What is the fine-grained topic of the following text: Though indole-3-carbinol is not an essential nutrient, taking 300 to 400 mg of this supplement daily has been demonstrated to prevent breast cancer in preliminary studies; however, additional research is necessary to validate the purported anticancer properties of this supplement, the University of Michigan Health System warns. Only return the topic.
Indole-3-carbinol's potential in preventing breast cancer