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OfficeHours: Vitamins & Minerals

High-yield clinical review of vitamin/mineral deficiency, toxicity, dosing pearls, and drug–nutrient interactions.

Vitamins

Drug/Class	Nutrient Effect	Clinical Result	What to do
Metformin	↓ B12 absorption	Neuropathy/macrocytosis	Check B12 in long-term use/symptoms
PPIs/H2 blockers	↓ B12, ↓ iron absorption	Anemia risk	Reassess need; monitor
Orlistat / bile acid resins	↓ ADEK absorption	Bruising, low D	ADEK supplement; separate dosing
Loop diuretics	↑ Mg loss	Refractory hypokalemia	Replace Mg first
Thiazides	↓ urinary Ca	Hypercalcemia risk	Monitor Ca in at-risk pts

Suggested build order (highest yield first): Vitamin D → B12 → Iron → Magnesium → Folate → Thiamine → Vitamin K → Zinc/Copper