"There are few studies examining the effectiveness of supplementing the diet with calcium and vitamin D for preventing or maintaining bone health in men," explained lead author Robin Daly from Deakin University.
Much focus has been on the vitamin D and calcium combination for bone health in women since elderly females are four times as likely to develop osteoporosis than their male counterparts. The new study, published on-line in the journal Bone (doi: 10.1016/j.bone.2006.04.003), reports that elderly men, particularly those over 62, benefited from daily supplements of fortified milk.
Osteoporosis is estimated to affect about 75m people in Europe, the USA and Japan. According to the International Osteoporosis Foundation, the total direct cost of osteoporotic fractures is €31.7bn in Europe, and 17.5bn in the US (2002 figure).
Recent studies, including the high profile WHI study, have shown that vitamin D/ calcium supplementation could reduce the incidence of hip fracture in post-menopausal women by about 20 per cent. The overall study however was blighted with poor compliance with taking the supplements.
Daly and his colleagues, Shona Bass and Caryl Nowson, randomly assigned 61 male volunteers over the age of 50 to receive daily supplements of a fortified milk containing 500 milligrams of calcium (milk calcium salt NatraCal) and 400 International Units (IU) of vitamin D3 (DSM Nutritional Products), and was formulated by Murray Goulburn Co-operative in Brinswick, Australia. A further 50 volunteers (control group) received no supplement and continued to eat their normal diet.
Bone mineral density (BMD) and bone geometry were measured using a Siemens Emotion duo scanner to determine the quantitative computed topography (QCT).
After two years no significant difference between the groups was observed for total bone area. However, significant and beneficial changes were observed in the mid-femur bone material and geometric properties, particularly for men over 62.
"This finding supports current recommendations that older adults have increased dietary requirements for calcium and vitamin D," wrote Daly.
The mid-femur medullary area (bone marrow) increased less in the milk-supplemented group than the control group, which helped to preserve the cortex (outer layers) of the bone. Thinning of the bone cortex is one of the signs of increased fracture risk.
The loss of mid-femur cortex density was 2.3 per cent in the supplemented group than in the control group, showing that the bones were benefiting from the milk supplementation.
Due to the complicated nutritional mixture of the milk the researchers could not determine whether the benefits were due to vitamin D3, calcium, or a combination of these plus other nutrients. They did state however that the results show a reduction in bone resorption in this elderly male population sample.
"Calcium-vitamin D3 fortified milk may represent an effective strategy to maintain bone strength by preventing bone loss and slowing the loss of cortical BMD in elderly men," concluded the researchers.
Some countries, like Canada, already fortify their milk and a 250 ml cup provides about 90 IU of vitamin D. In the UK, where milk is not fortified, a 250 ml cup contains only a trace of the vitamin.
The 1999 USDA survey on food intakes by individuals reported that less than 15 per cent of over-sixty year-old men were meeting their recommended daily intake of calcium.