CONCLUSIONS Dietary calcium intake is not associated with risk of fracture , and there is no clinical trial evidence that increasing calcium intake from dietary sources prevents fractures .
OBJECTIVE To examine the evidence underpinning recommendations to increase calcium intake through dietary sources or calcium supplements to prevent fractures .
False alarms and pseudo-epidemics: the limitations of observational epidemiology.
Most reported associations in observational clinical research are false , and the minority of associations that are true are often exaggerated . This credibility problem has many causes , including the failure of authors , review ers , and editors to recognize the inherent limitations of these studies . This issue is especially problematic for weak associations , variably defined as relative risks ( RRs ) or odds ratios ( ORs ) less than 4 . Such associations , commonly reported in the medical literature , are more likely to be attributable to bias than to causal association . All observational research has bias ( which can include selection , information , and confounding bias ) . Hence , detection of small associations falls below the discriminatory ability of observational studies . In general , unless RRs in cohort studies exceed 2 to 3 or ORs in case-control studies exceed 3 or 4 , associations in observational research findings should not be considered credible . However , these guidelines are not foolproof : strong ( yet spurious ) associations can result when large amounts of bias are present . Only in a properly performed r and omized controlled trial , free of bias , should small associations merit attention . Better training and more circumspection on the part of investigators , tougher editorial st and ards on the part of journals , and hefty skepticism on the part of referees and readers are necessary to avoid the dangers of false alarms , pseudo-epidemics , and their unfortunate consequences
CONCLUSIONS Dietary calcium intake is not associated with risk of fracture , and there is no clinical trial evidence that increasing calcium intake from dietary sources prevents fractures .
OBJECTIVE To examine the evidence underpinning recommendations to increase calcium intake through dietary sources or calcium supplements to prevent fractures .