Can you really never have enough Vitamin C?

My sister, who has no medical degree whatsoever, espouses the idea that you can never have too much Vitamin C. Any amount you take over the normal recommended dose, she says, will just make its way out of your body.

This isn't actually true.

An overdose of vitamin C, at the very least, may cause stomach problems - diarrhea, gas, stomach cramps. Sometimes, the effects can be a bit more serious - severe cramps, nausea, and risks for kidney stones. Again, a good way to stay fit is to make this line your mantra: "Anything in excess is bad".

What should be the recommended dose (RDA) for Vitamin C?

Here's the tricky part. Some say that the recommended Vitamin C dose on normal days is 200 - 500 mg for healthy people. For pregnant or lactating women, dose should be lowered to 75-95 mg per day. If you're feeling under the weather, upping the dosage to 1000 mg is fine.

Some, on the other hand, say that people can actually drink up to 25,000 mg of Vitamin C a day without any problems.

The Vitamin C foundation recommends taking at least 3 g of Vit. C a day, and then goes on to say that you should take even more Vit C when you're pregnant (up to 6 grams), and take up to 300,000 mg when you're sick.

This other article tried pushing the limit and said overdosing Vitamin C was fine for him.

It's rather perplexing to note that the RDA for Vitamin C is different, depending on the source and the category of people taking it:

60-95 mg = U.S. Recommended Intake
200 mg = Levin/NIH Recommendation
400 mg = Current Linus Pauling Institute Recommendation
2500 mg = Hickey/Roberts minimum
3000 mg = Vitamin C Foundation's daily recommendation
6000-12000 mg = Levy's daily recommendation
6000-18000 mg = Pauling's daily recommendation
6000-9000 mg = Pregnancy
6000-18000 mg = Heart Disease
14000-30000 mg = Cancer
20000-300000 mg = Cathcart/Levy Cure for Infectious Diseases

So while overdosing seems to be something that is generally not accepted, it seems that the real definition of an overdose in Vitamin C seems to be missing.

Unfortunately, I don't have the final answer to this question either. But, my personal preference would be the 200-500mg (healthy days) to 1000mg (under the weather days) dosage. For one thing, if everyone followed the 6000mg a day dosage, I think we'd be needing more than 1 new Vitamin C factory built everywhere.

How about you guys? How much Vitamin C do you take?