Switching to a Mediterranean diet rich with olive oil strengthens and protects aging bones, scientists claim.

A new study found that just two years of swapping less healthy fats for olive oil may preserve or even build bone in older people.

The Mediterranean diet is thought of as the classic eating habits of people from countries in southern Europe, and has been linked to a variety of health benefits like improving heart health and staving off cancer because it is high in fruit, vegetables, fish, nuts, whole grains and healthy fats like olive oil and low in red meat and dairy products.

Researchers said that the people who eat more olive oil had higher levels of the hormone osteocalcin, a marker associated with strong bones, in their blood.

Past research found that people in Mediterranean countries are less likely to develop osteoporosis compared to people in northern European nations, suggesting that the difference may be related to differences in dietary factors.

Osteoporosis, often called the "silent disease" because there are no symptoms before fracture, but once a person has broken a bone, their risk for breaking another bone increases significantly. It is the most common type of bone disease that leads to a heightened risk of bone fractures because bone mineral density is reduced and bone structure gradually deteriorates.

The National Institutes of Health estimates that about half of all women and a quarter of men over the age of 50 will have a hip, wrist or vertebra fracture due to osteoporosis, and currently about 12 million Americans older than 50 and half of all post-menopausal women are have osteoporosis.

The new study, published in the Journal of Clinical Endocrinology and Metabolism, looked at 127 Spanish men between the ages of 55 and 80 who were considered high risk heart patients and taking part in the Prevencion con Dieta Mediterranea (PREDIMED) study.

The men who took part in the study did not have heart disease, but were diagnosed with type 2 diabetes, high blood pressure or other cardiovascular risk factors.

The men were randomly assigned to three different diets: Mediterranean diet with mixed nuts, Mediterranean diet with at least 50ml of virgin olive oil a day and a low-fat diet.

Participants on the olive oil diet were told to use it for cooking and dressing salads, to eat more fruit and vegetables, eat less red meat, and to avoid butter, cream, fast food, cakes.  If participants drank alcohol, they were told to consume only moderate amounts of red wine.

After two years, the results showed that those on the Mediterranean diet with olive oil had a significant increase in concentrations of osteocalcin and other bone formation markers, while and no other diet in the study showed the same effect.

“The intake of olive oil has been related to the prevention of osteoporosis in experimental and in vitro models,” said lead author Dr. José Manuel Fernández-Real, of Hospital Dr. Josep Trueta in Girona, Spain said in a statement. “This is the first randomized study which demonstrates that olive oil preserves bone, at least as inferred by circulating bone markers, in humans.”

He noted that it was important to note that circulating osteocalcin was associated with preserved insulin secretion in subjects taking olive oil, suggesting that olive oil may also guard against diabetes.