Bone Marrow Fat May Raise Osteoporosis Risk, Study Says

Excess fat in blood, muscle and the liver may increase the risk of osteoporosis, a new study suggests.

Researchers measured fat in more than 100 men and women, ageD 19 to 45, who were obese but otherwise healthy. Those with more liver and muscle fat had higher levels of fat in their bone marrow, the study found.

Higher levels of bone marrow fat put people at increased risk of fractures, according to the authors of the study published online July 16 in the journal Radiology.

"Bone marrow fat makes bones weak. If you have a spine that's filled with fat, it's not going to be as strong," study lead author Dr. Miriam Bredella, a radiologist at Massachusetts General Hospital and associate professor of radiology at Harvard Medical School in Boston, said in a journal news release.

She and her colleagues also found that people with elevated levels of fat in their blood had higher levels of bone marrow fat.

"Obesity was once thought to be protective against bone loss. We have found that this is not true," Bredella said.

Previous studies have looked at the relationship between fat and bone mineral density.

"In our study, we focused on bone marrow fat because that is where our stem cells can develop into osteoblasts -- the cells responsible for bone formation -- or fat cells," Bredella said. "We also wanted to look at the relationship between bone marrow fat and other fat components, such as those in the liver and muscle."

The study does not prove that excess blood and organ fat actually cause osteoporosis. More research is needed to explore the mechanisms involved in this association, Bredella said.

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