Megadoses of vitamin C are regularly taken by a not negligible number of Italians, convinced that they have found the best way to prevent and fight various diseases. First of all, we point out that - compared to a daily requirement estimated by the most authoritative international agencies (including FAO) around 60-120 mg (0.06 - 0.12 g) - when we talk about megadoses, vitamin C intake levels exceed two grams / day, until reaching and exceeding ten grams.
Subjects who take megadoses of vitamin C can still suffer from problems of gastric acidity, with burning and reflux, especially when the vitamin is taken as such, that is in the form of L-ascorbic acid. Its salts, on the contrary, give less problems than heartburn, but take risks related to the additional intake of minerals. Thus, for example, sodium ascorbate may be contraindicated to those suffering from hypertension; 5 grams, in fact, bring more than half a gram of sodium, a quantity that is certainly not negligible, given that it would be a good rule - for healthy people but above all for hypertensives - not to take more than 2.5 grams / day (in reality the style modern food often determines decidedly superior contributions, independently of external sources). Five grams of potassium ascorbate, on the other hand, provide the body with almost a gram of potassium, which can create problems for individuals with kidney diseases or with potassium-sparing diuretics.
Among the side effects attributable to the megadoses of vitamin C there are further gastrointestinal problems (nausea, vomiting, diarrhea), so that very often - rather than indicating precise doses - it is preferable to recommend the personalized intake of the maximum quantity that does not cause gastrointestinal problems. These side effects, like heartburn, can be mitigated by splitting the megadose into at least three different daily assumptions, a practice that also multiplies the percentage of vitamin C absorbed in the intestine.
An excess of vitamin C in the diet seems to favor the synthesis of kidney stones due to the increased production of oxalates. For this reason, especially if you have a history of calculosis in your back, it is generally recommended to limit the overall dietary intake of vitamin C (diet plus any supplements) to no more than 1 g per day. The risk that vitamin C can metabolize in oxalates is higher in pyridoxine deficiency (vitamin B6), as can happen in case of colitis with recurrent diarrhea. Therefore, before taking supplements based on vitamin C, carriers of calcium oxalate stones should carry out further medical tests.
After this necessary introduction, the article does not intend to dwell on the preventive and curative utility of such practices. In fact, the editorial line of this site follows the positions dictated by official medicine, the same that has almost doubled the average life expectancy over the last century. Therefore, moreover, being aware that reiterating the uselessness of such practices certainly cannot move the proponents of the megadoses of vitamin C out of their positions, let us dwell on some simple considerations. Let us examine, in particular, the by now widespread conspiracy theory that would have been implemented by multinational pharmaceutical companies to obscure the healing virtues of vitamin C.
That what we live in is an imperfect world is certainly not a novelty, just as there is no doubt that pharmaceutical multinationals can exercise their power by indirectly influencing the relationship of people with health. What is inconceivable, however, is to use readers' ignorance and fears to inculcate the concept of "international conspiracy against vitamin C". If this were true, which is logically unthinkable, all researchers and universities in Italy and the world would be under the direct control of pharmaceutical companies. Now, if we think about our reality and the cultural revolution of '68 we obviously realize that there are many teachers with ideologies in complete antithesis with those of the most unbridled capitalism supported by the multinationals. All this to say that inevitably, if really the megadoses of vitamin C were able to keep the promises, all this would have clearly emerged for years even in the researches of official medicine. Instead all this has not happened and the few positive evidences - coming mostly from autonomous studies of some proponents of alternative medicine (such as the orthomolecular one) - contrast with those of uselessness emerged from many researches.
A case where it would perhaps be more rational to hope for the influence of pharmaceutical multinationals (the conditional is a must) is that of the relationship between vitamin PP (B3 or niacin) and cholesterol. At high dosages (about 150 times higher than the daily requirement), the integration of this vitamin has in fact been shown exceptionally able to lower the blood values of triglycerides and LDL cholesterol, raising at the same time the good fraction or HDL. However, due to the side effects associated with the treatment - even if apparently not so serious (in some subjects it can cause headache, skin redness, gastrointestinal problems, dizziness and liver function abnormalities) - drugs containing megadoses of vitamin PP (like the acipimox) are not yet widely used in the treatment of hypercholesterolemia.
Attention when using hydroquinone disinfectants because at high doses vitamin C counteracts the urinary disinfectant activity of Ericaceae (eg Uva Ursi and Corbezzolo).
