The previous blog contained 2 charts outlining various food sources of calcium, with the amount of calcium per standard serving of each food source. The chart for non-dairy food sources of calcium states that bioavailability (ability to absorb and utilize in the body) may vary. One of the most significant factors that can reduce the bioavailability of calcium is the presence of iron. When both minerals are present, calcium binds to iron, creating a complex that is poorly absorbed and tends to constipate. The amounts of both iron and calcium absorbed are reduced in this situation, to the detriment of baby and mother.
Prenatal vitamin/mineral formulas that include calcium typically have 150 to 200 mg of calcium. Any more would lead to excessive size and/or multiple dosing. Since pregnant and lactating mothers need 1200 to 1500 mg of calcium per day, this only represents a small fraction of the daily needs for mothers during these times. It really makes no sense to seriously reduce the availability of iron, another key nutrient during pregnancy and lactation, when additional dietary sources of calcium will be needed anyway. As noted previously, there is scientific evidence that getting calcium from food sources is preferable to getting it from supplements. Additionally, the foods that are good sources of calcium also deliver many other very beneficial nutrients that help both mother and baby.