When it comes to bone growth and strength, there's nothing better than milk and dairy. It even beats out synthetic calcium carbonate to ensure bone health.
In the study, researcher Connie Weaver found that the bones of rats fed non-fat dry milk were longer, wider, more dense and stronger than those of rats fed a diet with calcium carbonate.
Weaver said the study is the first direct comparison of bone properties between calcium from supplements and milk.
"A lot of companies say, 'If you don't drink milk, then take our calcium pills or calcium-fortified food'. There's been no study designed properly to compare bone growth from supplements and milk or dairy to see if it has the same effect," Weaver said.
The study involved 300 rats that were divided into two groups. For 10 weeks, the rats were given all the nutrients they require, but one group was given dairy and the other was given calcium carbonate as the source of calcium.
After 10 weeks, the bones of 50 rats from each group were measured for strength, density, length and weight.
"We found those measurements were up to 8 percent higher for those who had milk over calcium carbonate," Weaver said.
The study also found a strong effect of having dairy as a calcium source followed by periods of inadequate calcium.
Over a second 10-week period, the remaining rats were fed as adults. Half of those were given adequate calcium as carbonate or milk. The other half were switched to half as much calcium as recommended, but were given calcium carbonate.
"This is comparable to humans who, during their early growth, drink a lot of milk to the age of 9 to 11, or maybe even adolescence, but then get only half as much milk calcium as they need after that," Weaver said. "Some take calcium supplements, but few adults get adequate calcium."
The study showed the rats raised on dairy still had advantages over those who were given calcium carbonate even later when they were given half enough calcium as dairy or calcium carbonate.
"We found it was an advantage having milk or dairy while bones were growing over calcium carbonate, and it protects you later in life," Weaver said.
The study will be published in the August print issue of the Journal of Bone and Mineral Research.