Can antioxidants prevent cancer?

Question

Antioxidants are often touted as some kind of miracle cure for all kinds of illnesses. They are supposed to prevent damage caused by reactive oxygen species (ROS) to the cells by scavenging those ROS before they can cause any damage.

The link between antioxidants and cancer seems plausible at first glance, ROS can react with DNA and cause mutations through that mechanism. The accumulation of certain mutations can lead to the development of cancer, so the idea that preventing the damage caused by ROS to the DNA by consuming antioxidants could prevent cancer seems plausible.

Is there any hard evidence that consuming antioxidants can prevent the development of cancer?

Answer 1

No hard evidence yet.

From the National Cancer Institute:

Considerable laboratory evidence from chemical, cell culture, and animal studies indicates that antioxidants may slow or possibly prevent the development of cancer. However, information from recent clinical trials is less clear. In recent years, large-scale, randomized clinical trials reached inconsistent conclusions.

There is a 2003 article at the American Association for Cancer Research, the last part of the abstract states:

The use of antioxidants during cancer therapy is currently a topic of heated debate because of an overall lack of clear research findings. Some data suggest antioxidants can ameliorate toxic side effects of therapy without affecting treatment efficacy, whereas other data suggest antioxidants interfere with radiotherapy or chemotherapy. Overall, examination of the evidence related to potential interactions between ROS and dietary antioxidants and effects on human health indicates that consuming dietary antioxidant supplements has pros and cons for any population and raises numerous questions, issues, and challenges that make this topic a fertile field for future research. Overall, current knowledge makes it premature to generalize and make specific recommendations about antioxidant usage for those at high risk for cancer or undergoing treatment.