The common cold is one of the most common, yet often misunderstood conditions. Its symptoms and duration can vary considerably from person to person, as the common cold is usually caused by several respiratory viruses (rhinovirus, coronavirus, adenovirus, parainfluenza, influenza, respiratory syncytial virus), which together have about 200 serotypes (variants of a virus, which differ from each other based on the structure of their surface molecules, in particular antigens, the latter representing the substances recognized by the immune system, which produces specific antibodies to attack them). The most frequent agent that causes the common cold is rhinovirus, which is found in 30%-50% of affected individuals. Therefore, the term “common cold” does not refer to a single entity, but to a group of diseases caused by numerous etiological agents that are often unrelated to each other.

When you have a cold, taking vitamin C is recommended but in this regard, we might ask ourselves some questions, such as

  • what is the link between vitamin c and cold and its real benefits
  • What is the mechanism of action of Vitamin C on the immune system?
  • What could be the possible side effects of taking Vitamin C?

Questions that we will try to answer, but first let's start by saying that the common cold is often an underestimated problem, that's why it is necessary to talk first about the symptoms and the social impact of the common cold.

SYMPTOMS AND IMPACT OF THE COMMON COLD

 Symptoms such as sneezing, runny nose, nasal congestion, sore throat, and in some cases fever or muscle aches make the common cold a debilitating condition for many people. Despite its benign nature, the common cold can have a significant impact on daily life, causing absences from work and school and considerable healthcare costs, especially in high-income countries.

A common mistake is to resort to antibiotics to treat it (just think that according to some scientific research, in the USA, 50% of patients affected by the common cold have received antibiotics) ignoring that it is almost always, at least initially, caused by viruses, on which antibiotics have no therapeutic effect. This improper use is not only ineffective, but also contributes to the spread of antibiotic resistance, with often very complex and difficult to manage consequences that affect the health not only of the individual but of the entire population of the planet. This is why alternative therapeutic options for the common cold are of considerable interest for public health. Among the possible therapeutic proposals, Vitamin C is often recommended. But what is the reason for the suggestion, what is the link that is generated between Vitamin C and the cold?

CORRELATION BETWEEN VITAMIN C AND COLD

 The history of the link between vitamin C and colds has deep roots and extends over 80 years. It all began with numerous studies conducted on different animal species, which demonstrated that vitamin C could improve the resistance of the living organism to viral and bacterial infections. These results paved the way for scientific research: if vitamin C could exert a protective effect in animals, could it not have the same role in humans?

That's why since the 40s, researchers have been trying to explore and scientifically document the beneficial potential of vitamin C against the common cold. A turning point came in 1971, when scientist Ritzel conducted a randomized placebo-controlled study on children in a ski school. During the study, participants were given 1 gram of vitamin C per day. The results were significant: the incidence of colds was reduced by 45%, while the duration of episodes decreased by 31% in the children who received the treatment.

This discovery aroused the interest of biochemist Linus Pauling and Nobel Prize winner (1954, 1962), who in 1970 published the book “Vitamin C and the Common Cold”. Through his meta-analysis that included Ritzel's study and four other studies (on sample populations composed of adults) all randomized and placebo-controlled, to which he applied various statistical methods (including the Fischer test), Pauling argued that the intake of high doses of vitamin C could significantly reduce the incidence and duration of colds worldwide. The publication had a considerable impact, generating great enthusiasm among the public, but also strong criticism from a large part of the scientific community, which questioned the validity of Pauling's statements, giving rise to a scientific debate for a long time, until today.

THE SCIENTIFIC DEBATE

 Within five years of the publication of Pauling's book, several researchers, including Chalmers, Dykes, and Karlowsky, published studies refuting Pauling's results. Their criticisms focused mainly on two aspects: the amount of vitamin C administered and theeffectiveness real in reducing the incidence of colds. According to these detractors, in fact, the effect of vitamin C was overestimated and not supported by sufficiently solid scientific data.

However, the debate did not stop there. Scientists such as Anderson (1977) and Hemillä (1995, 1996, 2006) supported, at least in part, Pauling's conclusions and through new studies and analyses, demonstrated that some of the criticisms aimed at Pauling's theories were not entirely correct, highlighting that regular intake of vitamin C, especially in doses equal to or slightly above 1 gram per day, could actually alleviate cold symptoms and reduce their duration. Furthermore, they highlighted the presence of a dose-dependent effect: doses equal to or slightly above 2 grams per day offered greater benefits, even if these results were not universally applicable to all sample populations.

