Avmacol is an over-the counter dietary supplement containing broccoli seed and sprout extracts in tablet form. Natural plant substances within Avmacol, called phytochemicals, are hypothesized to stimulate the body's own defense mechanisms against toxic substances commonly encountered in the environment, such as air pollution and tobacco smoke. The purpose of this study is twofold: 1) to assess the protective effects of Avmacol on the mucosa (cheek cells) of healthy volunteers, and 2) to assess the collection of cheek cells by scraping, as a less invasive method of studying drug effects in the body compared to drawing blood or a tissue biopsy. Ultimately, these results will be used to design a larger study of Avmacol in patients with tobacco-related head and neck cancer. Avmacol will be studied as a way to possibly prevent a second cancer from developing in these patients.