Drug Nutrient Interactions

FDA definition of dietary supplements

dietary substance for use to supplement the diet by increasing the total dietary intake; can be vitamins or minerals, amino acids, herbs, etc

Dietary Supplement Health and Education Act

categorizes dietary supplements as a type of food, not as a drug

the FDA can remove a product from the market if it is proven to be unsafe

products must be clearly labeled as a dietary supplement that is intended for ingestion

Food, Drug, and Cosmetics Act

began government regulation of drugs in the US

Type 1: ex-vivo bio inactivation

drugs and nutrients react outside of the body and inactivate each other

Situation: drugs and nutrients administered intravenously or via a feeding tube

Guide: separate food and drug administration

Type 2: absorption phase

modification of bioavailability and absorption and modification to enzymes and transport proteins

Situation: limited to oral or enteral administration

Guide separate/ increase time between drug and nutrient

Type 3: Physiologic Action

post-absorption: involves the distribution, metabolism, transport, or penetration to a specific organ or tissue

may involve changing the function of cofactors

guide: Separation does not help. Dose adjustment or limiting intake of certain foods is necessary

Type 4: elimination

elimination or clearance of the drug or nutrient is impacted

situation: renal or liver metabolism or excretion

guide: Separation does not help. Does adjustment or limiting intake of certain foods is necessary

Give an example of a medication that can decrease food intake

several cancer medications and treatments can cause nausea, vomiting, sore or dry mouths, resulting in poor food intake

Give an example of a medication that can decrease nutrient absorption

laxatives can decrease the absorption of many vitamins and minerals as well as other drugs,

Give an example of a food that decreases the absorption of a drug

dietary calcium can bind to the antibiotic tetracycline, resulting in decreased tetracycline absorption

Supplements that can interact with oral contraceptives

St. John’s wort, kava

Supplements that can interact with chemotherapy

St. John’s wort, ginseng, kava, cranberry

Supplements that can interact with hypoglycemic agents

garlic, cranberry, ginko, ginseng