RESULTS The meta- analysis of observational studies showed a weaker slope of dose-response relations than the meta- analysis of RCTs .
The obtained dose-response estimate between vitamin B-12 intake and status provides complementary evidence to underpin recommendations for a vitamin B-12 intake of population
BACKGROUND Many r and omized controlled trials ( RCTs ) and observational studies have provided information on the association between vitamin B-12 intake and biomarkers .
The use of these data to estimate dose-response relations provides a useful means to summarize the body of evidence .
OBJECTIVE We systematic ally review ed studies that investigated vitamin B-12 intake and biomarkers of vitamin B-12  status and estimated dose-response relations with the use of a meta- analysis .
A randomized, double-blind, placebo-controlled study of oral vitamin B12 supplementation in older patients with subnormal or borderline serum vitamin B12 concentrations.
OBJECTIVES To determine the effect of small doses of oral cyanocobalamin supplements in older patients with low or borderline serum vitamin B12 concentrations but no other evidence of pernicious anemia ( PA ) . DESIGN R and omized , double-blind , placebo-controlled study assessing the efficacy of oral cyanocobalamin 10 microg and 50 microg daily for 1 month . SETTING Two geriatric hospitals in the North Western Health Care Network , Melbourne , Australia . PARTICIPANTS Thirty-one in patients with serum vitamin B12 levels between 100 and 150 pmol/L , without PA , other malabsorption disorders , or progressive neurological or terminal illness . The mean age was 81.4 years . INTERVENTION After informed consent , a medical and drug history was taken and the Mini-Mental State Examination ( MMSE ) completed . A dietitian made assessment of oral cobalamin intake . Blood was taken for serum vitamin B12 , serum and red cell folate assay , full blood examination , fasting serum gastrin , parietal and intrinsic factor antibodies , fasting serum homocysteine , and creatinine . Patients were then r and omized to receive 10 microg oral cyanocobalamin , 50 microg oral cyanocobalamin , or placebo treatment for 1 month , after which the investigations and clinical examinations were repeated . MEASUREMENTS Percentage change in the level of vitamin B12 , homocysteine , folate , and red cell parameters and absolute changes in MMSE were calculated and compared between groups . The groups were compared on the number of responders who improved their level of B12 by 20 % . Chi-square calculations on changes in serum vitamin B12 concentration were also performed . RESULTS Mean serum vitamin B12 + /- st and ard deviation improved by 51.7 + /- 47.1 % in the 50-microg group , 40.2 + /- 34.4 % in the 10-microg group , and 11.7 + /- 24.5 % in the placebo group . The change in the 50-microg cyanocobalamin group was significantly greater than that in the placebo group ( P=.044 ) . The change in the 10-microg cyanocobalamin group was not significantly different from that in the placebo group ( P=.186 ) . Eight of 10 subjects in each treatment group were classified as responders , compared with two of 11 in the placebo group ( P=.004 ) . Homocysteine levels fell in patients receiving cyanocobalamin , but this fall failed to reach statistical significance . There were no significant changes in the other parameters measured . CONCLUSION Cyanocobalamin supplementation of 50 microg but not 10 microg daily produced a significant increase in serum vitamin B12 . This result has implication s for the management of patients with subnormal or borderline serum vitamin B12 concentrations and for food fortification with vitamin B12
RESULTS The meta- analysis of observational studies showed a weaker slope of dose-response relations than the meta- analysis of RCTs .
The obtained dose-response estimate between vitamin B-12 intake and status provides complementary evidence to underpin recommendations for a vitamin B-12 intake of population
BACKGROUND Many r and omized controlled trials ( RCTs ) and observational studies have provided information on the association between vitamin B-12 intake and biomarkers .
The use of these data to estimate dose-response relations provides a useful means to summarize the body of evidence .
OBJECTIVE We systematic ally review ed studies that investigated vitamin B-12 intake and biomarkers of vitamin B-12  status and estimated dose-response relations with the use of a meta- analysis .