The average rates out of BMD reduction in earlier post-menopausal girls is focused on step one% a-year
We incorporated 59 randomised regulated trials and you can analyzed the effects off each other diet calcium source and you may calcium on BMD within four skeletal internet sites and also at three time circumstances. How big this new opinion allowed an assessment of one’s effects to your BMD of different resources of calcium supplements-weight loss present otherwise pills-as well as the effects for the very important subgroups such as those defined because of the serving out-of calcium supplements, usage of co-given vitamin D, and you will baseline health-related functions. The outcomes was in line with the individuals of an early on meta-investigation off fifteen randomised controlled trials out-of calcium supplements, which claimed a rise in BMD of just one.6-2.0% over two to four ages.72
An important restrict would be the fact BMD is only good surrogate to have the latest logical consequence of break. I undertook brand new opinion, yet not, as a few of the subgroup http://www.datingranking.net/es/los-mejores-sitios-de-citas analyses regarding the dataset off products which have fracture since an endpoint have limited strength,ten and you may a comparison anywhere between randomised regulated trials out-of weightloss offer of calcium and you may calcium supplements having break as endpoint was not possible since only several short randomised managed examples out of losing weight resources of calcium supplements reported crack analysis.10 Various other restrict is that inside 60% of the meta-analyses, statistical heterogeneity between the education is actually highest (I dos >50%). This indicates substantial variability throughout the results of provided products, although this try usually by visibility regarding a small amount of outlying show. Subgroup analyses fundamentally don’t dramatically clean out otherwise give an explanation for heterogeneity. I made use of arbitrary effects meta-analyses you to definitely just take heterogeneity into consideration, as well as their results will likely be translated because the reflecting the common effect along side set of products.
Implications from findings
The absence of one interaction which have baseline weight-loss calcium consumption otherwise a serving-reaction family suggests that growing intake thanks to fat loss provide otherwise by way of drugs does not best a dietary insufficiency (in which particular case greater outcomes is observed in people with a reduced intakes and/or higher dosage). An option options would be the fact increasing calcium intake has a weak anti-resorptive effect. Calcium supplements lose indicators out-of limbs formation and you will resorption because of the from the 20%,62 65 73 and you will growing dairy intake including minimizes bone turount.74 Suppression from bones turount might lead to the small noticed develops inside BMD.
Increases in BMD of about 1-2% over one to five years are unlikely to translate into clinically meaningful reductions in fractures. So the effect of increasing calcium intake is to prevent about one to two years of normal BMD loss, and if calcium intake is increased for more than one year it will slow down but not stop BMD loss. Epidemiological studies suggest that a decrease in BMD of one standard deviation is associated with an increase in the relative risk of fracture of about 1.5-2.0.75 A one standard deviation change in BMD is about equivalent to a 10% change in BMD. Based on these calculations, a 10% increase in BMD would be associated with a 33-50% reduction in risk of fracture. Therefore, the 1-2% increase in BMD observed with increased calcium intake would be predicted to produce a 5-10% reduction in risk of fracture. These estimates are consistent with findings from randomised controlled trials of other agents. The modest increases in BMD with increased calcium intake are smaller than observed with weak anti-resorptive agents such as etidronate76 and raloxifene.77 Etidronate, however, does not reduce vertebral or non-vertebral fractures, and raloxifene reduces vertebral but not non-vertebral fractures.78 In contrast, potent anti-resorptive agents such as alendronate, zoledronate, and denosumab increase BMD by 6-9% at the spine and 5-6% at the hip over three years.79 80 81 82 These changes are associated with reductions of 44-70% in vertebral fracture, 35-41% in hip fracture, and 15-25% in non-vertebral fractures.78 The magnitude of fracture reduction predicted by the small increases in BMD we observed with increased calcium intake are also consistent with the findings of our systematic review of calcium supplements and fracture.10 We observed small (<15%) inconsistent reductions in total and vertebral fracture overall but no reductions in fractures in the large randomised controlled trials at lowest risk of bias and no reductions in forearm or hip fractures.