Upset stomach. Side effects of taking calcium treatment include an upset stomach. Therefore, taking calcium acetate with food can help to neutralize this side effect. It is used in kidney disease to bind to phosphate to lower blood phosphate levels.
Better absorption. Calcium is poorly absorbed if there is no acid in the stomach. Because many people, especially those who take acid blockers, have low stomach acid, we recommend that you take calcium with food. For reasons that we do not know, calcium is well absorbed with food even if there is low stomach acid.