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 .
Mineral water fortified with folic acid, vitamins B6, B12, D and calcium improves folate status and decreases plasma homocysteine concentration in men and women
Objective : We investigated the effects of mineral water fortified with folic acid , vitamins B6 , B12 , D and calcium on folate concentrations in serum and erythrocytes , serum vitamin B12 and plasma homocysteine concentrations in free-living subjects . In addition , we investigated the bioavailability of calcium added to mineral water by measuring urinary calcium excretion and serum alkaline phosphatase activity . Design : R and omized , controlled , double-blinded , parallel design . Setting : Outpatient dietary intervention with free-living subjects in Eastern Finl and .Subjects : Altogether , 66 subjects were recruited for the study . In all , 60 subjects completed the study . Interventions : The study began with a 2-week run-in period followed by an 8-week intervention period . During the intervention study , subjects consumed mineral water fortified with folic acid ( 563 μg/day ) , vitamins B6 ( 1 mg/day ) , B12 ( 7.5 μg/day ) , cholecalciferol ( 0.6 μg/day ) and calcium ( 563 mg/day ) or placebo mineral water . Results : The fortified mineral water increased serum and erythrocyte folate concentrations by 16.1±5.6 nmol/l ( P<0.001 ) and 199±76 nmol/l ( P<0.001 ) , respectively , and decreased plasma homocysteine concentration by 1.6 μmol/l ( P<0.001 ) . Urinary calcium excretion and serum alkaline phosphatase activity for 24 h increased significantly ( P<0.001 and P=0.01 respectively ) in the intervention group . Conclusions : Mineral water fortified with folic acid , vitamins B6 , B12 and D and calcium enhanced folate status and reduced plasma homocysteine concentration in normohomocysteinemic subjects without folate deficiency . Indirect measures of calcium and bone metabolism indicated that the calcium used in the fortification of the mineral water was bioavailable . Sponsorship : Olvi PLC , Iisalmi , Finl and
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 .