Supplement interaction
These two supplements may interact. Here's what you need to know before taking them together.
Calcium and Magnesium compete for absorption, particularly at high doses. Taking 500mg+ of calcium alongside magnesium can reduce magnesium absorption. However, at typical supplemental doses, the interaction is less severe than calcium-iron or calcium-zinc.
Take Calcium and Magnesium at different times of day. A practical split: Calcium in the morning with food, Magnesium in the evening (magnesium glycinate before bed can also support sleep quality).
Quick facts
Calcium and Magnesium share some intestinal absorption pathways, creating competition when taken together. The interaction is dose-dependent — at high calcium doses (800mg+), magnesium absorption drops more significantly.
Interestingly, both minerals need each other for proper function. Magnesium is required for calcium metabolism and helps prevent calcium from depositing in soft tissues. This is why separating them in time (not eliminating either) is the right approach.
The ideal split depends on your forms. Calcium absorbs better with food, so take it with a meal. Magnesium glycinate or threonate taken before bed can support sleep quality — making evening the natural time slot.
If you take both at the same meal, keep total doses moderate (under 400mg calcium, under 200mg magnesium). At these levels, the competition is minimal.
Can I take Calcium and Magnesium together?
You can take them at the same meal in moderate doses (under 400mg calcium). At higher doses, separate them by 2-4 hours for better absorption of both.
What happens if I take Calcium and Magnesium at the same time?
At high doses, calcium can interfere with magnesium absorption. The effect is moderate — less severe than calcium-iron — but separating them optimizes both.
How far apart should I take Calcium and Magnesium?
2-4 hours is sufficient. Morning calcium with food, evening magnesium before bed is a popular and effective approach.
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