Ask Vanessa: Medications and their effect on nutrition

Dear Vanessa,

My mother takes a number of prescription medications daily. She takes over-the-counter drugs occasionally. How can common medications affect a persons’ nutritional status adversely? She also loves coffee.

- Matthew

Dear Matthew,

Medications may alter food intake by either increasing or decreasing an adult’s appetite or the ability to eat. They may also affect the absorption, metabolism, and excretion of certain nutrients.

Here is a list of common medications and their possible dietary significance:

• Antacids: Reduced phosphorous, Vitamin A, and iron absorption
• Antiobiotics: Nausea, vomiting, and diarrhea, leading to reduced absorption from vomiting and increased excretion of multiple nutrients from diarrhea. Long-term therapy may decrease Vitamin K synthesis.
• Anticoagulants: Vitamin K counteracts medication. Consistent intake of Vitamin K is essential. Avoid high-dose supplements of Vitamins A and E.
• Aspirin: In long-term therapy: increased excretion of and decreased serum levels of ascorbic acid (Vitamin C); possible GI bleeding leading to loss of iron; Vitamin K depletion.
• Antihypertensives: Vitamin B6 depletion. Vitamin B6 supplementation is encouraged for those with marginal diets.
• Diuretics: Increased electrolyte excretion leading to potassium, magnesium, and calcium depletion.
• Laxatives: Decreased absorption of calcium, potassium, fat-soluble vitamins (especially Vitamin D).

Caffeine is a drug. It is a central nervous system stimulant and a diuretic. Often older people cannot tolerate caffeine as well as they could when they were younger; moderation in their caffeine intake is recommended to alleviate its negative effects and possibly avert the use of yet another drug for anxiety.

If your mother has a new medication, ask her doctor or pharmacist if the drug will interact with other medications, vitamins or supplements she’s taking, and what side effects, reactions or warning signs she should watch for.