Increasing magnesium intake could increase bone density in the elderly andreduce the risk of osteoporosis, suggests a large American study.
"Higher Mg intake through diet and supplements was positively associatedwith total-body [bone mineral density] BMD in older white men and women. For every 100 mg per day increase in Mg, there was an approximate 2 per cent increase in whole-body BMD," said Kathryn Ryder and colleagues.
Osteoporosis is characterized by low bone mass, which leads to an increaserisk of fractures, especially the hips, spine and wrists. An estimated 10 million people suffer from osteoporosis in the US alone, while another 34m arebelieved to have low bone mass, which puts them at risk of developing thedisease.
Women are four times more likely to develop osteoporosis than men.
More than 2,000 volunteers aged 70 to 79 took part in the cross-sectional American study by completing a food-frequency questionnaire. All supplements anddietary intakes of magnesium were calculated from ingredients databases.
The authors did not identify the exact role of magnesium, but suggested itmay be via calciotropic hormones, by acting as a buffer against acidicWestern diets, or by substituting for calcium in the bones.
Magnesium intake was positively associated with BMD in white, but not black,men and women. These observations could be due to racial difference incalcium regulation or nutrient responses.
Dietary sources of magnesium include green, leafy vegetables, meats,starches, grains and nuts, and milk. Earlier dietary surveys show that alarge portion of adults do not meet the RDA for magnesium (320 mg per dayfor women and 420 mg per day for men).
Responding to this study, a spokesperson for the UK-based charity, the National OsteoporosisSociety, said: "Although there have been previous studies into the effectof magnesium on bone density, it is always encouraging to learn of studieswhich help build upon our knowledge of bone health."
"Some research has suggested that a low magnesium level may be a riskfactor for osteoporosis although magnesium deficiency is, in fact, very rarein humans. As yet there is no evidence that magnesium supplementationreduces fracture risk," she said.
For healthy bones the Society recommends a mixed, well-balanced calcium-rich diet and regular weight-bearing exercise.
The study was published in the Journal of the American GeriatricSociety (November, Vol 53, No 11, pp 1875-1880).