Iron absorption is aided by vitamin C. However, the interaction of micronutrients is not always cooperative. Vitamin C, for example, inhibits your body's capacity to absorb the vital mineral copper. Even a slight excess of the mineral manganese can exacerbate iron deficiency. The same goes for zinc: Too much of it can block iron uptake. Because of these interactions, nutritionists generally recommend that people at risk for iron deficiency avoid taking large amounts of vitamin C at once. They also advise against supplementing with both nutrients because this could cause either one to be depleted too quickly. Rather, vitamin C should be taken regularly as part of a healthy diet that includes other foods that are good sources of iron. Vitamin C helps your body use iron from food effectively. So if you're eating a balanced diet, you shouldn't need a supplement. However, if you aren't getting enough fruits and vegetables, then you might want to consider adding some supplements to meet your daily needs. Some studies suggest that vitamin C may help prevent cancer. But research shows that high doses used in some clinical trials may not be safe over time. Long-term safety data are needed before we can make any conclusions about the effects of vitamin C on health.