NutriStack
Calcium and Strontium, timing-sensitive.
Strontium and calcium compete for the same intestinal absorption pathway, and calcium is preferentially absorbed, so taking them together substantially reduces strontium uptake.
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What the row says.
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At a glance
- Pair type
- Timing Sensitive
- Evidence (highest tier)
- Strong
- Source citations
- 2 sources
- Stack Score effect
- −5 to your Stack Score (per scored timing-sensitive row).
- Scope
- Supplement × Supplement
- Last verified
- May 30, 2026
Timing Sensitive · Strong evidence
Timing Sensitive
What is happening. Strontium and calcium compete for the same intestinal absorption pathway, and calcium is preferentially absorbed, so taking them together substantially reduces strontium uptake.
Mechanism. Strontium and calcium are divalent cations that share a common intestinal carrier system. When taken together, calcium outcompetes strontium for that transporter, lowering strontium absorption.
Recommendation. Separate strontium and calcium doses by at least 2 to 3 hours. Many people take strontium at bedtime and calcium with meals to avoid competition.
Minimum separation. 2 hours
Sources (2)
- Reginster JY et al., Strontium ranelate: a new paradigm in the treatment of osteoporosis, Expert Opinion on Investigational Drugs, 2003
- European Medicines Agency, Strontium ranelate (Protelos) Summary of Product Characteristics, 2014
Stack Score
How this pair moves the number.
Effect on the composite score
If both Calcium and Strontium 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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