“In our research on green tea and a nutrient in broccoli, we’ve discovered that both appear to have some beneficial effects on certain tissues, and that they are safe. But we’re still studying whether either or both actually prevent cancer,” says Dr. Howard Bailey, professor of medicine at the UW School of Medicine and Public Health. Bailey, also a practicing oncologist, is one of the main investigators for a multi-center National Cancer Institute study of soy products, green tea, vitamin D and a compound associated with certain fruits and vegetables.
Very few nutrients have been proven to have cancer-prevention characteristics, but a handful of drugs have shown promising results in clinical trials or have been proven to prevent certain cancers. Tamoxifen, originally developed to treat breast cancer, and raloxifene, first used to prevent osteoporosis, can reduce the risk of breast cancer for high-risk women. Another FDA-approved cancer-prevention drug is the HPV vaccine for cervical cancer.
While research on drugs for chemoprevention has made progress, Bailey says the study of nutrients lags behind. He says there are several theories about why there’s so much to learn about potential disease-prevention characteristics of nutrients.
“Because we’ve been exposed to nutrients and vitamins for ages, any potential health advantage to consuming them is likely to be modest. Early on, we thought we could increase the effect by increasing the dose or amount of nutrient or vitamin taken. However, the old adage about ‘too much of a good thing‘ may apply.”
Bailey says he and other researchers will try to determine the level of nutrients or vitamins needed to be effective in prevention of specific cancers. He is currently researching the effective dosage of nutrients and vitamins like green tea and vitamin D for specific diseases, including bladder and prostate cancers. He also plans to explore the idea that a one-time, large dose of vitamin D is safe and has prostate cancer-prevention properties.
For more information on clinical trials at the UWCCC, go to www.uwhealth.org/cancertrials.