Vitamin B Supplementation, Homocysteine Levels, and
the Risk of Cerebrovascular Disease
A meta-analysis published in Neurology indicates that Vitamin B supplementation to lower homocysteine levels significantly reduces the incidence of stroke events.
Objective: To perform a meta-analysis on the effect of lowering homocysteine levels via B vitamin supplementation on cerebrovascular disease risk.
Methods: Using clinical trials published before August 2012 to assess stroke events, we used relative risks (RRs) with 95% confidence intervals (95% CIs) to measure the association between B vitamin supplementation and endpoint events using a fixed-effects model and χ2 tests. We included 14 randomized controlled trials with 54,913 participants in this analysis.
Results: We observed a reduction in overall stroke events resulting from reduction in homocysteine levels following B vitamin supplementation (RR 0.93; 95% CI 0.86–1.00; p = 0.04) but not in subgroups divided according to primary or secondary prevention measures, ischemic vs hemorrhagic stroke, or occurrence of fatal stroke.
There were beneficial effects in reducing stroke events in subgroups with ≥3 years follow-up time, and without background of cereal folate fortification or chronic kidney disease (CKD). Some trials that included CKD patients reported decreased glomerular filtration rate with B vitamin supplementation.
We conducted detailed subgroup analyses for cyanocobalamin (vitamin B12) but did not find a significant benefit regarding intervention dose of vitamin B12 or baseline blood B12 concentration.
Stratified analysis for blood pressure and baseline participant medication use showed benefits with >130 mm Hg systolic blood pressure and lower antiplatelet drug use in reducing stroke risk.
Conclusions: B vitamin supplementation for homocysteine reduction significantly reduced stroke events, especially in subjects with certain characteristics who received appropriate intervention measures.
- Yan Ji, MD,
- Song Tan, MD,
- Yuming Xu, MD,
- Avinash Chandra, MD,
- Changhe Shi, MD,
- Bo Song, MD,
- Jie Qin, MD and
- Yuan Gao, MD
Vitamin B-12 Fact Sheet
The Top 10 Foods Highest In Vitamin B-12
People with a genetically determined, reduced breakdown of the amino acid homocysteine have an increased risk of coronary heart disease compared to healthy people. This is revealed in doctoral research carried out by Mariska Klerk at Wageningen University.
The researchers from Wageningen have demonstrated that people with a genetically determined, specific form of reduced homocysteine breakdown have a 16 percent higher risk of developing coronary heart disease. People with the aforementioned reduced breakdown have on average a 25 percent higher homocysteine concentration in their blood from birth onwards, compared to other people.
Homocysteine has been associated with cardiovascular disease for a long time. However, until recently it was not clear whether an increased concentration of this amino acid in the blood was the cause or consequence of cardiovascular disease. This research into people with a genetic predisposition for a high homocysteine concentration in the blood supports the argument that this high concentration is a cause of cardiovascular disease.
Homocysteine is an amino acid (protein building block) which is formed in the body during the breakdown of another amino acid (methionine) obtained from food. The body regulates the homocysteine concentration in the blood with the aid of several B vitamins, including folic acid. Apart from a genetic predisposition, a shortage of these vitamins can also lead to an increased concentration of homocysteine in the blood. Folic acid supplementation is therefore an effective strategy to reduce the quantity of homocysteine in the blood.
The research has also revealed that people with genetically determined, reduced homocysteine breakdown only had an increased risk of heart disease when the folic acid concentration in the blood was low. This result suggests that reducing the homocysteine concentration in the blood by means of folic acid supplementation will reduce the incidence of cardiovascular disease.
The researchers also investigated whether a reduction in the homocysteine concentration in the blood as a result of vitamin B supplementation had a favourable effect on blood clotting in healthy volunteers. The assumption was that homocysteine increases the risk of cardiovascular disease by overstimulating blood clotting (which could eventually result in thrombosis). Despite a considerable reduction in the homocysteine concentration in the blood of people who had received extra vitamin B, no clear effect on blood clotting could be demonstrated.
The research was funded by the Netherlands Organisation for Scientific Research (NWO).