Increasing calcium intake is a public health priority in this country, but relying on soy beverages to boost daily calcium intake may not be a wise strategy, suggests a new study published in the American Journal of Clinical Nutrition.

Researchers at Creighton University in Omaha examined the calcium absorption (how the body utilizes calcium) from cow's milk and calcium-fortified soy beverages. The results showed that the calcium from cow's milk was more efficiently absorbed by the adult men in the study than the calcium from the soy beverage.

"Our findings show that calcium fortification of soy beverages usually fails to produce a calcium source comparable to cow's milk in terms of physical properties or absorbability," said co-author Robert P. Heaney, M.D., professor of medicine at Creighton University. "Even if a label indicates the two beverages have the same calcium per serving, the bioavailability, or the amount of calcium absorbed, from the soy beverage will be significantly less - typically 25 percent less absorbed compared to cow's milk."

Unlike cow's milk, soy beverages naturally contain very little calcium (about 10 mg per serving). Manufacturers often fortify these soy beverages with calcium, yet the amount is not regulated and the levels can vary greatly (80 mg to 500 mg per serving).

The researchers note that while it is possible for soy beverage manufacturers to add enough calcium to achieve a comparable absorption level as cow's milk, the reality is that not all brands do. According to this research, 60 percent more calcium is needed (500 mg per serving) in soy beverages for soy to be comparable to cow's milk.

"This research provides more evidence that calcium from cow's milk is the gold standard," said Gregory Miller, Ph.D., vice president of nutrition research of the National Dairy Council. "Milk provides not only one of the richest sources of well-absorbed calcium, but it contains eight other essential nutrients, including vitamin D that helps enhance calcium absorption."