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 dietary patterns on serum homocysteine: results of a randomized, controlled feeding study.
BACKGROUND Elevated blood levels of homocysteine are associated with an increased risk of atherosclerotic cardiovascular disease . Although numerous studies have assessed the impact of vitamin supplements on homocysteine , the effect of dietary patterns on homocysteine has not been well studied . METHODS AND RESULTS During a 3-week run-in , 118 participants were fed a control diet , low in fruits , vegetables , and dairy products , with a fat content typical of US consumption . During an 8-week intervention phase , participants were then fed 1 of 3 r and omly assigned diets : the control diet , a diet rich in fruits and vegetables but otherwise similar to control , or a combination diet rich in fruits , vegetables , and low-fat dairy products and reduced in saturated and total fat . Between the end of run-in and intervention periods , mean change in homocysteine was + 0.46 micromol/L in the control diet , + 0.21 micromol/L in the fruits and vegetables diet ( P=0.47 compared with control ) , and -0.34 micromol/L in the combination diet ( P=0.03 compared with control , P=0.12 compared with the fruits and vegetables diet ) . In multivariable regression models , change in homocysteine was significantly and inversely associated with change in serum folate ( P=0.03 ) but not with change in serum vitamin B(12 ) ( P=0.64 ) or pyridoxal 5 ' phosphate , the coenzyme form of vitamin B(6 ) ( P=0.83 ) . CONCLUSIONS Modification of dietary patterns can have substantial effects on fasting levels of total serum homocysteine . These results provide additional insights into the mechanisms by which diet might influence the occurrence of atherosclerotic cardiovascular disease
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 .