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 .
Effect of supplementation with cobalamin carried either by a milk product or a capsule in mildly cobalamin-deficient elderly Dutch persons.
BACKGROUND A high prevalence of cobalamin deficiency occurs in the elderly population , which may be treated orally or with injections . Little is known about the relative bioavailability of crystalline cobalamin added to food products . OBJECTIVE The objective was to assess the effect of supplementation with 1000 microg crystalline cobalamin , carried either by a milk product or a capsule , on cobalamin status in mildly cobalamin-deficient elderly Dutch persons . DESIGN Two double-blind r and omized controlled intervention studies , each covering a 12-wk supplementation period , were carried out in parallel . Mildly cobalamin-deficient elderly persons ( n = 112 ) were separately recruited for the milk and capsule trials . Mild cobalamin deficiency was defined as a cobalamin concentration between 100 and 300 pmol/L and a plasma methylmalonic acid ( MMA ) concentration > or = 0.30 micromol/L. Allocation to the placebo or cobalamin carrier was carried out independently in both trials . RESULTS In the fortified-milk group , the mean ( + /-SD ) increase in serum cobalamin was 250 + /- 96 pmol/L , the median ( 5th and 95th percentiles ) decrease in plasma MMA was 0.19 ( -0.76 , -0.04 ) micromol/L , and the median decrease in plasma homocysteine was 4.0 ( -7.3 , 3.0 ) micromol/L. All changes were significantly different from those in the placebo milk group ( P < 0.01 ) . Likewise , in the cobalamin-capsule group , the mean increase in serum cobalamin was 281 + /- 136 pmol/L , the median decrease in plasma MMA was 0.18 ( -2.95 , 0.14 ) micromol/L , and the median decrease in plasma homocysteine was 1.8 ( -10.6 , 2.4 ) micromol/L ; all changes were significantly different from those in the placebo capsule group ( P < 0.01 ) . No significant differences were observed between the fortified-milk and capsule groups ( P > 0.40 ) . CONCLUSION Crystalline cobalamin added to milk is an effective alternative to cobalamin capsules for improving cobalamin status
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 .