NutriStack
Calcium and Magnesium Citrate, timing-sensitive.
High-dose calcium and magnesium compete for absorption when taken simultaneously.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
Same shape as the other 1,729 pairs in the public database.
From the interaction database
What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- Calcium and Magnesium Citrate
- Pair type
- Timing Sensitive, Synergy
- Evidence (highest tier)
- Strong
- Source citations
- 4 sources
- Stack Score effect
- −5 to your Stack Score (per scored timing-sensitive row).
- Scope
- Supplement × Supplement
- Last verified
- May 30, 2026
Timing Sensitive · Moderate evidence
Timing Sensitive
What is happening. High-dose calcium and magnesium compete for absorption when taken simultaneously.
Mechanism. Both minerals share intestinal absorption pathways including TRPM6/7 channels. Competition is dose-dependent and significant above 500mg combined.
Recommendation. If taking high doses (>500mg each), separate by 2+ hours. Moderate doses can be taken together.
Minimum separation. 120
Sources (3)
- Hendrix P et al. Divalent cation competition for intestinal absorption. J Nutr Biochem. 2005
- Liu C, Kuang X, Li K, Guo X, Deng Q, Li D. Effects of combined calcium and vitamin D supplementation on osteoporosis in postmenopausal women: a systematic review and meta-analysis of randomized controlled trials. Food & Function. 2020. PMID 33237064
- Yao P, Bennett D, Mafham M et al.. Vitamin D and Calcium for the Prevention of Fracture: A Systematic Review and Meta-analysis. JAMA Network Open. 2019. PMID 31860103
Synergy · Strong evidence
Synergy
What is happening. At moderate doses, magnesium and calcium work synergistically for bone health and muscle function. Calcium for contraction, magnesium for relaxation.
Mechanism. Calcium triggers muscle contraction via troponin-C binding. Magnesium promotes relaxation by competing with calcium at the NMDA receptor and supporting SERCA pump for calcium reuptake into SR.
Recommendation. Aim for 2:1 calcium-to-magnesium ratio. Both are essential for bone density and neuromuscular function.
Sources (3)
- Castiglioni S et al. Magnesium and osteoporosis: current state of knowledge. Nutrients. 2013
- Liu C, Kuang X, Li K, Guo X, Deng Q, Li D. Effects of combined calcium and vitamin D supplementation on osteoporosis in postmenopausal women: a systematic review and meta-analysis of randomized controlled trials. Food & Function. 2020. PMID 33237064
- Yao P, Bennett D, Mafham M et al.. Vitamin D and Calcium for the Prevention of Fracture: A Systematic Review and Meta-analysis. JAMA Network Open. 2019. PMID 31860103
Stack Score
How this pair moves the number.
Effect on the composite score
If both Calcium and Magnesium Citrate are in the same stack, this pair applies −5 to your Stack Score (per scored timing-sensitive row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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