Some absorbed calcium is eliminated from the body in urine, feces, and sweat. This amount is affected by such factors as the following:
-Sodium and protein intakes: high sodium intake increases urinary calcium excretion [13,14]. High protein intake also increases calcium excretion and was therefore thought to negatively affect calcium status [13,14]. However, more recent research suggests that high protein intake also increases intestinal calcium absorption, effectively offsetting its effect on calcium excretion, so whole body calcium retention remains unchanged .
-Caffeine intake: this stimulant in coffee and tea can modestly increase calcium excretion and reduce absorption . One cup of regular brewed coffee, for example, causes a loss of only 2–3 mg of calcium . Moderate caffeine consumption (1 cup of coffee or 2 cups of tea per day) in young women has no negative effects on bone .
-Alcohol intake: alcohol intake can affect calcium status by reducing its absorption  and by inhibiting enzymes in the liver that help convert vitamin D to its active form . However, the amount of alcohol required to affect calcium status and whether moderate alcohol consumption is helpful or harmful to bone is unknown.
-Phosphorus intake: the effect of this mineral on calcium excretion is minimal. Several observational studies suggest that consumption of carbonated soft drinks with high levels of phosphate is associated with reduced bone mass and increased fracture risk. However, the effect is probably due to replacing milk with soda rather than the phosphorus itself [20,21].
-Fruit and vegetable intakes: metabolic acids produced by diets high in protein and cereal grains increase calcium excretion . Fruits and vegetables, when metabolized, shift the acid/base balance of the body towards the alkaline by producing bicarbonate, which reduces calcium excretion. However, it is unclear if consuming more fruits and vegetables affects bone mineral density. These foods, in addition to reducing calcium excretion, could possibly reduce calcium absorption from the gut and therefore have no net effect on calcium balance.