of the same supplement. These findings mirror those of Hemilä (1999), which also show that vitamin C helps to reduce the duration and severity of common cold infections. However, unlike Ran et al. (2018), Hemilä (1999) opines that there are variations in benefits between children and adults.
Notably, the author argues that children, as opposed to adults, enjoyed the greatest relief of common cold symptoms through vitamin C supplementation (Hemilä, 1999). He also demonstrated that variations in dosages also affected the magnitude of the symptoms. For example, a dosage of more than 2g/day was found to be more effective in alleviating symptoms of common cold compared to one of 1g/day (Hemilä, 1999). The same report acknowledged variations in the alleviation of common cold symptoms, but still supported the view that the administration of vitamin C supplements decreases the duration of episodes and severity of its symptoms (Hemilä, 1999). Unlike the study by Ran et al. (2018), Hemilä (1999) cited the extent of alleviation of common cold symptoms by saying that it reduces the incidence of the condition by up to 23%. Other researchers sampled in this review did not provide an estimate of the same.
The reduction in common cold symptoms through vitamin C supplementation was also reported by Van Straten and Josling (2002) who used 168 respondents to study the effects of vitamin C supplementation on the effects of the common cold. The study demonstrated that respondents who took at least 2g/day of vitamin C supplements were less likely to get a cold (Van Straten & Josling, 2002). Even if they did, they recovered faster than those who did not take the same supplements (Van Straten & Josling, 2002). Based on this finding, the researchers proposed that vitamin C should be used as an agent for reducing the frequency and duration of the common cold (Van Straten & Josling, 2002). This recommendation was made against the backdrop of a high level of satisfaction among the respondents about the efficacy of vitamin C in minimizing the occurrence and severity of common cold during winter (Van Straten & Josling, 2002).
The study by Johnston, Barkyoumb, and Schumacher (2014) also supports the positive effects of vitamin C on the reduction of common cold symptoms. It links the condition with a reduction in physical activity and demonstrates that vitamin C intake helps to improve physical activity levels (Johnston et al., 2014). Stated differently, the study generally pointed to the existence of positive and measurable health advantages associated with vitamin C supplementation (Johnston et al. 2014). The greatest effects were reported among male populations with adequate-to-low vitamin C levels (Johnston et al. 2014). Unlike other studies highlighted in this review, the one by Johnston et al. (2014) was gender-specific in its analysis of the effects of the common cold.
A different study by Hemilä (2013) also highlighted the positive effects of vitamin C on the reduction of common cold symptoms because it suggested that the supplements helped to reduce bronchial hypersensitivity. Unlike other studies highlighted in this review, the investigation by Hemilä (2013) evaluated the impact of vitamin C on common cold-induced asthma and used a small sample size of 79 people. This group of respondents was recruited for the study to participate in three clinical trials. Similarly, unlike the findings of Johnston et al. (2014), those of Hemilä (2013) only applied to men. Although three clinical trials that underscored the review differed in terms of methodological approaches, they all affirmed health benefits in the administration of vitamin C supplements to patients who suffered from the common cold (Johnston et al., 2014). Given the positive relationship between vitamin C supplementation and the alleviation of common cold symptoms, the researchers also emphasized the need to test the administration of vitamin C on an individual basis (Hemilä, 2013). At the same time, they recommended further exploration of the effects of vitamin C on common-cold-induced asthma (Hemilä, 2013).
Limited Effects of Vitamin C
Although the above-mentioned studies report a generally positive effect of vitamin C use on the reduction or minimization of common cold symptoms, some researchers do not share the same confidence. For example, the study by Sasazuki et al. (2006) found no significant reduction in the severity and duration of common cold symptoms through the administration of vitamin C. They reported these findings after investigating how a group of 244 respondents who suffered from atrophic gastritis responded to a randomized controlled trial that provided them with 50 or 500mg of vitamin C supplements (Sasazuki et al., 2006). Although these findings slightly differ with those of Ran et al. (2018), Hemilä (1999), and Van Straten and Josling (2002), they affirm a reduction in the frequency of common cold symptoms based on vitamin C administration. Therefore, unlike other studies highlighted in this review, which explicitly support the efficacies of vitamin C in the reduction of common cold symptoms, this study is implicit when making such claims.
Audera, Patulny, Sander, and Douglas (2001) adopted the same cautious approach in a study that sought to find out the effects of large doses of vitamin C on common cold symptoms. Using a double-blind randomized controlled trial, they reported that doses of vitamin C in excess of 1g/day were insufficient in reducing the duration and frequency of common cold symptoms (Audera et al., 2001). Comparatively, a vitamin C dose, which was less than the recommended intake had a stronger effect in reducing the effects of the common cold (Audera et al., 2001). These findings were developed after testing for the impact of the supplements on 400 adult volunteers who were students and staff of the Australian National University (Audera et al., 2001).
Broadly, the studies highlighted above show that vitamin C is associated with a decline in the frequency and severity of common cold symptoms. Differences in methodologies and research approaches could largely account for variations in the degree of symptomatic relief reported in the papers. However, they support the view that vitamin C leads to a decline in common cold severity and frequency. A summary of the review appears in the appendix section.
