Increased ingestion of folic acid from supplements and fortified foods does not worsen health problems related to vitamin B12 deficiency, report researchers from the National Institutes of Health and other institutions (Mills JL et al. Am J
Clin Nutr. doi:10.3945/ajcn.111.014621 [published online ahead of print June 8, 2011]). Earlier studies, many conducted in older individuals, found that adults with low vitamin B12 blood levels who also had high folate blood levels had higher rates of anemia and other blood abnormalities—suggesting that folate exacerbates vitamin B12–related metabolic abnormalities.
Hampton T. Vitamin B12 Deficiency and Folate. JAMA. 2011;306(4):366. doi:10.1001/jama.2011.1011