The wiki: vitamin C covers almost every angle for anyone trying to examine whether Vitamin C is (a) worth taking as a supplement (b) could be damaging if taken in high doses.
Some questions to answer:
What is the main reason for taking high dose vitamin C?
What is a high dose?
Is natural vitamin C better for you than synthetic?
How does it work and what happens in the body?
For starters, it would appear Vitamin C would not be first choice for a suicide drug:
If you take a lot of Vitamin C you will notice your urine changes colour. This explains why and gives an answer to how much to take:
Nature Medicine ( 7, 29 – 30 (2001) :
Forbidden Fruit: Although citrus fruits prevent and cure scurvy, they may not always be as good for you as you thought.
by J. K. Aronson,
..the body goes to great lengths to avoid excess accumulation of vitamin C, and has at least three ways of accomplishing this. First, absorption of vitamin C from the gut is highly saturable, ensuring that the amount that is absorbed reaches a maximum at relatively low doses. Second, the kidney rapidly excretes vitamin C, because its re-absorption from the renal tubules after filtration by the renal glomerulus is also highly saturable. Virtually all the vitamin C that is absorbed from the gut is thus excreted in the urine. For example, when the daily dose is increased from 200 to 2500 mg (from 1.1 to 14 mmol) the mean steady-state plasma concentration increases only from about 12 to 15 mg/l (from 68 to 85 mol/l)—no matter how high a dose of vitamin C you take orally there is a limit to the plasma concentration that can be reached. Third, tissue uptake is also saturable. An increase in plasma concentration of vitamin C is not associated with a parallel increase in tissue concentration11. Indeed, the tissue vitamin C concentration, measured in leukocytes, saturates at 100 mg daily4 or plasma concentrations of 14 mg/l (80 mol/l)(ref. 11).
So no matter how much you take, all you do is increase the concentrations in your urine and gut, and that can cause adverse effects12. Vitamin C is partly excreted as oxalate, and very high doses can lead to hyperoxaluria and kidney stones13, particularly after intravenous use and in people with renal insufficiency. Adverse effects in the gut include nausea, abdominal cramps and diarrhea14.
He provides a table of grapefruit drug interractions. Most people taking these drugs are warned on the packet.
From wiki: vitamin C :
The biological halflife for vitamin C is fairly short, about 30 minutes in blood plasma, a fact which high dose advocates say that mainstream researchers have failed to take into account. Researchers at the National Institutes of Health decided upon the current RDA based upon tests conducted 12 hours (24 half lives) after consumption. Mainstream medicine remains skeptical of these claims.
This is a very comprehensive info sheet, which also deals with saturation levels. Linus Pauling believed in taking massive doses of Vitamin C (and took them himself). Here, they say in the light of research since Pauling they recommend less. The toxicity section refutes a research finding on vitamin C and cancer and has an explanation at Vitamin C doesn’t cause cancer!
A link from the main page titled:
recommends 400 mg/day of vitamin C taking into account saturability. But there is no mention of what you would be getting anyway from a healthy diet. Assuming at least 100 mg. per day in your food, would you want to take a further 400 mg. supplement?
Right at the end it says:
…the Linus Pauling Institute’s recommendation is strictly directed towards prevention of disease in healthy individuals, not treatment of disease. Thus, individuals suffering from certain diseases may require substantially larger amounts of vitamin C to achieve optimum body levels or derive therapeutic benefits, areas that were of great interest to Linus Pauling and need to be further explored.
This a very short one-page sheet which recommended 100 mg. a day which is just above the RDA for Vitamin C.
This fact sheet has a handy chart for food sources of vitamin C. For example, 1/2 a cup of red bell pepper provides 90 mg.
The Vitamin C Foundation (Who they? Sounds impressive… but) recommends 3000 mg. a day (3 x 100). It includes a chart covering different recommendations, starting with the U.S. RDI of 60-95 mg. An associated article, The Nature of Vitamin C, deals in detail with whether ascorbic acid is vitamin C and whether “vitamin C complex” found in food is better for you than plain old ascorbic acid or its sodium or calcium salt.
Look at a standard bottle of Vitamin C from a supermarket or pharmacy. It might say it contains Vitamin C and sodium ascorbate. I would guess most people, if they bother to look at the small print on the label, would think these were separate things. Well are they? Vitamin C page from The Linus Pauling Instititute Micronuitrient Information Center provides the answer. There is now the question of whether you might need to avoid sodium ascorbate if trying to reduce sodium intake for blood pressure. I’ll find out don’t worry! Oh, and also by the way, the main page mentions taking vitamin c for high blood pressure.
The Vitamin C Foundation page is an illustration of how difficult for the ordinary person to sort fact from fiction. There is also discussion – amongst other things – of ways in which the amount of vitamin C we need might be assessed, for example based on what other species use (though they make their own).
Most simians consume the vitamin in amounts 10 to 20 times higher than that recommended by governments for humans. This discrepancy constitutes the basis of the controversy on current recommended dietary allowances (see Vitamin C as a macronutrient – Evolutionary rationales).
An adult goat, a typical example of a vitamin C-producing animal, will manufacture more than 13,000 mg of vitamin C per day in normal health and the biosynthesis will increase “many fold under stress”.
Trauma or injury has also been demonstrated to use up large quantities of vitamin C in humans.
Mike Adams, writing in Natural News, is a believer in “natural” vitamins as opposed to synthetic ones. That aside, his February 28 2007 article
deals with the issue of absolute risk over relative risk.
He has recently, 16 April 2008, written again on the vitamin scare
If you look at his site you will discover he doesn’t believe pharmaceuticals are good at all, having claimed to have cured himself of type II diabetes through exercise and diet. I wonder if he would recommend not taking epilepsy drugs.
Debunker site. Useful for junk science debate.
Manufacture of vitamin C
Another fascinating area, which would not have popped up without this search: who manufactures vitamin C and wholesale prices.
China makes 60 per cent of the world’s vitamin C supply, with the four leading Chinese producers making 60,000 tons. About 80 per cent of this is exported to Europe.