Drug-Nutrient Interactions

Overview

• Drug-nutrient interactions are significant but not systematically studied.
• Interactions may affect the kinetic/dynamic parameters of drugs or nutrients by 20% to be considered clinically significant.
• Long-term drug use often required to reach clinically significant interaction levels.

Common Interactions

Alcohol

• Folate, Riboflavin, Thiamin, Vitamin A, B6
  • Chronic alcohol abuse can lead to deficiencies due to low dietary intake, decreased absorption, or increased excretion.
  • Actions: Ensure adequate intake or supplement to prevent deficiencies.

Antacids

• Folate, Fluoride, Iron, Magnesium, Manganese, Phosphate
  • Can impair absorption of nutrients due to altered gastrointestinal pH.
  • Actions: Separate intakes by a few hours to mitigate interaction.

Aspirin

• Vitamin C, Vitamin E
  • May cause increased excretion of Vitamin C and interact with Vitamin E.
  • Actions: Ensure adequate Vitamin C intake, avoid high-dose Vitamin E with aspirin.

Bisphosphonates

• Calcium, Iron, Magnesium, Zinc
  • Concomitant intake can decrease absorption due to complex formation.
  • Actions: Separate by 2 hours to ensure proper absorption.

Carbamazepine

• Biotin
  • May inhibit absorption and increase catabolism.
  • Actions: Monitor biotin status, especially with long-term use.

Cholestyramine

• Folate, Fat-soluble vitamins (A, D, E, K)
  • May bind and decrease absorption, increasing deficiency risk.
  • Actions: Supplementation and separating intake times recommended.

Metformin

• Vitamin B12
  • Interferes with absorption, possible deficiency risk.
  • Actions: Monitor B12 status.

Phenytoin

• Folate, Thiamin, Vitamin D, Vitamin K
  • Can decrease absorption or increase excretion, leading to deficiencies.
  • Actions: Supplementation may be necessary.

Warfarin

• Vitamin K, Vitamin E, Vitamin C
  • Interactions affecting coagulation.
  • Actions: Monitor intake to ensure stable INR, avoid large fluctuations.

Special Considerations

• Grapefruit: Inhibits CYP3A4, increasing drug bioavailability and risk of toxicity.
• Herbs/Supplements: Many herbs can interact with drugs like warfarin, requiring careful monitoring.

Recommendations

• Separate nutrient and drug intakes by a few hours to reduce interaction risk.
• Monitor patients' nutritional status regularly, especially during long-term drug therapy.
• Consider supplementation for at-risk nutrients when interactions are known.