RECENT SCIENTIFIC EVIDENCE

 Today, the most recent studies have clarified some important aspects and, above all in relation to the binomial administration REGULAR of Vitamin C and Cold, there remain very few doubts but many certainties, such as…

  • Adults with colds supplemented with vitamin C at doses ≥ 1 g/day consistently showed reduction or attenuation of cold symptoms and severity (fewer days at home), and this benefit was greater if doses just above 2 g/day were administered, although this was not evident in all populations sampled.
  • In adults subjected to ACUTE and SEVERE physical stress, regular vitamin C supplementation halved the incidence and severity of acute respiratory symptoms typical of the common cold; however, if this stress lasted for 2 or 3 months (CHRONIC stress) the beneficial effects of vitamin C were not seen. NOTE: also because in this case there were other and different causes determining the stress.
  • A study of 674 Navy recruits in training found that even though the sample population was subjected to chronic stress, those who had been supplemented with vitamin C for a period of 8 weeks did not develop pneumonia, as did 8 individuals from the population who did not take vitamin C (placebo).
  • Children showed greater benefit during and after regular vitamin C supplementation than adults. Furthermore, even in these particular sample populations, as was the case in adults, supplementation of amounts just above 2 g/day conferred benefits almost double those who took 1 g/day.

These and many other scientific studies have demonstrated the real benefits of vitamin C on colds, both in intensity and severity, also highlighting a dose-dependent effect. But let's see what is the mechanism hypothesized to obtain these benefits, so let's talk about the…

MECHANISM OF ACTION OF VITAMIN C ON THE IMMUNE SYSTEM

 Vitamin C has been the subject of numerous studies that have highlighted its fundamental role in supporting the immune system and mitigating the effects of infections. One of the most relevant aspects concerns the ability of vitamin C to influence key immunological processes, such as phagocytosis, leukocyte chemotaxis, viral replication and interferon production.

ANTIOXIDANT AND IMMUNOMODULATING PROPERTIES

 Vitamin C acts as a powerful water-soluble antioxidant, capable of protecting cells from oxidative stress generated during infections. Oxidative stress, caused by the increase in free radicals, can damage both cellular structures and compromise immune function. Vitamin C, by reducing this stress, helps maintain the integrity and effectiveness of immune cells.

TRANSPORT AND REGENERATION MECHANISM

Phagocytes (leukocytes), key cells of the immune system, possess a specific transport system that allows them to import the oxidized form of vitamin C, dehydroascorbic acid, and convert it into its active, reduced form. This process “requires” a continuous supply of vitamin C, essential to support their immune response.

In summary, vitamin C exerts a multiple and synergistic action in strengthening the immune system, protecting immune cells from oxidative stress and improving their functionality.

But can the administration of high doses (equal to or slightly higher than 2 grams/day) of vitamin C produce unwanted effects in the individual who takes them?

WHAT COULD BE THE POSSIBLE SIDE EFFECTS OF ADMINISTRATION OF VITAMIN C?

 Vitamin C, although generally considered safe, even in high doses, has seen constant reevaluation by the scientific community over the years regarding its impact on the common cold. Studies by Dykes (1975) and Hemillä (2006) confirmed that fears about the side effects of high doses of vitamin C were unfounded, helping to debunk the myth of the dangers of massive supplementation.

KEY FINDINGS:

  • High Dose Safety: Bee (1980) and Cathcart (1981) reported that daily oral doses of 10-15 g or over 30 g did not cause significant adverse effects in healthy subjects.
  • Rare reports of serious side effects: The sporadic cases of serious adverse events are usually related to pre-existing clinical conditions
  • Scientific consensus on safety at 2 g/day: the threshold of 2 grams per day is universally considered safe. Clinical studies, including the most recent ones, have not found risks associated with this dose.

LIPOSOMAL VITAMIN C: AN INNOVATIVE TECHNOLOGY

 

Vitamin C, therefore, is not a miracle cure for the common cold, but it is a valid ally in dealing with it with less discomfort. Whether it is preventing the infection, reducing the duration of symptoms or limiting their spread, this vitamin plays a fundamental role in maintaining our well-being, especially during the colder months.

Among the many supplements on the market, liposomal vitamin C stands out for its effectiveness. Thanks to liposomal technology, the vitamin is enclosed in a phospholipid liposome, which facilitates its absorption. These microspheres formed by lipid layers allow optimal levels of vitamin C to be maintained in the blood, ensuring a more effective therapeutic action.

If you want to be updated on the latest news, sign up for the newsletter