Are high doses of vitamin C useful?

Chris and Kat discussed this one...

Chris: Linus Pauling, who got the Nobel Prize in Chemistry, used to take mega doses vitamin C and he did live to be in his 90s; but then so do lots of people who don't take mega doses of vitamin C.

People have done clinical trials on this to see if taking vitamin C does translate into better health. The evidence is that, if you are vitamin C deficient and you get scurvy, that's very bad, but you don't need very much vitamin C in order not to get scurvy. Scurvy's incredibly rare in the population now. Warding off scurvy's probably not a good enough reason to take mega doses of vitamin C.

In terms of warding off coughs and colds and things there have been a number of trials and the only one that really showed any major benefit was in Scandinavian cross-country skiers who took big doses of vitamin C. They found that with severe exercise they were at slightly lower risk of catching a virus of some kind if they took the vitamin C compared with when they didn't, probably because if you're exposed to harsh conditions - cold air - your airways are getting very dried out; perhaps the vitamin C helps to ward off the damage to your airways caused by those conditions and therefore reduces the risk of the airways becoming vulnerable to viral attack.

Under normal circumstances, I haven't found any evidence that people are better protected if they take vitamin C.

Kat: There was also a paper, I think, about a year or so ago that showed actually if you take vitamin supplements you're more likely to die.

Chris: There was one showing that for vitamin E. Everyone put themselves on vitamin E thinking, 'because this dissolves in fat perhaps it will reduce the rate at which arteries get clogged up by reducing cholesterol.' When cholesterol is oxidised it's more likely to block up arteries. If you take something that dissolves in fats and hence is close to the cholesterol (vitamin E) perhaps that will stop it. People who are on vitamin E started to have more heart attacks than people who weren't, so not very good news...