By DR. SWATI SHROFF, ABC News Medical Unit

Could olive oil be the new milk? A new study suggests that this might be the case - though not all health experts are convinced yet.

The study, which looked at 127 elderly Spanish men, found that those who ate a Mediterranean diet enriched with olive oil had higher levels of a protein called osteocalcin that plays a role in bone formation. The research was published in the Journal of Clinical Endocrinology and Metabolism.

This could be an important finding since osteoporosis is the most common bone disease in the United States, affecting more than 10 million people. Osteoporosis mainly affects elderly women, but men can develop the disease too. In 2005, there were an estimated 2 million osteoporosis-related fractures, 29 percent them in men.

Earlier studies have found that there are lower rates of osteoporosis in the Mediterranean basin, compared to the rest of Europe, and that may have something to do with the Mediterranean diet. This diet consists of minimally processed fruits, vegetables, breads, beans, nuts and seeds. Olive oil is supposed to be the main source of fat, and there is usually limited dairy, egg, and red meat.

Past studies have suggested that the Mediterranean diet has the potential to lower cardiovascular risk, increase weight loss, lower cancer risk, improve diabetes, and reduce pain and swollen joints in rheumatoid arthritis. What if improved bone health could be added to this growing list?

"We have more evidence that what is good for health in one way, tends to be good for health overall," says Dr. David Katz, director of Yale University Prevention Research Center. "The very same Mediterranean diet known to be good for cardiovascular health may also confer benefits on your bones."

However, Dr. Beth Kitchin, a patient educator at the University of Alabama at Birmingham Osteoporosis Clinic, cautions that osteocalcin is simply a marker of bone health - in other words, the new study doesn't actually look at whether the Mediterranean diet increased bone density or lowered fracture risk.

"This is very interesting data but much, much more work needs to be done before you can say if this has a true clinical impact on bone health," says Kitchin.

On this point, Katz agrees. "This is not a study of bone density, or clinical effects; it is a short-term study of biomarkers. Interesting, but [it is] more useful for hypothesis generation than anything else."

Nutritionists were also quick to point out that this study shouldn't undermine the importance of calcium and vitamin D in bone health.

"It doesn't replace calcium and vitamin D in the diet, however," says Keith-Thomas Ayoob, a dietician and professor at Albert Einstein College of Medicine. "But including all three, and regular exercise, are showing promise as the best way to ensure good bone health.

"I was brought up on a high-olive oil [Mediterranean] diet. It's how we ate. But not much milk or calcium-containing foods, and my elders paid a price for it."