Assessing and managing drug-nutrient interactions.

Drug-nutrient interactions can occur through many mechanisms. The amount of protein in the diet and the presence of micronutrients, such as polycyclic aromatic hydrocarbons and indoles, can affect drug metabolism. Although furanocoumarins in grapefruit juice can interact with certain oral medications, noninteracting medications generally can be substituted. Pharmacists need to provide patients with accurate information about drug-nutrient interactions and help to clarify common misconceptions about these effects.