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Multivitamin and Vitamin C can interact. Combined intake can exceed 2000mg/day UL. In iron-replete individuals, enhanced iron absorption from multivitamin iron + vitamin C may contribute to iron excess. Oxalate excretion increases, elevating kidney stone risk in susceptible individuals. Total vitamin C from all sources should remain below 2000mg/day. Space from iron-containing multivitamin if iron status is adequate. Individuals with hemochromatosis or kidney stone history should be particularly cautious.
Combined intake can exceed 2000mg/day UL. In iron-replete individuals, enhanced iron absorption from multivitamin iron + vitamin C may contribute to iron excess. Oxalate excretion increases, elevating kidney stone risk in susceptible individuals.
Multivitamins typically contain 60–500mg of ascorbic acid. Adding standalone vitamin C (often 500–2000mg) creates combined intakes near or above the 2000mg/day tolerable upper intake level. High-dose vitamin C enhances non-heme iron absorption non-selectively, potentially contributing to iron overload in susceptible individuals (hemochromatosis). Above 1000mg/day, excess is excreted as oxalate, increasing kidney stone risk in predisposed individuals.
What to do: Total vitamin C from all sources should remain below 2000mg/day. Space from iron-containing multivitamin if iron status is adequate. Individuals with hemochromatosis or kidney stone history should be particularly cautious.
This information is for educational purposes only. It is not a substitute for professional medical advice. Always consult a qualified healthcare provider before starting, stopping, or changing any supplement or medication.