2018
Li Ran, Wenli Zhao, Jingxia Wang, Hongwu Wang, Ye Zhao, Yiider Tseng, and Huaien Bu

 

Abstract

Aim. To investigate whether vitamin C is effective in the treatment of the common cold.

Method. After systematically searching the National Library of Medicine (PubMed), Cochrane Library, Elsevier, China National Knowledge Infrastructure (CNKI), VIP databases, and WANFANG databases, 9 randomized placebo-controlled trials were included in our meta-analysis in RevMan 5.3 software, all of which were in English.

Results. In the evaluation of vitamin C, administration of extra therapeutic doses at the onset of cold despite routine supplementation was found to help reduce its duration (mean difference (MD) = -0.56, 95% confidence interval (CI) [-1.03, -0.10], and P = 0.02), shorten the time of confinement indoors (MD = -0.41, 95% CI [-0.62, -0.19], and P = 0.0002), and relieve the symptoms associated with it, including chest pain (MD = -0.40, 95% CI [-0.77, -0.03], and P = 0.03), fever (MD = -0.45, 95% CI [-0.78, -0.11], and P = 0.009), and chills (MD = -0.36, 95% CI [-0.65, -0.07], and P = 0.01).

Conclusions. Extra doses of vitamin C could benefit some patients who contract the common cold despite taking daily vitamin C supplements.

 

Introduction

The common cold, known simply as a cold, is defined as an upper respiratory tract infection (URTI) caused by various viruses, characterized by symptoms like coughing or sneezing, sore throat, stuffy or runny nose, headache, fever, muscle aches or aching limbs, and so on [1, 2]. However, because of similar symptoms, there is no way of distinguishing among the different types of common cold, other URTIs, and influenza in most cases.

With regard to virology and pathophysiology, URTIs are a group of diseases in the broad sense, including common cold, viral pharyngitis, laryngitis, herpangina, pharyngoconjunctival fever, and bacterial pharyngotonsillitis, rather than a single diagnosable disease [3].

About 70–80% of URTIs are caused by viruses, like rhinovirus, coronavirus, adenovirus, influenza and parainfluenza virus, respiratory syncytial virus, influenza A virus, and Coxsackie virus, and the other 20–30% are caused by bacteria [2, 4, 5].

Influenza is caused by the influenza virus, three subtypes of which affect humans (influenza viruses A, B, and C [6]); 30–80% of the cases of common cold have been attributed to over 200 strains of rhinoviruses [7, 8]. Influenza is highly contagious, with serious systemic symptoms and mild respiratory symptoms; its peak prevalence is in winter and spring; there are also global outbreaks and epidemics periodically [9–12].

As a frequently occurring acute upper respiratory tract disease, the common cold is self-limiting and generally lasts for 7–10 days or no more than 3 weeks [4]. The onset of the common cold is more acute, usually with nasal catarrh in the early stage. The common cold occurs in patients with low immunity, and the onset is seen year-round but more often in autumn, winter, and spring.

The reason for the seasonality has not been conclusively determined. Further, people under great psychological stress [14] or undergoing intense training have a higher tendency to develop common colds [15, 16]. There are some reports stating that adults contract approximately 2 to 5 infections per year [17]; meanwhile, children develop common colds 6–10 times annually (up to 12 times among school children) [18].

The common cold does little harm on its own; however, it can be a serious complication when other diseases like pneumonia or meningitis develop comorbidly [19]. Despite rapid developments in science and medical technology, the common cold continues to pose a heavy burden worldwide, whether on human health or on economic losses.

Fendrick AM et al. [20] reported that the economic burden attributed to the common cold in the US alone is US $40 billion annually (95% confidence interval (CI), $31.2–$48.0 billion).

According to the data of the World Health Organization (WHO) from 2013, in America, the common cold accounted for 75–100 million physician visits per year at a conservative cost of US $7.7 billion per year, of which US $2.9 billion were for over-the-counter drugs and US $400 million were for prescription medicines.

Additionally, an estimated 22 to 189 million school days were missed because of common colds, leading to 126 million missed workdays to look after children at home [21].

Because no effective therapies exist, treatment for the common cold is based on the relief of symptoms, including cough, sneezing, headache, fever, sore throat, and nasal congestion [21].

Current conventional symptomatic therapies are as follows: nasal decongestants; antihistamines (common cold may lead to a transient bronchial hypersensitivity; thus antihistamines are used); cough suppressants; nonsteroidal antipyretic analgesics, like aspirin; and expectorants.

Additionally, identified in the early 1900s, in the search for the etiology of scurvy [22], vitamin C has been widely utilized in the prevention and treatment of the common cold or URTIs, with conflicting results with respect to its prophylactic effect.

Some evidence has indicated that vitamin C could decrease the incidence of common cold and the duration of symptoms if taken regularly. Pitt et al. [23] found a reduction in the incidence of the common cold or associated morbidity among US Marines who were restricted to 2 g/day of vitamin C.

In Constantini’s study [24], vitamin C halved the duration of URTI episodes in male swimmers. More than 1 g/day of vitamin C shortened the duration of colds in adults by 8% and in children by 18% [25–28].

Inspired by the above-mentioned data, we conducted this meta-analysis to show whether vitamin C could be used for relieving symptoms, shortening the duration, or reducing the incidence of the common cold.

 

Conclusion

The combination of supplemental and therapeutic doses of vitamin C is capable of relieving chest pain, fever, and chills, as well as shortening the time of confinement indoors and mean duration.