Too much of a good thing

Most practical medical websites seem to infer that we can get the bulk of our vitamins from a good diet It's not a pretty sight watching me drink my high dose vitamin C in the morning. I look like a cat spitting out bird feathers. So sweet and sour! After a scientist friend told me the other day she wouldn't be caught dead taking high-dose vitamin C because she had heard that it was carcinogenic, it's made me wonder if I am just putting myself through this unappetising experience for nothing, or indeed that it could be bad for me.

I decide to do an internet search on high-dose vitamin C. I learn that vitamin C acts as an antioxidant. It is essential for the production of collagen, the substance that forms the body's connective tissues. It also helps with the absorption of iron.

I can't find anything alleging that high-dose vitamin C could be carcinogenic, though I find a reference to one report saying that taking too much might be "risky". The worst it can do to you is give you loose bowels, maybe a kidney stone, most agree.

Meanwhile, there's definitely some contention on whether vitamin C is a cure-all for a cold. One institute says it's definitely not worthwhile after cold symptoms have started - but people who have been taking the supplement regularly will benefit.

Another thing which is confusing is how much vitamin C is the recommended dose.

I talk briefly to Clinicians naturopath, Jane Cronin about this - I can't quite limit myself entirely to the internet. I take the Clinicians brand of Hi-Dose Vitamin C which gives me 700mg of Vitamin C ascorbic acid, and 2850mg Vitamin C from sodium ascorbate in my daily teaspoonful. The Ministry of Health says an upper limit would be around 1000mg a day.

Jane says it's perfectly fine to take high-dose vitamin C for the whole of winter, and if it's too much my body will let me know by giving me loose bowels. Lovely.

Vitamin C is also great for when you are under stress, she says. Stress depletes the vitamin C levels stored in your adrenals.

But she says that alleging vitamin C clears up colds is still pretty controversial. Some have said it's useful for viral infections, and vitamin C does build white blood cells which help fight infection, she adds.

Most practical medical websites seem to infer that we can get the bulk of our vitamins from a good diet and have a small additional amount in a supplement. Though I have a weakness for cake, I do eat a vitamin C rich diet - things like spinach, oranges, broccoli, baked potatoes, and tomatoes.

I find an interesting online British health journal called What Doctors Don't Tell You (WDDTY), which seems to be the pet medical website of British journalists. It mutters tantalising things about the perceived risks of vitamin C but I need to buy a subscription to read the article.

Having done all this research, I can only report on what is keeping me well over this winter - I haven't had a cold since April though I've had a few near-runs but held them at bay. Over the past few months I have been taking the high-dose vitamin C and Femme Essentials multivitamin and mineral. After my chat with Jane I am going to move on to a lower-dose vitamin C with flavonoids when I finish my current lot. Flavonoids are usually found with vitamin C in nature, she says. And it tastes nice.

Finally, I consult my GP about vitamin C dosage and she, a very practical woman, says she has never taken it a day in her life, relying on diet to make sure she has enough. Just have a couple of kiwifruit a day, she says. She is not worried about my overdosing on my high-dose vitamin C as it is a water soluble supplement, which will just pass through me if it's not needed. Her medical lecturer used to say it was just very expensive urine, she says.