Vit C Myths

Vitamin C is the best thing for a cold, so most of us believe. But is it? Where did the idea come from that taking mega-doses of vitamin C banishes cold symptoms?

It wasn’t a pearl of wisdom handed down by our enlightened ancestors, because vitamin C was only discovered in the 1930s.

Nor was it the result of convincing controlled patient trials or biochemical studies.

The idea that taking a hefty vitamin C supplement can help you get over a cold is, in short, a myth.

It grew up in the 1970s, when a charismatic American Nobel Prize-winning chemist started championing the use of vitamin C with almost religious zeal.


Dr Linus Pauling wrote a book, Vitamin C and the Common Cold, which encouraged people to take huge 1,000 milligram doses of vitamin C every day.

He believed if you did this, you could avoid catching a cold, or at least reduce cold symptoms and shorten the discomfort, and he convinced a lot of other people of the same thing.


Word spread, and soon it became accepted as fact that vitamin C cures colds. In reality, there was no good evidence for this assumption at all - as has just been unequivocally demonstrated by a team of Australian and Finnish scientists.


The researchers conducted a review of data from 30 studies around the world involving 11,000 people and spanning several decades. The studies looked at the effect of taking daily supplements of at least 200 milligrams of vitamin C.


Pooling together and analysing the information showed there was no evidence that, for the average person, taking extra vitamin C can stop sneezes, coughs and sniffles.
This kind of "meta-analysis" is often more sensitive than a stand-alone study and better able to spot subtle trends.
Professor Harri Hemila, from the Department of Public Health at the University of Helsinki, said: "It doesn't make sense to take vitamin C 365 days a year to lessen the chance of catching a cold."
Only individuals under extreme physical stress, such as marathon runners, skiers and soldiers, were likely to benefit at all, the research found.

They were 50% less likely to catch a cold if they took daily vitamin C supplements.

Colds are caused by a more than 200 different viruses, which vary in the severity of illness they cause. Like all viruses, they are impervious to antibiotics and extremely resilient.

Normal dietary levels of vitamin C are essential to health. Vitamin C is involved in a range of different biological processes in the body, and as the sailors of old knew only too well, a deficiency leads to scurvy.

The vitamin is also a powerful antioxidant that helps to rid the body of free radicals, small groups of destructive atoms which can damage cells and DNA. For this reason it has been suggested that vitamin C might protect against cancer.

But there’s a world of difference between natural doses of vitamin C and the amounts crammed into many supplements.

The recommended daily allowance of vitamin C is 60 milligrams. Just one 220-millilitre glass of orange juice contains around 97 milligrams of the vitamin. Yet many supplements contain hundreds of milligrams, and Dr Pauling advocated taking a whole gram per day.

The new research is published in the latest issue of the Cochrane Library, published by the Cochrane Collaboration, an international organisation that evaluates medical research.


The Cochrane researchers acknowledge that vitamin C supplements, taken alone or with other substances, might have health benefits other than keeping adult colds at bay.

Prof Hemila said he wanted to see more studies on colds in children, and the effect of the vitamin on pneumonia.

"Pauling was overly optimistic, but he wasn’t completely wrong," he said.