Mediterranean Diet With Olive Oil Protects Bones

A diet low in meat and carbohydrates but with plenty of extra virgin olive oil appears to protect the bones of older men, according to the results of a study.

A Mediterranean diet that includes extra virgin olive oil can increase the levels of a bone formation marker in older men with cardiovascular or other conditions, according to the results of a study published online on August 1, 2012, in the Journal of Clinical Endocrinology & Metabolism. The Mediterranean diet emphasizes plant-based foods and monounsaturated fats along with reduced amounts of meat and carbohydrates. Olive oil provides the main source of fat for flavoring and preparing foods.

Noting that experimental models had found an association between osteoporosis prevention and olive oil intake, researchers from several institutes in Spain designed their study to determine whether similar correlations existed in humans. The researchers selected 127 men aged 55 to 80 years from a preexisting Spanish study of the Mediterranean diet. All subjects had at least 3 cardiovascular risk factors or type 2 diabetes, but had no history of cardiovascular disease.

Participants were assigned to groups guided by dieticians to follow 3 different diets: a Mediterranean diet supplemented with virgin olive oil, a Mediterranean diet supplemented with mixed nuts, or a low-fat diet. Those in the first group were advised to consume at least 50 milliliters of extra virgin olive oil per day and to substitute extra virgin olive oil for other oils. Those in the second group were provided a daily ration of 30 grams of walnuts, almonds, and hazelnuts. And those in the third group were advised to reduce fat intake from animal and vegetable sources.

The results showed that total osteocalcin levels increased for those in the Mediterranean diet plus olive oil group, but not for those in the Mediterranean diet plus nuts group or those in the low-fat diet group. In addition, CTX, a bone resorption marker, decreased in all groups, but the bone formation market P1NP, which indicates collagen synthesis, increased only in participants in the Mediterranean diet plus olive oil group.

Participants in the olive oil group had no significant changes in serum calcium, which decreased in the other groups. Participants in the olive oil group who were not taking statins also saw a significant increase in osteocalcin levels and increases in P1NP levels, as did those who added a statin during a follow-up. Participants in the Mediterranean diet plus nuts group who were taking or added statins did not have similar results, the study authors noted.

Increases in serum osteocalcin paralleled an increase in β-cell function, and researchers recommended further studies to determine whether the increased osteocalcin is a cause or consequence of the increased β-cell function.