Pretreatment with 10 mg/d oral folic acid for 2 weeks prevented the acute fat load-induced decrease in flow-mediated dilatation seen with placebo (median FMD 9.9% vs 5.8%).
RCT (n=20)
placebo-controlled
randomized
Does oral folic acid prevent fat-induced endothelial dysfunction and oxidative stress in healthy volunteers?
Oral folic acid pretreatment prevents lipid-induced endothelial dysfunction and oxidative stress in healthy volunteers, suggesting potential vasculoprotective effects.
Absolute Event Rate: 9.9% vs 5.8%
Triglyceride-rich lipoproteins that circulate postprandially are increasingly being recognized as potentially atherogenic. These particles also have been shown to cause endothelial dysfunction. We recently demonstrated that acute parenteral administration of folic acid restores endothelial function in vivo in patients with increased LDL cholesterol levels. In vitro data suggested that this effect could be mediated by a reduction of radical stress. In the present study, therefore, we evaluated the effect of an acute oral fat load on both endothelial function and oxygen radical production. Next, we studied whether 2 weeks of pretreatment with 10 mg folic acid PO could prevent these fat-induced changes. We conducted a prospective, randomized, placebo-controlled study to evaluate the effect of oral folic acid administration (10 mg/d for 2 weeks) on basal endothelial function as well as endothelial function on an acute fat load in 20 healthy volunteers 18 to 33 years old. Endothelial function was assessed as flow-mediated dilatation (FMD). Endothelium-independent dilatation was measured after sublingual nitroglycerin spray. Oxygen radical stress was assessed by measurement of the urinary excretion of the stable radical-damage end product malondialdehyde. During administration of placebo, FMD decreased significantly after an acute oral fat load, with a median from 10.6% (8.3% to 12.2%) to 5.8% (3.0% to 10.2%), P<0.05. During folic acid administration, FMD was unaffected by a fat load, with a median from 9.6% (7.1% to 12.8%) to 9.9% (7.5% to 14.1%), P=NS. The increase in malondialdehyde excretion in the urine after fat loading was also prevented during folic acid administration (absolute increase after an acute fat load during placebo, 0.11+/-0.1 micromol/L versus folic acid, 0.02+/-0.1 micromol/L, P<0.05). The response to the endothelium-independent vasodilator nitroglycerin remained unaltered throughout the study. Pretreatment with oral folic acid prevents the lipid-induced decrease in FMD as well as the lipid-induced increase in urinary radical-damage end products. Because these observations were made in healthy volunteers with normal folate and homocysteine levels, it is suggested that a higher folate intake in the general population may have vasculoprotective effects.
Wilmink et al. (Sat,) conducted a rct in healthy volunteers (n=20). folic acid vs. placebo was evaluated on Endothelial function assessed as flow-mediated dilatation (FMD) after an acute oral fat load. Pretreatment with 10 mg/d oral folic acid for 2 weeks prevented the acute fat load-induced decrease in flow-mediated dilatation seen with placebo (median FMD 9.9% vs 5.8%).