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 .
Vitamin and mineral status of trained athletes including the effects of supplementation.
We measured serum concentrations of  thiamin , riboflavin  ,  nicotinic acid  ,  pyridoxine , folate , cyanocobalamin , ascorbic acid , retinol , tocopherol , zinc , magnesium , copper , iron , and ferritin as well as hemoglobin , hematocrit , percentage transferrin saturation , and total iron-binding capacity in athletes who ingested a multivitamin and mineral supplement for 3 mo . All blood variables were normal and except for pyridoxine and riboflavin there were no significant changes in the blood concentrations of any other vitamins or minerals measured . This may have been due to variable interactions between the vitamins and minerals in the supplement that prevented their being adequately absorbed . There were no signs or symptoms of serious toxic side effects . We conclude that multivitamin and mineral supplementation was without any measurable ergogenic effect and that such supplementation is unnecessary in athletes ingesting a normal diet
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 .