Genetic factors explain about 80% of bone strength(1), however, bone mineral density (BMD) and bone metabolism are also affected by a number of environmental, hormonal and modifiable lifestyle factors, of which diet has been shown to play a prominent role(2). Oestrogen depletion that occurs during the menopause has a negative effect on BMD, putting post-menopausal women at a greater risk of low BMD or osteoporosis(3). The aim of this study was to compare intakes of macro- and micronutrients associated with bone health, between women with osteopenia and those with a normal BMD.
Post-menopausal women (n 300) (45–75 years) were recruited between October 2008 and June 2009. Nutrient intakes were estimated for 291 women from 4-d food diaries. BMD was measured in the first to fourth lumbar vertebrae (L1–L4) and left proximal femur by dual-energy X-ray absorptiometry.
Osteopenic women had significantly lower estimated dietary intakes of Ca, P and protein than those with normal BMD, with intakes of Ca below the UK reference nutrient intakes (RNI)(4) (Table 1). Spearman's rank analysis revealed a positive correlation between protein intake (g/d) and femoral BMD (r=0.02, P=0.041), albeit no relationship between dietary Ca or P and BMD was found. Both groups had median intakes of Mg and vitamin D below the RNI.
* RNI PM♀ Source: Dietary Reference Values for food Energy and Nutrients for the UK 1991.
† Significant difference between groups with normal and osteopenic BMD values as determined by Mann–Whitney U-test (P<0.05).
‡ For the population aged 65 or more only and for those aged 4–65 years who are at risk for inadequate UVB sunshine exposure.
§1 mg P: 1 mg Ca.
Osteopenia is defined as a BMD between 1 and 2.5 sd below that of young adults (T-score −1 to −2.5).
Osteopenia was associated with lower intakes of bone related nutrients among post-menopausal women in Northern Ireland. Vitamin D intake was low in both groups; suboptimal vitamin D intakes have been reported before in post-menopausal women in Ireland(5) and is an area for concern. Dietary advice to older women to optimise intakes of Ca, vitamin D and trace elements may have a beneficial effect on bone health.