Medications, together with environmental pollutants, food additives, pesticides, herbicides and other chemical compounds, are xenobiotics. That means that the body does not metabolize them as nutrients but rather as foreign compounds it needs to eliminate quickly.

Medications are necessary, and humans would not have been able to survive infections and other illnesses without them. A good macro- and micro-nutritional status will help the body metabolize the medication correctly.

The elderly are more likely to take multiple medications (polymedication), both prescription and over-the-counter, than younger patients. They have a greater risk of interactions between the medications themselves and foods due to age-related physical changes, such the increase in tissue and worsened functioning of the liver.