Caffeine, urinary calcium, calcium metabolism and bone.
Level 5 - mechanism / opinion, no new human data
Narrative review synthesizing mechanistic, animal, human, and epidemiological data
PubMed 8360789 · doi:10.1093/jn/123.9.1611
What was done
This paper reviewed mechanistic data, animal models, human metabolic studies, and epidemiological surveys examining the effects of oral caffeine intake on urinary mineral excretion, calcium absorption, calcium balance, and the risk of osteoporosis across different demographic groups.
What was found
Oral caffeine consumption increased urinary excretion of calcium, magnesium, sodium, and chloride for at least 3 hours after intake. The hypercalciuric response was proportional to dose per lean body mass, was inhibited by adenosine receptor agonists, and showed no adaptation over continuous consumption. Younger adult women consuming adequate calcium appeared to compensate for increased losses via higher intestinal calcium absorption, resulting in little or no observed deleterious effect from moderate caffeine intake. However, older women did not appear to compensate adequately to maintain calcium balance, particularly when baseline calcium intake was below recommended levels. The abstract reported no specific numerical effect sizes or quantitative ranges for caffeine dosage.
Why it matters
These findings suggest that the skeletal risks of moderate caffeine consumption are largely dependent on age and baseline calcium intake, with older individuals with inadequate calcium intake being the most vulnerable to negative calcium balance.
Limits
The abstract describes a narrative review rather than a systematic review or meta-analysis. No sample sizes, effect sizes, risk ratios, or specific numerical thresholds for caffeine dosage or calcium intake were reported.
Cited by
- context Caffeine intake inhibits the absorption of minerals, particularly magnesium.