Studies of biomarker responses to intervention with vitamin B-12: a systematic review of randomized controlled trials.
Hoey, L., Strain, J.J., and McNulty, H. Am J Clin Nutr – 01-JUN-2009; 89(6): 1981S-1996S
Objectives: To assess the effectiveness of various biomarkers of Vitamin B12 status in randomized controlled trials of oral B12 supplementation.
Methods: A systematic meta-analysis of the literature was undertaken. A structured search strategy on Ovid MEDLINE, EMBASE (Ovid), and Cochrane databases was implemented using formal inclusion/exclusion criteria, data extraction and validity assessment. Eight randomized, controlled trials were included. All trials measured serum and plasma values of B12. In addition, three studies followed methylmelonic acid values and six studies followed total homocysteine levels with B12 supplementation.
Results: The three biomarkers studied, Vitamin B12, methylmelonic acid and total homocysteine, correlated with levels of Vitamin B12 intake (P< .0001). Insufficient data was available to determine the effectiveness of holotranscobalamin as a marker.
Conclusions: The three biomarkers are effective measures of Vitamin B12 intake, particularly in those patient populations with borderline or low plasma/serum B12 levels. Future supplementation trials with Vitamin B12 should measure the holotranscobalamin response.