Calcium citrate and Iron bisglycinate: interaction, severity and spacing
Calcium citrate and Iron bisglycinate interact because 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. Take them 2 hours apart. Severe risk.
The interaction in detail
| Pair | Calcium citrate and Iron bisglycinate |
|---|---|
| Type | Nutrient interaction |
| Severity | Severe |
| Required spacing | 2 hours minimum |
| Onset | At the time of dosing |
Mechanism
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.
What to do
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.
How to fit both into one day
Calcium absorbs better with food and in doses at or below 500 mg. Take it with vitamin D3, and separate it from iron, zinc and thyroid medication.
Non-heme iron absorbs best on an empty stomach with vitamin C. Coffee, tea and calcium can halve absorption, so keep them two hours away.
Putting Calcium citrate in the midday and Iron bisglycinate in the morning satisfies the 2-hour separation without disrupting either one's absorption window.