Fractures may become less likely with supplement regimens that use calcium and vitamin D, but vitamin D supplements alone have not been shown to reduce risk, according to findings published in JAMA Network Open.
“Combined supplementation with 800 IU/day vitamin D and 1200 mg/day calcium has been recommended for prevention of fractures in older adults living in institutions and in those with low vitamin D status,” Robert Clarke, MD, professor of epidemiology and public health medicine at the University of Oxford, told Healio. “However, previous trials and meta-analyses of vitamin D alone or in combination with calcium for prevention of fracture in either community-dwelling or general population settings reported conflicting results, with some reporting protective effects against fractures, but others demonstrated no beneficial effects.”
Clarke and colleagues found that fracture risk fell by 7% when 25-hydroxyvitamin D levels rose by 10 ng/mL (RR = 0.93; 95% CI, 0.89-0.96) based on calculations from a meta-analysis of 11 observational studies. The results also indicated that hip fracture risk fell by 20% when 25-(OH)D levels rose by 10 ng/mL (RR = 0.8; 95% CI, 0.75-0.86).
“The present meta-analysis of the observational studies of blood 25-(OH)D concentration and risk of fracture demonstrated that higher blood 25-(OH)D concentrations were associated with lower risks of any fracture and hip fracture,” the researchers wrote.
Fractures may become less likely with supplement regimens that use calcium and vitamin D, but vitamin D supplements alone have not been shown to reduce risk.
Despite this finding, the researchers noted that overall fracture risk and hip fracture risk were unaffected by vitamin D supplements vs. placebo when they conducted a meta-analysis of 11 randomized clinical trials in which “placebo or no treatment” was used as the control.
“The results demonstrated that treatment with vitamin D alone had no significant effects on risk for any fracture or hip fracture,” Clarke said. “However, interpretation of the results of these trials was constrained by their small sample size, short duration of treatment, high risk of bias — chiefly due to incomplete ascertainment of outcomes — intermittent dosing regimens of vitamin D and failure to achieve adequate differences in vitamin D concentrations.”
The researchers found that fracture risk was cut by 6% with a combination of calcium and vitamin D (RR = 0.94; 95% CI, 0.89-0.99) based on a meta-analysis of six randomized clinical trials in which “placebo or no treatment” was used as the control. In addition, the meta-analysis revelated that hip fracture risk fell by 16% with the supplement combination (RR = 0.84; 95% CI, 0.72-0.97). Clarke said that “the beneficial effects of combined supplements of calcium and vitamin D were greater in high-risk older people with low blood levels of vitamin D or who were living in institutions.”
“Concerns have been raised about the safety of combining calcium and vitamin D for cardiovascular disease and higher risks of kidney stones associated with calcium supplements,” the researchers wrote. “Further large randomized clinical trials of vitamin D plus calcium are needed among older individuals with frailty or among other high-risk groups with low vitamin D status to clarify the relevance of combined treatment of vitamin D plus calcium for prevention of hip and other fragility fractures.” – by Phil Neuffer
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Robert Clarke, MD, can be reached at email@example.com.
Disclosures: Clarke reports no relevant financial disclosures. Please see the study for all other authors’ relevant financial disclosures.