Recently, (June 2010) in the Journal of the American Medical Association the following study was posted:
 
JAMA. 2010 Jun 23;303(24):2486-94.
Effects of homocysteine-lowering with folic acid plus vitamin B12 vs placebo on mortality and major morbidity in myocardial infarction survivors: a randomized trial.
Abstract
CONTEXT: Blood homocysteine levels are positively associated with cardiovascular disease, but it is uncertain whether the association is causal. OBJECTIVE: To assess the effects of reducing homocysteine levels with folic acid and vitamin B(12) on vascular and nonvascular outcomes. DESIGN, SETTING, AND PATIENTS: Double-blind randomized controlled trial of 12,064 survivors of myocardial infarction in secondary care hospitals in the United Kingdom between 1998 and 2008. RESULTS: Allocation to the study vitamins reduced homocysteine by a mean of 3.8 micromol/L (28%).  CONCLUSION: Substantial long-term reductions in blood homocysteine levels with folic acid and vitamin B(12) supplementation did not have beneficial effects on vascular outcomes but were also not associated with adverse effects on cancer incidence.
PMID: 20571015 [PubMed - indexed for MEDLINE]
 
Immediately, health blogs and the media declared that lowering homocysteine levels did not lower the risk of cardiovascular disease.
 
This is a perfect example of misunderstanding a study's findings.
This study DID prove that, in established "Stage 4" cardiovascular disease (these patients had already had a myocardial infarction), lowering homocysteine, on average 28%, with 2mg of folic acid and 1mg of B12 did not prevent further vascular complications.
BUT, these patients had “Stage 4″ cardiovascular disease having already had an MI.  In patients with such firmly entrenched cardiovascular disease this study's findings may have no relevance at all about how lowering homocysteine may prevent PROGRESSION of cardiovascular disease in less severely affected patients.

For instance, in this study:
Arch Intern Med. 2009 Feb 23;169(4):335-41.
Folic acid, pyridoxine, and cyanocobalamin combination treatment and age-related macular degeneration in women: the Women’s Antioxidant and Folic Acid Cardiovascular Study.
RESULTS: After an average of 7.3 years of treatment and follow-up, there were 55 cases of AMD in the combination treatment group and 82 in the placebo group (relative risk, 0.66; 95% confidence interval, 0.47-0.93 [P = .02]). For visually significant AMD, there were 26 cases in the combination treatment group and 44 in the placebo group (relative risk, 0.59; 95% confidence interval, 0.36-0.95 [P = .03]). CONCLUSIONS: These randomized trial data from a large cohort of women at high risk of cardiovascular disease indicate that daily supplementation with folic acid, pyridoxine, and cyanocobalamin may reduce the risk of AMD.
PMID: 19237716 [PubMed - indexed for MEDLINE]
In this study: lowering homocysteine levels led to a lower risk of macular degeneration, IN THOSE WITHOUT ESTABLISHED DISEASE.
A similar benefit could be derived in cardiovascular disease - we already know high homocysteine levels increase the risk of stroke and Alzheimer’s.

Of note: The optimal way to lower homocysteine is by using l-methyl folate (the most bioavailable form of folic acid - 30% of the population has difficulty metabolizing folic acid into l-methyl folate - the actual active compound), methylcobalamin (B12), AND B6 (pyridoxal 5-phosphate is the most bioavailable form).

A "silver lining" that has not been discussed, is that no increased association with cancer was noted from chronic hypersupplementation of folic acid - there had been some concerns in previous studies indicating that in the metabolism of folic acid, there was an unintended consequence of increasing cancer occurrence.

Please address your homocysteine level.  Get tested - if high, treat aggressively with the aforementioned 3 components.

My prediction is that homocysteine will become the 'cholesterol' of the next decade.

All The Best,

MattinglyMD