The University of Pennsylvania’s Oncolink website had an article by Carolyn Vachan on dietary supplements, which is often a sore spot with doctors and medical researchers even as they are very popular with the general public. Supplements (vitamins, minerals, etc.) make up a $23 billion industry in the United States, and they are largely unregulated. Vachan recommends patients tell their healthcare teams about supplements they use, if only because some supplements could interfere with cancer treatment. More on nutrition for cancer patients.