Vitamin C and the winter ills

Vitamin C and the winter ills

Will Vitamin C really keep the winter ills away?

The cold weather has hit, the heaters are on, and many of us have reached for the Vitamin C supplements. But will large doses help us keep healthier?

Why the interest in Vitamin C?

One of the reasons the dosage around Vitamin C has been on the radar for some time is that humans, unlike most animals, are unable to synthesize Vitamin C in our bodies. This means we have to find it in our diet.

In the 1970s, Linus Pauling suggested Vitamin C could successfully treat and/or prevent the common cold [1].

Results of subsequent controlled studies have been inconsistent, resulting in confusion and controversy, though public interest in the subject remains high.


So, what is Vitamin C and what does it do?

Vitamin C (also known as L-ascorbic acid) is a water-soluble vitamin. Some of its main roles include:

  • being required for the creation of collagen, some neurotransmitters, and its involvement in protein metabolism
  • assisting in the growth and repair of skin, bones, teeth and other tissues
  • increasing the absorption of iron in the gut from iron-containing foods
    being an essential component in the immune system [2]

The recommended daily intakes for adults are:

  • males 45mg
  • females 45mg

Note: Smokers should have an extra 35mg/day due to increased oxidative stress in the body [3].

Sources of Vitamin C

Vitamin C is primarily found in fruits, vegetables and juice. Below are some examples of fruits and vegetables high in Vitamin C [2].





Breaking the myths

Research that has been completed suggests regular intake of 200mg or more Vitamin C per day:

  • does not prevent the general population from developing the common cold
  • can prevent development of colds in elderly, chronic smokers and people exposed to cold environments and extreme physical exercise
  • may shorten the length of a common cold and decrease symptom severity in the general population through anti-histamine effects [4]

Is it possible to take too much?

There are thought not to be serious adverse effects of high Vitamin C intake because excess amounts are excreted in urine.  However, there have been reports of gastrointestinal reactions to high amounts of Vitamin C such as diarrhoea, nausea and abdominal cramps[4].

Is it possible to have too little?

In essence, yes, but this is unlikely in today’s diet. However, inadequate intake of Vitamin C can lead to scurvy. Until the end of the 18th century, many sailors who went on long sea voyages with foods that did not supply Vitamin C actually died from scurvy. During the mid-1700s, a British Navy surgeon called Sir James Lind conducted experiments and found that eating citrus fruits or juices could cure scurvy. It wasn’t until 1932, however, that scientists showed that the active component preventing scurvy was ascorbic acid [5].


There is support for Vitamin C to be taken while sick for reducing symptoms and the length of the illness. The same amount of Vitamin C can be derived from an orange, a kiwifruit and some capsicum. The benefit of sourcing Vitamin C through foods rather than tablets is that they provide other vitamins, fibre and antioxidants.

Consider switching that Vitamin C pill or capsule for a snack of fruit if you are feeling unwell this winter.


  1. Pauling L. The significance of the evidence about ascorbic acid and the common cold. Proc Natl Acad Sci USA 1971;68:2678-81 (PubMed abstract)
  2. Dietitians of Canada. Food Sources of Vitamin C. 2008. PEN Database
  3. National Health and Medical Research Council Australia. Vitamin C. NHMRC, January 2017.
  4. National Institute of Health. Vitamin C – Fact Sheet for Health Professionals. NIH, March 2018.
  5. King CG, Waugh, W.A. The Chemical nature of vitamin C. Science 1932;75:357-358