Supplements and Morning Coffee: Timing Iron, Zinc, Calcium, B Vitamins, and Vitamin D: Nutritionist Leyla Muedin explains that coffee (and tea) can interfere with nutrient absorption and digestion, so certain supplements shouldn’t be taken with morning coffee. Coffee’s tannins and polyphenols can significantly reduce non-heme iron absorption (decaf doesn’t prevent this), and similar binding issues may affect zinc; she recommends taking iron with water at least 1–2 hours away from coffee and pairing it with vitamin C. Because caffeine may increase urination, B vitamins (especially thiamine) may be lost more readily, so she suggests taking them with food but not with coffee. Vitamin D is best taken with a fat-containing meal (not washed down with coffee), and calcium supplements should be separated from coffee since caffeine can slightly increase calcium loss. She also notes interactions such as green tea reducing folate absorption, spinach oxalates limiting mineral absorption, phytates in bran/legumes reducing iron and zinc absorption, and calcium (milk or supplements) cutting iron absorption, emphasizing timing rather than eliminating these foods.
