Researchers from Creighton University in Nebraska have found that people who rely on fortified orange juice for a source of calcium, may not be getting what they expect.
When researchers compared two brands of calcium-fortified orange juice, they found that one type of calcium was actually absorbed almost 50% better. According to researchers, the quality of the fortification may affect how much can actually be absorbed, regardless of the amount of calcium added.
To investigate, researchers had 25 healthy young women drink the two test juices, on separate days, with breakfast. The researchers then took blood samples to measure how well the calcium from each juice was absorbed. Servings of each juice provided 500 milligrams of calcium -- one in the form of calcium citrate malate, the other through a combination of tricalcium phosphate and calcium lactate.
The researchers found that, on average, the women's absorption of the calcium citrate malate was 48 percent greater compared with the calcium in the other product.
While it is not clear why the calcium in different foods varies in its bioavailability or absorbability, these findings do confirm past research showing that calcium added to foods can vary widely in its absorbability.
Currently, calcium comes in about a dozen forms that can be added to foods. However, even knowing the form cannot assure consumers of the calcium's bioavailability. Calcium carbonate, for example, has been found to vary in absorbability depending on the product.
This study was partially funded by Tropicana, maker of the orange juice containing the better-absorbed calcium citrate malate.
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