Folate improves endothelial function in patients with coronary heart disease

Area of Science:

• Cardiovascular Science
• Nutritional Biochemistry
• Endothelial Function Research

Background:

• Elevated plasma homocysteine is linked to cardiovascular risk, but causality is unproven.
• Folic acid administration lowers plasma total homocysteine (tHcy) but clinical cardiovascular benefit and optimal dosage remain unclear.
• Endothelial dysfunction is a key factor in coronary heart disease (CHD).

Purpose of the Study:

• To investigate the effect of folic acid on endothelial function in patients with established coronary heart disease (CHD).
• To explore the mechanisms underlying folic acid's impact on endothelial function, particularly its relationship with homocysteine levels and nitric oxide pathways.

Main Methods:

• Assessing endothelial function using flow-mediated dilatation (FMD) in the brachial artery of CHD patients.
• Administering oral folic acid (5 mg/day) and evaluating acute (2-4 hours post-dose) and chronic effects.
• Investigating the role of nitric oxide by administering 5-methyltetrahydrofolate intra-arterially and using monomethyl arginine (L-NMMA) as a blocker.

Main Results:

• Oral folic acid (5 mg/day) significantly enhanced endothelial function (FMD) and lowered homocysteine in CHD patients.
• Acute administration of folic acid led to rapid FMD improvement within 2-4 hours, preceding significant homocysteine reduction.
• Intra-arterial 5-methyltetrahydrofolate improved FMD, an effect inhibited by L-NMMA, indicating nitric oxide mediation.

Conclusions:

• Pharmacological doses of folic acid markedly enhance endothelial function in patients with CHD.
• The observed endothelial benefits of folic acid may be independent of its homocysteine-lowering effects.
• Folate's positive impact on endothelial function in CHD appears to be mediated by nitric oxide pathways.