Can vitamin C be harmful?
Vitamin C is widely “recommended” to help prevent colds and flu, but can it also harm us?
Although this subject is not much debated because it is thought that vitamins in general are that type of product that “if it doesn't do any good, it doesn't do any harm either”, some warnings have been made regarding the consumption of vitamin C. Daily doses more than 1000 mg can cause diarrhea, kidney stones in more susceptible people and changes in the menstrual cycle. Sudden interruption of these high doses can also cause scurvy due to the “ricochet” effect.
But in addition to the above, the impact that the daily consumption of 1 gram of vitamin C has on the bioavailability of some medicines has been studied.
The isoenzymes of the CYP 3A4 family were the target of studies that revealed the potential that vitamin C has to induce them. In practice, consuming this vitamin in doses equal to or greater than 1 gram can reduce the permanence of certain medications in our body, which can compromise the effectiveness of the treatment.
Some of the medications that may be affected are used in the treatment of Cancer (Paclitaxel, Tamoxifen, Vinblastine, Vincristine, Irinotecan, Vinorelbine, among others), AIDS (Atazanavir, Indinavir, Ritonavir, Saquinavir, among others), Depression (Amitriptyline, Citalopram, Fluoxetine, Mirtazapine, Sertraline, Trazodone, Venlafaxine, among others), Hypercholesterolemia (Atorvastatin, Lovastatin, Simvastatin) and many other diseases.
Although the extent of this inductive effect may vary depending on gender, and more studies are still needed to better understand these differences, the results of this interaction may be clinically relevant, especially in medicines with narrow therapeutic windows.
Bibliography:
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Taylor, E. N.; M. J. Stampfer, et al. Dietary factors and the risk of incident kidney stones in men: new insights after 14 years of follow-up. Journal of the American Society of Nephrology 2004; 15(12): 3225-3232.
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Slain, D.; J. R. Amsden, et al. Effect of High?Dose Vitamin C on the Steady?State Pharmacokinetics of the Protease Inhibitor Indinavir in Healthy Volunteers. Pharmacotherapy: The Journal of Human Pharmacology and Drug Therapy 2005; 25(2): 165-170.
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Heeswijk, R. P. G.; C. L. Cooper, et al. Effect of High?Dose Vitamin C on Hepatic Cytochrome P450 3A4 Activity. Pharmacotherapy: The Journal of Human Pharmacology and Drug Therapy 2005; 25(12): 1725-1728.