Drug-nutrient interactions in the elderly

Dietary supplement use has steadily increased among the elderly to improve or maintain overall health and for specific reasons, such as to promote bone or heart health. The use of medicinal products is also high among the elderly, thus increasing the risk for drug–nutrient interactions (DNI). Although, DNI are well recognized, their importance is slowly getting recognition as a potential factor that may affect outcomes in the elderly with multiple comorbidities requiring multiple medications, in the background of declining functional reserves, altered nutritional status, and aging-associated physiological changes that alter the disposition (absorption, distribution, metabolism, or elimination) of the drug or nutrient and its effect on the body. Nearly half of patients using dietary supplements with prescription drugs are at risk of some interaction, with a third considered clinically significant, particularly with drugs with a narrow therapeutic index. These interactions may go undetected as the majority of patients do not disclose their supplement use to healthcare professionals. Increasing recognition of such interaction may help reduce these adverse effects. In this chapter, we will summarize different types of DNI, highlight aging-associated alterations in pharmacokinetics and pharmacodynamics that increase predisposition to DNI, and discuss issues in regulating dietary supplements that can potentially improve their safety