Claim #1 - Vitamin C megadoses cause kidney stones
In this case, the megadose is defined as over 6,000 mg (or 6 grams) per day. This is perhaps the most prevalent claim about the dangers of too much vitamin C.
Yet even though it is repeated time and time again, there is no solid evidence that this claim is accurate. In fact, there are many studies that show that large doses of ascorbic acid can actually prevent kidney stones from forming.
Claim #2 - Taking a lot of vitamin C and then abruptly stopping will cause rebound scurvy
It is generally thought that our bodies can become conditioned to high vitamin C dosages when taken for a prolonged period of time. With this conditioning the body is thought to use up the vitamin faster than usual, so a deficiency results when the supplementation is stopped. Hence the term rebound scurvy.
This is another common misconception. Only three cases of rebound scurvy have ever been reported - and all three were anecdotal at best. It has also never been seen in megadose clinical trials or in studies where researchers actually tried to induce rebound scurvy.
Still, it is probably easier on your body to gradually taper down the dosage instead of stopping all at once.
Claim #3 - Too much vitamin C can cause headaches, nausea, fatigue and lightheadedness
There is some truth to this, but the vitamin is revealing a problem and is not the problem itself. These symptoms are from the detoxifying effect the vitamin has on our bodies. And, just for the record, not everyone experiences them.
The easiest way to curb these symptoms is to help your body through the detox. A vitamin C flush is a good way to do just that. Or look at other methods of natural body detox. Once the toxins are dealt with, you won't experience these vitamin C side effects anymore.
Vitamin C megadoses can cause gas and diarrhea.
This is completely true and we should be glad that this is the case.
When your body is saturated with as much vitamin C as you can handle, it dumps the excess in your colon for elimination. This results in diarrhea. Gas usually comes first to let us know that we are almost at that saturating point.
These vitamin C side effects make it easy to determine how much our bodies need and is the whole point behind the vitamin C flush.