NutriStack
Magnesium Citrate and Strontium, timing-sensitive.
Strontium and magnesium taken in the same dose can compete for absorption because both move across the gut as divalent cations using overlapping pathways. Strontium uptake is already sensitive to other minerals in the gut (this is why strontium must be separated from calcium), and magnesium falls into the same competitive category. The practical consequence is reduced strontium bioavailability when a meaningful magnesium dose is co-ingested. This is a timing issue, not a safety hazard.
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
- Magnesium Citrate and Strontium
- Pair type
- Timing Sensitive
- Evidence (highest tier)
- Emerging
- Source citations
- 3 sources
- Stack Score effect
- −5 to your Stack Score (per scored timing-sensitive row).
- Scope
- Supplement × Supplement
- Last verified
- May 30, 2026
Timing Sensitive · Emerging evidence
Timing Sensitive
What is happening. Strontium and magnesium taken in the same dose can compete for absorption because both move across the gut as divalent cations using overlapping pathways. Strontium uptake is already sensitive to other minerals in the gut (this is why strontium must be separated from calcium), and magnesium falls into the same competitive category. The practical consequence is reduced strontium bioavailability when a meaningful magnesium dose is co-ingested. This is a timing issue, not a safety hazard.
Mechanism. Strontium, calcium and magnesium are divalent cations that share common intestinal absorption pathways. Classic isolated-rat-intestine work showed mutual competition among these cations, with strontium and magnesium each capable of reducing the active uptake of the other in the small intestine, and overlapping handling at calcium-sensing receptor and TRP-family transport routes. When a sizeable magnesium dose and a strontium dose are taken together, they compete for the same finite transport and paracellular capacity, lowering the fraction of strontium absorbed (and modestly affecting magnesium uptake in return).
Recommendation. Separate strontium and magnesium by at least 2 hours. A clean stack: magnesium with dinner or earlier in the evening, then strontium at bedtime at least 2 hours later on an empty stomach. Avoid putting both in the same nighttime pill pile. Lower magnesium doses (under about 100 mg elemental) are less likely to matter, but spacing is the safe default.
Minimum separation. 2 hours
Sources (3)
- Competition Between Calcium, Strontium, and Magnesium for Absorption in the Isolated Rat Intestine, documenting mutual divalent-cation uptake competition.
- European Medicines Agency, Protelos (strontium ranelate) Summary of Product Characteristics, establishing that co-ingested cations and food reduce strontium bioavailability.
- Reviews of intestinal divalent-cation transport (calcium-sensing receptor and TRP-family transporters) describing shared handling of calcium, strontium and magnesium.
Stack Score
How this pair moves the number.
Effect on the composite score
If both Magnesium Citrate 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.
Check your full routine
One pair was the worked example. NutriStack runs every pair in your stack at once.
Drop in your supplements and prescriptions and the public database surfaces every interaction, synergy, timing rule, and contraindication, every one linked to its primary source.