Vitamin C plays a crucial role in tissue repair and wound healing, among other functions. A serious deficiency in a developed country is quite rare and you would not likely require supplementation for this purpose. Vitamin C supplementation, sometimes in extremely large quantities, has been suggested for treating and preventing an eclectic mix of conditions ranging from weakened immunity to cancer. The University of Pittsburgh Medical Center and the University of Maryland Medical Center note studies looking at the effects of vitamin C on various conditions have found it might offer slight benefits for some conditions, but many have produced mixed results. Some dosage guidelines have been suggested for this vitamin, and using it in smaller amounts will likely pose little risk. If you plan on taking large doses, you should consult your doctor.
Suggested Dosages
The UMMC reports that many health professionals suggesting taking 250 to 500 mg twice a day to reap therapeutic benefit. The UPMC notes that some nutritional experts recommend taking up to 30 g daily -- they instruct you to take as much as you can up to this limit without experiencing side effects of cramping and diarrhea. It reports a lack of evidence that these mega-doses offer any health benefit, however.
The National Institutes of Health Office of Dietary Supplements notes a dose of 1.25 g daily doubled the blood concentration of vitamin C compared to eating about 200 to 300 mg daily of vitamin-C containing foods. It notes, however, that much higher doses do not appear to significantly raise levels beyond this. The UPMC also reports a study that illustrated a similar effect but notes that it did not measure the concentration of vitamin C in tissue, meaning that whether high doses would significantly increase tissue stores of the vitamin has not been established.
Side Effects
Because your body will flush out excess levels of the vitamin, it poses little risk of building up in your body to dangerous levels. If you take more than 2,000 mg a day, however, you could experience gas, diarrhea and general stomach upset.
Tips on Choosing a Supplement
Most vitamin C supplements come in the form of ascorbic acid, which your body uses just as well as the form that naturally occurs in foods. It has been suggested that certain types of vitamin C products such as esther-c or ascorbic acid combined with bioflavonoids help your body utilize the vitamin better. The NIH notes one study comparing ester-c with ascorbic acid that found ester-c increased the concentration of vitamin C in white blood cells only while blood levels remained the same for both. Another study found that all three forms of the supplement produced similar blood concentrations and urinary excretion rates. This research suggests that the more expensive forms of vitamin C supplements do not appear to help your body store more of the vitamin than simple ascorbic acid. If you have sensitivity to corn, read supplement labels carefully to see the source of the vitamin, as many have been made from it; look for supplements made from alternative sources such as sago palm.
Considerations for Use
Pregnant women taking more than 6 g daily could give birth to a child who suffers from rebound scurvy due to the sudden drop in vitamin C levels after birth, according to the UMMC. Taking more than 1,000 mg along with warfarin or other blood-thinning medications might increase the risk of bleeding. Vitamin C increases the amount of iron your body absorbs so you should not use supplements if you suffer from hemochromotosis, a condition where your body stores excess levels of iron. If you have any condition that affects your kidney, talk to your doctor before using vitamin C supplements. Some debate exists over the use of antioxidants such as vitamin C during chemotherapy as they might interfere with the actions of the medication. If undergoing cancer treatment, talk to your doctor before taking vitamin C supplements. You might need to specially time when you take your supplements based on your chemotherapy schedule. High doses of vitamin C interfere with the excretion of acetaminophen; if you use this common pain medication frequently, potentially toxic levels could build up. Vitamin C also increases aluminum absorption, which could prove problematic if you frequently use antacids that contain it.
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