Whenever we fall ill, the response we usually get from people around us is to quickly take some vitamin C.
This is especially so if the symptoms are of a cold or the flu.
But what is the basis of this quick-fire advice and is it backed up by concrete studies? Is there more to it than just stopping a cold?
The Health Ministry has an info-sheet that explains that vitamin C is a water-soluble vitamin important in forming collagen – the protein that gives structure to bones, cartilage, muscle and blood vessels.
The vitamin also helps maintain capillaries, bones and teeth, and aids in the absorption of iron.
Besides that, vitamin C also performs the powerful function of stabilising free radicals, hence making it an antioxidant.
The ministry recommends 90mg a day in general, while for women, 75mg is the recommended dosage.
Foods rich in vitamin C include mostly fresh fruits and leafy vegetables – from apples and papayas to kale, cabbages and mustard leaves.
Other sources include meat, fish, poultry, eggs and dairy products but these only have trace amounts.
The US National Institutes of Health (NIH), the primary agency of the US government responsible for biomedical and public health research, says that vitamin C is needed to synthesise collagen, L-carnitine and certain neurotransmitters.
It is also crucial in protein metabolisation and is important in helping wounds heal.
Aside from being an anti-oxidant itself, it has been shown to regenerate other antioxidants in the body, including vitamin E.
Due to these facts, vitamin C has a reputation as the first line of defence against infections among lay people.
But humans cannot synthesise this compound. We have to supplement our diet by eating food rich in vitamin C. Thankfully, it is abundant in most plants and some animals.
As an anti-oxidant, it has an important role in human blood plasma – an important element that protects the body from infection and other blood disorders.
It wholly protects plasma lipids against detectable peroxidative damage caused by certain radicals. It is the only plasma antioxidant able to do so.
There is ongoing research on how vitamin C’s antioxidative nature can affect damage to the body caused by free radicals.
These oxidation damages play an important role in major diseases that plague humans today.
Vitamin C’s effect on brain health has also been studied for its use against degenerative mental diseases and ageing.
The conclusion of the 2014 report, however, stated that many studies only show a correlation between the lack of the vitamin and oxidative stress in certain cognition diseases, and not how those vitamins improve the condition.
Another study done the following year showed that ascorbic acid – another name for vitamin C – yielded positive in vitro results when tested as a protective agent in patients for the treatment of neurodegenerative diseases.
The problem lies in how to keep the substance from rapid oxidation during in vivo tests.
In a 2017 study, vitamin C was shown to support skin barrier function against pathogens and promote oxidant scavenging activity at the skin level, which protects against environmental oxidative stress.
It also collects in phagocytic cells, which help kill microbes.
In terms of protection, many large-scale studies on animals show that vitamin C plays a role in preventing, shortening and alleviating diverse infections – an ability reflected in humans.
Controlled studies show that under certain conditions in restricted population subgroups, vitamin C shortens and alleviates the common cold and prevents colds.
Five controlled trials also show significant effects against pneumonia.
While the evidence of vitamin C’s abilities as an effective barrier against common diseases is not as abundant or conclusive for experts to definitively say that it can stave off infections, the ones that do suggest that offer enough promise to warrant more research into this topic.
As a preventive measure, Vitamin C is safe enough to be taken and does not cost too much when taken regularly as a supplement.