Does it matter whether you get your calcium from orange juice, soy products, breakfast cereal or milk? It depends on whom you ask.
“Dairy is a reliable choice” whereas calcium-fortified foods are questionable, says Karen Rafferty, senior research dietitian with the Osteoporosis Research Center at Creighton University in Omaha, Neb.
She says there are many calcium-fortified foods and beverages, but the bone-building mineral may not be as readily absorbed and used by the body as it is from dairy products. And food manufacturers aren’t required to measure or disclose this calcium “bioavailability,” Rafferty adds.
But researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University in Boston have found that calcium is absorbed equally whether it is from milk, calcium-fortified orange juice or calcium carbonate supplements. Ligia Martini and Richard Wood measured calcium bioavailability in nine women and three men between the ages of 67 and 82 years. The participants consumed low-calcium (300 milligrams per day) and high-calcium (1,300 milligrams per day) diets for three one-week periods each.
The overall diet was the same for all six weeks, except for the addition of 1,000 milligrams of calcium from skim milk, calcium-fortified orange juice or a calcium carbonate dietary supplement during the high-calcium week. Calcium bioavailability was measured by analysing blood and urine samples.
The researchers concluded that in order to achieve optimal bone health, what matters most is reaching the daily recommended levels, rather than which calcium-rich source is chosen. However, researchers from Creighton University disputed the findings after they were published in the American Journal of Clinical Nutrition.
Osteoporosis Canada recommends 1,000 milligrams of calcium per day for people ages 19 to 50 years, and 1,500 milligrams per day for those age 50 and older. The national charity also recommends that people who don’t eat dairy products educate themselves on the calcium content of other foods, monitor their calcium intake carefully (possibly with the help of a dietitian) and consider taking a calcium supplement.