Implications for Clinical Practice
All of the articles reviewed above were relevant to the EBP question, which sought to establish whether people who consumed vitamin C supplements experienced fewer symptoms of the common cold. Based on this EBP question, the findings of the study are instrumental to the nursing practice because they help to expand the volume of literature explaining the benefits of vitamin C on the common cold and other ailments. Some of the studies analyzed were also instrumental in understanding the limitations of vitamin C intake. For example, the one by Audera et al. (2001) was instrumental in this regard. Relative to this view, the findings of the article are also integral to the nursing practice because they help in explaining the properties of vitamin C that affect the human immune system (Hemilä, 1994). Collectively, the study’s findings are instrumental in enhancing patient satisfaction, which is deemed to be at the heart of the nursing practice. They also give useful insights regarding how to manage the common cold, which is a common respiratory illness. Therefore, they are useful to the global nursing field.
Based on the above-mentioned facts, future studies should try to determine the extent that vitamin C improves the human immune system. At the same time, there should be a reexamination of the use of large quantities of vitamin C to manage common cold symptoms. Since some of the studies sampled also highlighted varying levels of effectiveness in the alleviation of common cold symptoms (using vitamin C supplementation), future research should explain why there are variations in vitamin C effectiveness when treating the common cold. As proposed by Hemilä (1999), the use of further therapeutic trials could be instrumental in explaining differences in vitamin C effectiveness when treating the common cold.
The findings that emerge from this literature review also have a significant impact on my role as a nursing practitioner because I have experienced (first-hand) the effects of the common cold and seen how it not only affects the quality of my colleagues’ work, but also those of patients who come to the healthcare facility to seek relief. However, my knowledge of common cold management is limited to the administration of generic medications. The findings of this paper provide a deeper insight into the management of the condition because they explain the dietary and nutritional role of vitamin C in the management of the same. This knowledge is not only critical to improving my understanding of the relationship between vitamin C intake but also integral in my comprehension of its benefits because I have only heard of its extensive advantages without a proper understanding of the evidence that supports or negates what I know. Therefore, the use of evidence-based research studies to demystify some of these issues is beneficial to me, not only from a professional point of view but also from a personal point of view.
The only issue of contention I have with the findings that have emerged from this review is their failure to explain the extent of vitamin C efficacy in the alleviation of common cold symptoms because most of them have only affirmed a positive relationship between both variables. Understandably, the variations in efficacy levels could be narrowed down to the type of sample chosen. However, there needs to be a clearer explanation of the types of populations or demographics that could benefit the most from vitamin C intake and why this is so because, in my own nursing experience, I have found that certain population groups tend to respond better to specific treatments, while others do not. This view informs the need for more focused clinical trials to explicitly state and describe variations in vitamin C treatments across different groups of people.
Gaps in Literature
Most of the literature sampled in this study established a relationship between the dependent and independent variables, which were vitamin C intake and common cold symptoms. One gap in the literature that emerges from this analysis is the failure of the study to quantify the extent that these two variables are related. Furthermore, the establishment of a correlation between the two variables does not necessarily mean there is causation. This gap in the literature exists because some of the studies revealed varying levels of common cold symptoms, relative to the consumption of vitamin C supplements. Therefore, there is no quantification of the extent of vitamin C use in the alleviation of common cold symptoms. Another gap in the literature that partly explains this problem is the failure of the research studies to categorize the effects of vitamin C use according to different age groups. This observation stems from the review of selected studies, which showed varying levels of efficacy of vitamin C intake based on population dynamics. For example, the study by Hemilä (1999) showed varying levels of efficacy of vitamin C intake in the alleviation of common cold symptoms among adults and children.
The use of small sample size is also another gap in literature because some of the studies sampled relied on a small sample, which could not be generalized across a large population. For example, the study by Audera et al. (2001) only included 400 participants, while that of Hemilä (2013) used only 79 people. Comparatively the sample size used by Sasazuki et al. (2006) was 439 people. These sample sizes are small relative to the generalizability of the findings across large populations. For example, most of the studies mentioned above do not highlight racial, or age disparities that would make people understand the nature of their sample. Indeed, it would be difficult to understand how a study that only relies on about 400 people could be justifiably used to generalize the effects of vitamin C on common cold symptoms for all adults. In this regard, future research should strive to accommodate a larger sample size to improve the ability to generalize their findings across a larger sample size.
Summary
From the onset of this paper, it was established that the EBP question for this review sought to find out the impact of vitamin C intake on the alleviation of common cold symptoms. The main research question stated, “Do patients who take vitamin C supplements develop common cold more or less often than patients who do not take supplements?” The findings of all the eight articles sampled aligned with the research question. Notably, they affirmed a positive relationship between vitamin C intake and the minimization of common cold symptoms. Significant gaps that emerged from a review of the articles centered on the small sample size used in most of the studies to support their findings and the failure of the articles to show the extent of correlation between the dependent and independent variables. These areas of focus largely explain the direction that future research should follow.
References
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