Nutrition can affect the body’s response to drugs; conversely, drugs can affect the body’s nutrition.
Some foods affect the body’s response to drugs. For example, tyramine, a component of cheese and a potent vasoconstrictor, can cause hypertensive crisis in some patients who take monoamine oxidase inhibitors and eat cheese.
Nutritional deficiencies can affect drug absorption and metabolism. Severe energy and protein deficiencies reduce tissue enzyme concentrations and may impair the response to drugs by reducing absorption or protein binding and causing liver dysfunction. Changes in the gastrointestinal tract can impair absorption and affect the response to a drug. Deficiency of calcium, magnesium, or zinc may impair drug metabolism. Vitamin C deficiency decreases activity of drug-metabolizing enzymes, especially in older people.
Many drugs affect appetite, food absorption, and tissue metabolism (see table Effects of Some Drugs
Effects of Some Drugs on Appetite, Food Absorption, and Metabolism
Drugs | Effect |
|---|---|
Increases appetite | |
Decreases appetite | |
Decreases absorption of fats | |
Increases blood glucose levels | |
Decreases blood glucose levels | |
p | Decreases blood lipid levels |
Increases blood lipid levels | |
Decreases protein metabolism |
Certain drugs affect mineral metabolism (see table Possible Effects of Drugs on Mineral Metabolism). Certain antibiotics (eg, tetracyclines) reduce iron absorption, as can certain foods (eg, vegetables, tea, bran).
Possible Effects of Drugs on Mineral Metabolism
Drugs | Effects |
|---|---|
Diuretics, especially thiazides, and corticosteroids | Can deplete body potassium* |
Laxatives if used repeatedly | May deplete potassium* |
Cortisol, desoxycorticosterone, and aldosterone† | Cause marked sodium and water retention, at least temporarily |
Impair uptake or release of iodine by the thyroid | |
Oral contraceptives | |
Certain antibiotics (eg, tetracyclines) | Reduce iron absorption |
† | |
Certain drugs affect vitamin absorption or metabolism (see table Possible Effects of Drugs on Vitamin Absorption or Metabolism).
Possible Effects of Drugs on Vitamin Absorption or Metabolism
Drugs | Effects |
|---|---|
Impairs thiamin utilization | |
Interferes with niacin | |
Inhibit folate absorption | |
Interfere with absorption of vitamin B12 | |
Oral contraceptives with a high progestin dose | |
Proton pump inhibitors | Can decrease absorption of vitamin B12, vitamin C, iron, calcium, and magnesium |
