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 .
Multivitamin-mineral supplementation: effects on blood chemistries of college-age women.
Forty-two female college students , age 18 - 29 yr . and consuming nutritionally balanced meals in the college cafeteria participated . Subjects discontinued all vitamin-mineral supplements ( VMS ) for 17 days and were r and omly assigned to one of two treatments , either a placebo , or VMS supplying the United States Recommended Daily Allowance ( USRDA ) of all vitamins , zinc , iron , iodine , copper , and 60 % of the USRDA of calcium , 50 % of magnesium and 45 % of phosphorus . Treatments were consumed for 77 days . Fasting pre- and post-treatment blood chemistries were compared . VMS yielded significant increases ( p less than 0.05 ) in serum vitamin B-12 ( + 25.05 pg/ml ) , vitamin C ( + 0.35 mg/dl ) and folate ( + 7.40 ng/ml ) . No significant changes ( p greater than 0.05 ) in hematological or other blood chemistries were observed . Significant decreases in the number of below-normal serum indicators of vitamin status ( p less than 0.05 ) and iron status ( p less than 0.005 ) were seen with VMS . No significant changes were seen with placebo ( p greater than 0.05 )
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 .