Yet dietary supplement sceptics, who remain both numerous and influential in forming conventional medical and scientific opinion, continue to argue that the benefits of vitamin C supplementation are unproven and even that large doses may be dangerous. Of course it's only right and indeed essential that the claims made on behalf of vitamin, mineral and other supplements should be subject to the most rigorous scientific scrutiny, but the public is unlikely to have either the time or the inclination to make a detailed study of the myriads of learned articles and reports that appear in the constantly and rapidly expanding literature. Worse: the media loves nothing more than to hype a modest and moderate contribution to new knowledge as either a miracle cure or horrifying scare story. So as Shakespeare might have said, but didn't: to supplement or not to supplement, that is the question. How in these circumstances is the reasonably intelligent layman to proceed?
As with many questions in life the best answer probably lies in a careful analysis of the likely risk to reward ratio. You can of course apply such an analysis to many aspects of life; to investments, to career decisions; to gambling, perhaps even to personal relationships. But can such a test sensibly be applied to questions of health?
Well, in the case of vitamin C, the argument might be summarised as follows: the benefits are numerous and well established – not perhaps to the criminal standard of proof beyond all reasonable doubt on which the scientific community seems to want to insist, but at least to the standard of balance of probabilities on which most practical decisions in life have to be based.
And these benefits to long-term health are potentially spectacular. Vitamin C is known as a powerful anti-oxidant which is highly effective in protecting against the largely invisible but highly damaging free radical activity that is a major cause of premature ageing and diseases of degeneration. So vitamin C has been repeatedly shown to have potential protective effects against cardiovascular disease, stroke, cataracts, cognitive dysfunction and even certain common cancers, including those of the stomach, oesophagus, colon, bladder,
The risks, by contrast, appear on the balance of probabilities to be negligible. It's true that a small number of recent studies attracted great attention by suggesting that rather than acting as an anti-oxidant vitamin C may actually increase free radical activity. And naturally these were eagerly seized upon and exaggerated both by conservative medical practitioners and the media. The strong consensus of opinion, however, is that these studies were not only flawed in themselves – not being comprised of full peer–reviewed research, but that they are in any case comprehensively outweighed by the numerous reports which demonstrate its many benefits.
In terms of toxicity, vitamin C is water soluble allowing the body easily to excrete any excess, leaving perhaps a transient and relatively minor gastric upset as its only likely ill-effect if consumed in excess of a recommended safe dosage limit of 2,000 mg (2 grams) a day.
Supplements of certain lesser known vitamins and minerals may tend to be costly, but manufactured l-ascorbic acid appears to be chemically indistinguishable from that occurring naturally in fresh fruits and vegetables (which it is still highly advisable to eat in lavish quantities) and effective supplements are therefore readily and inexpensively available.
The authoritative Linus Pauling Institute recommends 400 mg daily intake as a tissue saturation level of vitamin C, and the risks and costs involved in achieving this appear so low when set against the potential long-term health benefits that it appears at the very least to be a wise form of inexpensive health insurance.