Nearly 1,300 people (average age 71) from five European countries initially had their bone mineral density (BMD) measured. Half were assigned a Mediterranean-style diet and given individualized dietary advice, some of the foods in the diet (such as whole-grain pasta, olive oil, and low-fat cheese), and low-dose vitamin D capsules (400 IU a day); the other half were just given leaflets about healthy eating.
After a year, repeat testing found that the diet-plus-vitamin intervention had no effect overall on BMD. However, a separate analysis of the 54 people with osteoporosis found that those on the diet-plus-vitamin group had a slight increase in BMD in the hip (femoral neck), while the control group lost more bone there.
The low-dose vitamin D supplement was given not to “optimize” vitamin D status but to minimize differences between study sites (which were throughout Europe), in which habitual diet and sunlight exposure could affect vitamin D status. “In this combined intervention design it is not possible to disentangle the relative influence of the Mediterraneandiet and/or vitamin D on femoral neck BMD in osteoporotic subjects. However, it is likely that the daily dose of vitamin D3 was too low to have a significant impact on bone loss,” the researchers noted.
Because of the relatively small number of participants with osteoporosis in the study and the limited time frame, the findings will have to be confirmed by longer, larger studies.