Vitamin C: Have risks or side effects?

Ascorbic acid (vitamin C) is one of the vitamins which recommended intake level is still discussed. The current RDA in the United States is 60 mg. Recent evidence suggests that a more reasonable estimate of needs for health maintenance is the order of 100 mg daily. Among other countries, Canada, France and New Zealand have increased their maximum daily dose recommended for certain risk groups such as smokers and elderly people.

Why use a high dose of vitamin C?
Vitamin C is a vitamin that is being consistently delivered in high doses for long periods of time. Quantities greater than 1 g are being taken by many as prophylaxis against the common cold, in different types of cancer, drug detoxification, in cases of schizophrenia, for wound healing and the prevention of nitrosamine formation in the stomach .

Critical to the administration of high doses of vitamin C
Some critics of the administration of high doses of vitamin C have argued that the drug causes kidney stones, by increasing the excretion of oxalates, which causes interference with the metabolism of vitamin B12, which is relapse of scurvy due to the abrupt withdrawal of therapy, which causes excessive absorption of iron and has a mutagenic effect.

A deep and thorough analysis of the data, performed in recent years has dismissed all these arguments seriously about it. Some patients, particularly during the early days of the administration of high doses, if they experience a laxative effect. But even this side effect is mild and harmless, is not consistently found.

Vitamin C and oxalate kidney
The oxalates are the main metabolites of ascorbic acid. Therefore it is postulated that could lead to the formation of oxalate stones in the kidney. Recent studies have shown that the conversion of ascorbic acid in oxalate is limited, and that does not reach critical levels, even after doses of ascorbic acid as high as 10 g daily. In another recent study (Chalmers, AM, et al.: A possible etiological role for ascorbate in calculi formation. Clin. Chem 32:333-336, 1986.), The rates that came to form calculations showed excretion rates exaltaos oxalate higher than normal after an intake of 2 g of ascorbic acid. There are potential dangers for patients with kidney failure who should restrict their intake from all sources of oxalate, as well as dialysis, and therefore must be cautious with the daily intake of vitamin C.

Vitamin C and its relationship with vitamin B12
It has been shown that the alleged reduction of vitamin B12 in vitro by ascorbic acid was due to an inadequate procedure for extraction of vitamin B12. Recent studies using more reliable methods, have not shown any effect, like other extensive studies in humans have not yielded any evidence of deficiencies in vitamin B12, even after long periods of high doses of ascorbic acid.

Vitamin C, scurvy and iron absorption
Some anecdotal reports have circulated and lack of control over recurrence of scurvy before the abrupt withdrawal of high doses of vitamin C. Studies carried out on guinea pigs and humans have failed to find confirmation of these observations. Although ascorbic acid increases iron absorption, there are no reports of excessive iron absorption attributable to high intakes of ascorbic acid in normal people. In rare cases of excessive gastrointestinal absorption of iron, the use of high doses of vitamin C is contraindicated.

Does vitamin C mutagenic?
The claim that vitamin C is mutagenic is very serious, and is based on the damage found in the genetic material in microbial and mammalian cells in test tubes. However, it was seen that ascorbic acid or vitamin C which was producing this effect, but the hydrogen peroxide formed by the destruction of vitamin C for pure oxygen ions or copper used in the system verification. A recent in vitro study confirmed that vitamin C is not mutagenic to mammalian cells under physiological conditions (Amacher, DE et al.: Ascorbate is not detectable mutagenic in the L5178Y TK. + / - Cell mutation assay. Cancer. Lett . 14:151-158, 1981.Norkus, EP, et al.: Studies on the mutagenic activity of ascorbic acid in vitro and in vivo. Mutation Res 117:183-191, 1983).

Vitamin C and other studies
Other minor side effects that have not been substantiated in recent studies refer to the alteration of electrolyte balance, increased lysis of red blood cells and reduction of immunological tolerance. It is important to understand that ascorbic acid is itself a reactive substance of oxidation-reduction system, and therefore can give rise to false reactions, particularly in certain analytical tests used in the colored indicators. This phenomenon has been reported in analysis of glucose, uric acid, creatinine and occult blood. However with a selection of specific enzymatic reactions, using current analytical methods, remove the difficulties presented nonspecific reactions.

Overall, according to a recent comprehensive review of scientific data concluded that vitamin C is a safe substance, even in daily intakes about 100 times the RDA.

Values of the RDA for men 23 to 50 years of age and their relationship "High Security" / RDA

RDA                                Vitamin                            Security Level
1.4 mg                         Thiamin (B1)                          over 100          
1.6 mg                         Riboflavin (B2)                       over 100
18 mg                          Niacin (B3)                         NE about 100
4-7 mg                  Pantoténico1 acid (B5)                over 100
2.2 mg                       Pyridoxine (B6)                            100
400 ug                       Folic acid (B9)                           over 50
3 ug                             Vitamin B12                             over 100
60 mg                           Vitamin C                            about 100
100-200 ug                  Biotin (B7)                              over 100
5 ug (200 IU)                Vitamin D                                about 10
10 mg-TE (15 IU)         Vitamin E                                over 100
70-140 ug                    Vitamin K                                 over 50
1000 ug RE2                Vitamin A                               around 10 *

about 3 **

NE = Niacin equivalent in

RE = Retinol Equivalence in

TE = Tocopherol

1 = estimate of a safe and adequate level instead of RDA, due to limited available evidence.

2 = is the equivalent of 3333 IU of retinol or 5000 IU vitamin A diet.

* = Relationship between the levels are still considered safe in the vast majority of adults and RDS Standard.

** = Women of childbearing age.

Source: Lamberts medicines.

Related topic:
Vitamin C: General
What is orthomolecular nutrition

*Automatic Translation