Mithrandir wrote:I remember reading somewhere that the diuretic effects of caffiene were not common - or exaggerated.
So far, the vibe I'm getting is you're fine if you consume enough calcium on a regular basis, moderate your caffeine intake (defined as one cup a day) and are not over a certain older age range .
#1) Heaney RP. "Effects of caffeine on bone and the calcium economy." 2002. Food Chem Toxicol. 2002 Sep]
Caffeine-containing beverage consumption has been reported to be associated with reduced bone mass and increased fracture risk in some, but not most, observational studies. Human physiological studies and controlled balance studies show a clear but only a very small depressant effect of caffeine itself on intestinal calcium absorption, and no effect on total 24-h urinary calcium excretion. The epidemiologic studies showing a negative effect may be explained in part by an inverse relationship between consumption of milk and caffeine-containing beverages. Low calcium intake is clearly linked to skeletal fragility, and it is likely that a high caffeine intake is often a marker for a low calcium intake. The negative effect of caffeine on calcium absorption is small enough to be fully offset by as little as 1-2 tablespoons of milk. All of the observations implicating caffeine-containing beverages as a risk factor for osteoporosis have been made in populations consuming substantially less than optimal calcium intakes. There is no evidence that caffeine has any harmful effect on bone status or on the calcium economy in individuals who ingest the currently recommended daily allowances of calcium.
[B]
#2) Packard, PT., Recker, RR. "Caffeine does not affect the rate of gain in spine bone in young women." 1995. Osteoporosis International. Vol 6 (2). 149 - 152. Osteoporosis Research Center, Creighton University, 601 North 30th Street, Suite 5766, 68131 Omaha, NE, USA.
The effect of nutrition and dietary caffeine consumption and physical activity on bone gain in women during the third decade of life was determined in a longitudinal, descriptive study of 145 healthy college-aged women. Estimates of caffeine and other dietary intakes were determined by repeated 7-day diet diaries. Measurements of bone mineral in the spine and total body mineral content were determined by dual-photon absorptiometry. Measures of physical activity were ascertained by physical activity monitor. The mean estimated caffeine, calcium and protein intakes for the young women students were 103±106 mg/day (mean /+- SEM), 831±334 mg/day (mean ± SEM) and 66±16 g/day (mean ± SEM) respectively. The median rates of bone gain were 5.9% for spine bone mineral content, 6.8% for spine bone mineral density and 12.5% for total body bone mineral. In a multiple regression analysis the significant predictors (+ or –) of the rate of gain were age (–), activity (+), calcium intake (+) and protein intake (–).
Caffeine consumption was not associated with significant reduction in rates of bone gain. While calcium and protein nutrition affect bone gain in the third decade of life in women, moderate caffeine intake (one cup of coffee per day, or 103 mg) appears to be safe with respect to bone health in this age group.
#3) Massey LK, Whiting SJ."Caffeine, urinary calcium, calcium metabolism and bone." 1993. J Nutr. Sep;123(9):1611-4.
Oral doses of caffeine increase the urinary excretion of calcium, magnesium, sodium and chloride for at least 3 h after consumption. The hypercalciuric 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. Uncompensated losses of calcium would be a risk factor for development of osteoporosis. Risks of osteoporosis due to caffeine consumption are reviewed.
Comparison of data from epidemiological surveys and animal and human studies suggests that for younger adult women consuming adequate calcium, moderate caffeine intakes may have little or no deleterious effects. Increased urinary and intestinal losses may be compensated for by increased intestinal calcium absorption. However older women do not seem to compensate adequately to maintain their former calcium balance, especially when calcium intakes are below recommendations.