Previous research has established that calcium supports bone formation and repair, while vitamin D helps the body absorb calcium.  Many experts have suggested the combination of vitamin D and calcium supplementation to reduce the risk of bone fracture among older people, particularly those at risk of or suffering from osteoporosis. M. Karkkainen, from the University of Kuopio (Finland), and colleagues analyzed data collected from participants in the Osteoporosis Risk Factor and Prevention-Fracture Prevention Study (OSTPRE-FPS), involving 3,432 women, ages 66 to 71 years.  A subset of 593 women were randomly selected for bone mineral density (BMD) measurements, with half of the women receiving the daily vitamin D plus calcium supplements, while the other group received nothing.  After three years of study, the researchers report that the total body BMD increased by 0.84% in the intervention group, compared with 0.19% increase in the control group.  Further, the team found that those women who complied the best with the supplementation protocol, taking at least 80% of the supplements, experienced the greatest benefits in BMD measurements.  The researchers conclude that: “Daily vitamin D and calcium supplementation have a positive effect on the skeleton in ambulatory postmenopausal women with adequate nutritional calcium intake. “