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Supplement interaction checker

Calcium and iron interact because they compete for the same intestinal transporter, so take them at least two hours apart. StackingRight checks every pair in your stack for that kind of conflict — across 91 sourced rules covering nutrients, medications and foods — and shows the severity, the mechanism, the spacing required and the citation for each one.

Severe
Severe
Vitamin K with warfarin, potassium with ACE inhibitors, St. John’s Wort with SSRIs
Moderate
Moderate
Calcium with iron, zinc with copper, coffee with iron
Mild
Mild
Magnesium with calcium at high doses, vitamin E with CoQ10
Synergy
Synergy
Vitamin D3 with K2, vitamin C with iron, selenium with vitamin E

Your stack

2 items selected

  • Iron bisglycinate
  • Calcium citrate

Medications and foods are included — they matter as much as supplements.

Quick start

RDA reference

Sets the daily recommended intake used to judge your totals. Upper intake levels are the same for both sexes.

75Stack Score
Stack Score

Solid

Mostly clean. A few timing or overlap issues to tidy up.

  • Critical conflicts-25.0

Interaction map

Hover a node to isolate its relationships.

Severe1Moderate0Synergy0
Iron bisglycinateCalcium citrate
ConflictSynergyWatch spacing

Flagged interactions

  • Iron bisglycinateCalcium citrate

    Nutrient interaction

    Severe

    Calcium and non-heme iron compete for the same divalent metal transporter (DMT1) in the small intestine. Calcium also inhibits iron absorption directly, and the effect is proportional to dose.

    Separate calcium and iron by at least 2 hours. Take iron on an empty stomach with vitamin C, and calcium with a meal later in the day.

    Separate by 2hSource

Nutrient totals

Everything these products supply, against your daily targets.

  • Iron25 mg / 18 mg RDA
    139% of RDABelow UL 45 mg
  • Calcium500 mg / 1k mg RDA
    50% of RDABelow UL 2.5k mg

Suggested schedule

Each item placed in the window its absorption requires.

2 items ready to place across 2 windows.

Save this stack and log it daily

An account keeps your stack, tracks what you actually took, and recomputes your score as your labs and medications change. The scan itself stays free.

Avoid the combination or separate by the full interval. Worth a prescriber conversation.

How to read a result

Severity, mechanism, spacing, action.

Every flagged pair gives you four things: how serious it is, why it happens physiologically, how many hours apart they need to be, and what to actually do. No black boxes.