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Does Caffeine Affect Calcium Absorption?
Slightly. Caffeine reduces calcium absorption to a small extent; low vitamin D status reduces it more.[1]
Based on NIH Office of Dietary Supplements — Calcium fact sheet · Updated October 10, 2026
Caffeine slightly reduces calcium absorption[1]
Caffeine reduces the net absorption of dietary calcium to a small extent.
The effect is small; low vitamin D status reduces calcium absorption more.
Source [1]Calcium: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. (ods.od.nih.gov)
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- Should You Take L-Theanine With Caffeine?In one trial, L-theanine with caffeine improved some attention and memory measures and alertness compared with placebo.
- Does Caffeine Cancel Out Melatonin?Evening caffeine can delay the body’s own melatonin rhythm.
- Does Salt Affect Calcium?Yes. A high sodium intake increases the calcium lost in urine, so eating less sodium means less calcium lost.
- Should You Take Vitamin D With Calcium?Vitamin D is needed to absorb calcium, and bone needs both: low calcium and/or vitamin D contributes to osteoporosis.
- Can You Take Iron and Calcium Together?Possibly. Calcium might interfere with iron absorption, so experts suggest taking calcium and iron supplements at different times of day.
Sources
- Calcium: Fact Sheet for Health Professionals. NIH Office of Dietary Supplements. ods.od.nih.gov
This page is general information from the cited sources, not medical advice. If you take prescription medication, are pregnant, or manage a health condition, check supplement changes with a pharmacist or doctor.