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Vitamin C is an important nutrient that helps the body in a variety of ways. It helps synthesize collagen, assists with brain function, and serves as a powerful antioxidant which may help prevent certain cancers. Since vitamin C does have great benefits, and because humans cannot produce vitamin C themselves, they must get it from external sources like food or supplements. Vitamin C pills do, however, come with a number of potential risks including a number of gastrointestinal problems and kidney stones. Vitamin C also may reduce the levels of some essential nutrients, erode dental enamel, and cause allergic reactions. Some experts have also found evidence that vitamin C pills can have negative reactions when combined with some medications and can increase the risk of certain genetic mutations and birth defects. Likewise, some studies have shown that chemotherapy and radiation treatments may be altered by vitamin C.
The average recommended dose of vitamin C for adults is between 75 and 120 mg per day. In some instances, large doses of vitamin C well above the recommended level have been shown to cause indigestion, most notably when the pills were taken on an empty stomach. Other digestive-related side effects may include diarrhea, nausea, and vomiting. Some medical studies have also indicated headache, fatigue, and trouble sleeping as side effects associated with vitamin C supplements.
Reduced levels of other dietary requirements, such as vitamin B12 and copper, have been reported as side effects of taking vitamin C pills as well. According to some research, individuals taking vitamin C pills may also run the risk of improper iron absorption. Too much vitamin C can cause an excess excretion of the vitamin and its acid, which may result in the erosion of dental enamel and exacerbated allergic reactions.
Some smaller studies have also indicated that excess vitamin C intake can increase the risk of developing genetic mutations and birth defects. Some researchers have argued that not enough research has been done to concretely prove this, however. Similarly, case studies have shown the development of kidney stones that some researchers argue was connected with high vitamin C intake, but most scientists agree that further testing is required. Further testing also is being done to study whether vitamin C may interfere with the effectiveness of some medications, such as chemotherapy drugs; testing thus far has been inconclusive.
Before taking any dietary supplements, a consult with a family physician is recommended. Doctors can discuss risks and side effects and make recommendations for safe dosage levels.
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