Nutrition & Diet Therapy (7 th Edition) Medications, Herbal Supplements, & Diet-Drug Interactions...

Nutrition & Diet Therapy (7th Edition)

Medications, Herbal Supplements, & Diet-Drug

Interactions

Chapter 15


Medications in Disease Treatment

• Medications used to prevent & treat health problems

• Herbal supplements often used as alternative therapy

• Any ingested chemical can affect metabolism & produce adverse effects– Drug-drug interactions– Diet-drug interactions


Medications in Disease Treatment (con’t)

Prescription drugs– Use requires physician evaluation of

patient’s condition• Given to treat serious

conditions• May cause severe side effects

Over-the-counter drugs– Can be used safely & effectively

without medical supervision• Used for less serious

conditions• May cause adverse effects,

especially if used inappropriately

Generic drugs– Chemically identical & act the

same as original drug– Cost significantly less than brand-

name counterparts

• Although OTC drugs are considered safe enough for self-medication, they can cause adverse effects when used inappropriately



• Risks from medications– Any drug carries some

risk of adverse reaction– Drug considered “safe”

when benefits of use outweigh potential risks

– Risks greater when incorrectly used (prescribed &/or administered)

Potential Risks• Side effects• Drug-drug interactions• Diet-drug interactions• Medication errors-see

Table 15-1, Inappropriate Abbrev., p.440



• Elderly people using multiple meds are especially susceptible to adverse effects

• Patients at greatest risk– Pregnant & lactating

women– Children– Older adults– Individuals with medical

conditions that were not studied during drug development

• Health professionals should discuss risks & benefits of medications; alert patients to potential dangers & solutions



• Reducing risk– Patient counseling & education– Discussion of lifestyle or dietary practices as

alternatives to drug therapy– Assessment of all medications, including

prescription, OTC & dietary supplements– Monitoring side effects– Assessment of patient understanding of

medication use, interactions & drug safety


Herbal Supplements

• Widely used by consumers to improve general health & prevent or treat specific illnesses

• Do not require FDA approval before marketing

• FDA must show that herbal supplement is unsafe before it can be removed from marketplace (ex. ephedrine)

• Manufacturers & distributors are responsible for determining safety

• Not required to provide evidence

• FDA notification of illness or injury related to use of product is not required


Effectiveness & Safety• Benefits of use of herbal products is unclear• Many herbal “remedies” of dubious effectiveness• Efficacy: limited number of studies to support traditional

uses & benefits• Consistency in ingredients: variations occur in composition

of herb & in preparation; may contain harmful components• Safety issues: products often considered “natural,”

therefore safe; may have toxic effects, however—some serious, even dangerous

• Interactions: may potentiate or interfere with actions of other herbs or drugs

• Contamination: some products found to contain lead & other toxic metals; other contaminants include molds, bacteria, pesticides

• Adulteration of imported products, including addition of synthetic drugs not identified on labels


Use of Herbal Products in Illness

• Self-medication & herbal remedies may delay appropriate treatment & allow progression of illness

• Herbal products may interact with other medications—lack of research makes assessment of interactions difficult

• Herbal products are not reliable treatment for medical conditions


Diet-Drug Interactions

• Diet-drug interactions fall into the following categories:– Medications can alter food intake by suppressing

appetite or causing complications that interfere with food intake

– Medications can alter absorption, metabolism & excretion of nutrients

– Nutrients & other food components can alter absorption, metabolism & excretion of medications

– Some interactions between food components & medications can be toxic


Diet-Drug Interactions (con’t)

Drug Effects on Food Intake • Reduce food intake through…

– Nausea & vomiting– Alteration of taste sensations– Suppression of appetite– Drying mouth, inflammation or lesions in mouth or GI

tract– Side effects, including abdominal discomfort,

constipation, diarrhea– Drowsiness– Other symptoms-p. 447 Table 15-5– Ex: sedatives



Drug effects on nutrient absorption• Damage of intestinal mucosa: most widespread cause of problems

with nutrient absorption; especially antineoplastic & antiretroviral medications

• Drug-nutrient binding: binding of nutrients & drugs in GI tract, preventing absorption (ex. Ciprofloxacin)

• Altered stomach acidity: resulting in impaired absorption of vitamin B12, folate & iron (ex. Antacids)

• Direct inhibition: drugs that impede nutrient absorption by interfering with intestinal metabolism or transport

• To prevent diet-drug interactions, find out about all the drugs & supplements a patient takes



Dietary effects on drug absorption• Stomach emptying rate: taking medications on empty

stomach tends to increase absorption rate; taking medications on full stomach may delay its absorption rate (ex. Aspirin)

• Stomach acidity: absorption rates affected by acid or alkaline medium

• Interactions with food components: may bind with drugs & inhibit absorption

Drug effects on nutrient metabolism• Enhancement or inhibition of activities of enzymes needed

for nutrient metabolism (ex. Methotrexate with folate)• Alteration in absorption & metabolism



Dietary effects on drug metabolism• Alteration in activities of enzymes that metabolize

drugs– Increased blood concentration of drug (stronger

physiological effects)-ex. Grapefruit and statins– Decreased effectiveness of drug (ex. Warfarin and vitK)

• Counteraction of drug effects in other ways

Drug effects on nutrient excretion• Alteration in mineral reabsorption• Increased excretion of vitamins & minerals (ex. INH

and vit. B6)



Dietary effects on drug excretion• Alterations in excretion causing toxicity or reduced

effectiveness of the drug• Increased or decreased reabsorption (ex. Li and Na)• Alterations in drug actions

Diet-drug interactions & toxicity• Interactions can result in toxicity or exacerbate drug

side effects (ex. MAOI and tyramine)• Health professions must understand mechanism of

action of drugs & diet-drug interactions for identification &/or prevention


Nutrition in Practice—Complementary & Alternative

Therapies• Use of complementary & alternative medicine (CAM)

most prevalent among individuals with chronic, debilitating diseases

• Reasons for popularity include growing interest in “self-help” measures & non-invasive nature of the therapies

• National Center for Complementary & Alternative Medicine established in 1998– One of institutes making up the National Institutes of

Health– Mission is to investigate CAM through scientific

studies and to provide authoritative information to consumers & health care professionals

• Health professionals need to be familiar with CAM so they can communicate with patients & offer advice


Nutrition in Practice—Complementary & Alternative

Therapies• Role of health practioner

– Identify & communicate with patients who are using CAM

– Educate patients regarding hazards of postponing or discontinuing conventional therapy

– Educate patients regarding possible interactions & adverse reactions

– Identify ways to integrate CAM & conventional treatment

• Practitioner needs to regularly update knowledge of alternative therapies in order to knowledgably discuss options with patients

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