NutriStack
Calcium and Manganese, timing-sensitive.
High-dose calcium can reduce manganese absorption when taken together, lowering the amount of manganese the body takes up from a given dose.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
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What the row says.
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At a glance
- Pair type
- Timing Sensitive
- Evidence (highest tier)
- Emerging
- 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 · Emerging evidence
Timing Sensitive
What is happening. High-dose calcium can reduce manganese absorption when taken together, lowering the amount of manganese the body takes up from a given dose.
Mechanism. Calcium can interfere with intestinal absorption of manganese through competition and binding effects in the gut, decreasing manganese bioavailability when the two are consumed at the same time.
Recommendation. Separate calcium and manganese by at least 2 hours to avoid reduced manganese absorption, particularly if using high-dose calcium supplements.
Minimum separation. 2 hours
Sources (2)
- Davidsson L et al. Manganese absorption in humans: the effect of phytic acid and ascorbic acid in soy formula. Am J Clin Nutr. 1995. PMID 7572746
- Lonnerdal B. Dietary factors influencing manganese absorption in humans. Nutrition Reviews, 1997.
Stack Score
How this pair moves the number.
Effect on the composite score
If both Calcium and Manganese 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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