Should calcium be taken with food?

Usually yes. Absorption of calcium supplements is greater with food, even in people with low stomach acid.^[1] Calcium carbonate in particular may be absorbed poorly without a meal in people with low stomach acid. Calcium citrate can be taken without food.^[1]

Taking the supplement with meals can also ease gas, bloating and constipation.^[1] Oxalic acid in foods such as spinach and phytic acid in other plants bind calcium, and caffeine and phosphorus lower its absorption a little.^[1]