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Increasing vitamin C intake has been studied for its impact on health. Physicians may recommend supplements as part of the established treatments for a variety of conditions, including:

• Major surgery or extensive burns. Due to its role in collagen formation, vitamin C may reduce the time required for tissues to heal.
  
  
• Iron deficiency. Increasing vitamin C intake helps some patients absorb more iron from food sources.

Other uses of vitamin C have been proposed based on its role in the immune system and as an antioxidant. Research has yielded mixed results and study continues. These topics include:

• Common cold. Multiple scientific studies have shown limited benefits for this use. Patients who take vitamin C supplements may have slightly shorter colds than those who do not. There is no apparent difference in the number or severity of colds. Recently, a review of 30 studies involving 11,000 participants over several decades found little evidence that vitamin C supplementation is effective in preventing or shortening colds. However, the review did find some evidence that people enduring high periods of physical stress (such as during marathons or sub-arctic exercises) may have a reduced risk of cold if they take vitamin C supplements.
  
  
• Cancer prevention and treatment. Consuming fruits and vegetables containing vitamin C has been related to cancer prevention, but it is unknown if this is caused by the vitamin or other factors. Pill supplements alone have not been proven to be effective and studies continue into treating the disease with intravenous (I.V.) doses of vitamin C.