The role of folic acid and homocysteine in pregnancy is becoming clearer. The efforts of many countries to prevent neural tube defects through public awareness of folic acid have been disappointing, but evidence is now emerging that the food fortification programs in the United States and Canada are effective in reducing the numbers of neural tube defects, and there may be additional benefits in terms of other congenital defects such as oral-facial clefts and congenital heart disease. Homocysteine has a significant association with vascular disease in later life, is elevated in preeclampsia, and has been associated with other pregnancy complications such as early pregnancy loss. The data from cohorts of women with a history of preeclampsia during pregnancy indicate that they are at increased risk for cardiovascular and cerebrovascular disease in later life. Elevated homocysteine concentrations may be a common link that accounts for these associations.
Mandatory folic acid (FA) food fortification has been introduced in various countries, with the primary aim of preventing neural tube defects. It has been proposed that the inclusion of vitamin B12 together with FA may provide added health benefits and alleviate the problem of 'masking' of vitamin B12 deficiency by FA in the elderly (1)(2) . However, the response to supplementation with vitamin B12 at low doses has not been sufficiently investigated to date. The aim of the current study was to establish the minimum effective dose of vitamin B12 required to optimise B12 status and lower homocysteine.A 27-week, double-blinded, placebo controlled dose-response trial was conducted. Participants (n 231), healthy younger and older adults, initially took folic acid (400 mg/day) for 11 weeks for repletion of folate status (the main determinant of homocysteine), and were then stratified according to homocysteine concentrations and randomised to receive one of the four treatments for 16 weeks: folic acid + placebo; folic acid + 3 mg/day B12; folic acid + 10 mg/day B12; folic acid + 50 mg/day B12. An analysis of the B12 supplements at each dose was conducted in order to confirm their actual vitamin B12 content. The results showed a progressive increase in the serum vitamin B12 response to increasing doses of B12. Concentrations of methylmalonic acid (MMA), a specific functional biomarker of vitamin B12 status, were lowered by 13 % and reached a plateau with a B12 dose of 3.4 mg/day; higher doses did not result in significant further lowering. A homocysteine lowering effect of 4 % was achieved in response to intervention with vitamin B12 (over and above the observed response to FA) however this was not significant at any B12 dose.The current study demonstrates that long term intervention with low doses of vitamin B12 in healthy younger and older adults results in improved B12 status as evidenced by increased serum vitamin B12 and reduced serum MMA concentrations. The maximal response of MMA was achieved in response to supplementation with 3.4 mg/day vitamin B12 in addition to the average dietary B12 intake of 4.0 mg/day estimated in this cohort. These findings will be of relevance to emerging dietary vitamin B12 recommendations in that they suggest that a daily intake of around 7 mg/day B12 may be considered adequate for optimising functional status of vitamin B12.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.