Recent evidence from the NORVIT trial suggests an increased risk of adverse cardiac events in patients receiving vitamin B6 supplementation in combination with folic acid and B12. An anti-angiogenic effect of B6 supplementation was proposed as one possible explanation for the observed results. Therefore, we hypothesized that supplementation with vitamin B6 alone would result in an impaired angiogenic response to ischemia, that would be reflected in reduced blood flow and endothelial progenitor cell (EPC) numbers, and that this effect would be enhanced when B6 was provided with B12 and folate. Male Sprague Dawley rats (280-300g) were randomly assigned to one of three diet groups: Control (CON)(7 mg/kg diet vitamin B6) (n=20), High B6 (HB6) (35 mg/kg/diet B6) (n=14) and a tri-vitamin group (TV)(B6-35mg/kg, B12-358μg/kg and Folic Acid-3.6mg/kg diet)(n=17). Following five weeks of diet therapy, animals underwent ligation of the left common iliac artery. Subsequently, the angiogenic response was monitored at day 1 and at day 35 using contrast enhanced ultrasound (CEU) to assess tissue perfusion. The number of circulating EPCs as a percentage of the white cell mononuclear fraction was determined using FACS. Animals in each treatment group had similar food intakes and rates of weight gain throughout the experimental period. No differences in blood flow were observed between treatments on day one post ischemia (p=0.9). At day 35 post ischemia, CEU perfusion revealed a significant improvement in microvascular blood flow in both HB6 and CON animals (p=0.004 & p<0.001 respectively). However, the improvement in blood flow was significantly larger in CON in comparison with HB6 (p=0.02). In contrast, blood flow in TV animals showed no improvement over the study period (p=0.9) and was significantly lower than CON (p=0.002) but not HB6 (p=0.09). EPC numbers were significantly reduced in TV animals but not B6 supplemented animals alone in comparison with CON (p=0.01 & p=0.15 respectively). These results suggest that both vitamin B6 supplementation alone or in combination with B12 and folate resulted in an impaired adaptive angiogenic response following ischemia resulting in reduced tissue perfusion and reduced circulating EPC numbers.

Participants will understand the components of an aggressive dietary strategy that can be used by patients to reduce cardiovascular risk factors.