Health Questions and Answers

Question: What are the possible interactions between food and drugs?


Metabolic mechanisms of nutrition and drug interactions include (1) the effects of diet on drug kinetics and action and (2) the effects of drugs on nutritional processes. The type, amount, and timing of foods consumed influenced drug dissolution, absorption, distribution, metabolism, and excretion. High-fat meals enhance the absorption of griseofulvin and some other drugs. Milk and other sources of calcium inhibit absorption of tetracycline. High-fat meals increase plasma concentrations of free fatty acids and thereby displace many drugs from binding sites on plasma albumin. High-protein diets increase the activity of the mixed-function oxidase system and enhance the metabolism of numerous drugs. High electrolyte intakes increase excretion of lithium and also diminish the action of diuretics agents. Bile acid sequestrants and some laxatives decrease lipid digestion and absorption, as well as absorption of the fat-soluble vitamins. Numerous drugs, including tetracyclines and cholestyramine, bind iron and decrease its absorption. Warfarin sodium (Coumadin) inhibits the function of vitamin K and vice versa. Phenobarbital and other anticonvulsants are inducers of cytochrome P-450 and the mixed- function oxidase system. Long-term treatment with these inducers can cause excessive metabolism and deficiency of Vitamin D. Pro-oxidant drugs, such as chloroquine, drugs detoxified by conjugation with gluthathione, and alcohol, can deplete reduced gluthathione with consequent effects on amino acid transport and the oxidation-reduction status of cells.

Reference: Hathcock JN: Metabolic mechanisms of drug-nutrient interactions. Fed Proc 44:124-129, 1985

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