CAFFEINE, URINARY CALCIUM, CALCIUM-METABOLISM AND BONE

Oral doses of caffeine increase the urinary excretion of calcium, magn esium, sodium and chloride for at least 3 h after consumption. The hyp ercalciuric effect can be blocked by adenosine receptor agonists. The effect is proportional to dose per lean body mass and no adaptation to the urinary losses occurs with continuing consumption of caffeine. Un compensated losses of calcium would be a risk factor for development o f osteoporosis. Risks of osteoporosis due to caffeine consumption are reviewed. Comparison of data from epidemiological surveys and animal a nd human studies suggests that for younger adult women consuming adequ ate calcium, moderate caffeine intakes may have little or no deleterio us effects. Increased urinary and intestinal losses may be compensated for by increased intestinal calcium absorption. However older women d o not seem to compensate adequately to maintain their former calcium b alance, especially when calcium intakes are below recommendations.