Vitamin C supplements are often touted as a natural defense against a number of health conditions, such as the common cold. But while research shows that including enough vitamin C in your diet may protect against certain health problems, there's a lack of scientific evidence to support the use of vitamin C supplements.
Uses for Vitamin C Supplements
Found naturally in many fruits and vegetables, vitamin C is necessary for collagen formation, wound healing, and the repair and maintenance of cartilage, bones, and teeth. Vitamin C supplements offer antioxidant benefits and are purported to treat or prevent the following health conditions:
- cardiovascular disease
- high blood pressure
- Parkinson's disease
Some proponents also claim that vitamin C supplements can boost immunity, as well as aid in the prevention of cancer.
Benefits of Vitamin C Supplements
To date, studies on the health effects of vitamin C supplements have yielded mixed results. Here's a look at some key findings:
1) Vitamin C Supplements and Colds
In a 2007 review of 30 clinical trials (involving a total of 11,350 people), researchers concluded that vitamin C supplements did not help fight off colds in the normal population. However, the review's authors note that vitamin C supplements may be of some benefit to people living in extremely cold climates or to individuals exposed to brief periods of severe physical exercise (such as marathon runners).
2) Vitamin C Supplements and Heart Disease
Taking vitamin C supplements may not reduce risk of major cardiovascular events, according to a 2008 study of 14,641 male physicians (ages 50 and older at the study's start). For an average of eight years, study members took either a placebo or 500 mg of vitamin C in supplement form daily. (In addition, the supplement group took 400 IU of vitamin E every other day.) Study results showed that neither vitamin E nor the vitamin C supplements had any significant effect on major cardiovascular events, such as stroke and heart attack.
3) Vitamin C Supplements and Cancer
For a study published in 2009, 8,171 women took either a placebo or 500 mg of vitamin C in supplement form daily (as well as vitamin E and beta carotene every other day) for an average of 9.4 years. Study results showed that supplementation with vitamin C, vitamin E, or beta carotene did not help to prevent cancer.
Furthermore, a 2008 study involving 77,721 men and women (ages 50 to 76 years) found that long-term use of vitamin C supplements did not decrease risk of lung cancer. And in a 2004 review of 14 studies on antioxidant supplements and prevention of gastrointestinal cancers -- including four trials involving vitamin C supplements -- investigators found no evidence that antioxidant supplements prevented gastrointestinal cancers.
Are Vitamin C Supplements Safe?
Although vitamin C is generally considered safe, high doses may lead to a number of adverse effects, including kidney stones, severe diarrhea, and nausea. What's more, a 2008 study suggests that taking vitamin C supplements during cancer treatment may reduce the effectiveness of certain chemotherapy drugs.
Should You Take a Vitamin C Supplement?
Given the lack of scientific support for the health benefits of vitamin C supplements, it's important not to rely on vitamin C products for the treatment or prevention of any health condition. In order to get enough vitamin C each day, look first to food sources like citrus, strawberries, tomatoes, peppers, leafy greens, and cantaloupe.
If you're looking to treat or prevent a certain condition with vitamin C supplements -- or any kind of dietary supplement -- make sure to consult your physician before you start your supplement regimen.
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