A Human Intervention Trial: Effects of Fine Concentrated Ambient Particles on Cardiac Autonomic Dysfunction and Inflammation Are Mitigated by B Vitamin Supplementation

Abstract

Background: Ambient fine particulate matter (PM2.5) pollution is a trigger of acute cardiovascular events. Individual-level preventions have been proposed to complement regulation in reducing the global burden of PM2.5–related cardiovascular diseases. We investigated whether B vitamins mitigate the acute effects of PM2.5 on cardiac autonomic dysfunction and inflammation. Methods: In a single-blind crossover intervention trial, we administrated placebo and then four-week B vitamin supplement (5 mg/d folic acid, 100 mg/d vitamin B6, and 1 mg/d vitamin B12) to ten healthy volunteers. Each volunteer received three two-hour controlled exposure experiments to medical air or PM2.5 (250μg/m3), in pre-determined order. We used electrocardiogram to measure resting heart rate (HR) and heart rate variability (HRV), and hematology analyzer to determine white blood cell (WBC) counts (pre-, post-, 24 h post-exposure). Results: Compared to medical air, PM2.5 exposure was associated with 3.8 bpm (95% CI, 0.3, 7.4; P=0.04) higher resting HR and 57.5% (95% CI, 2.5%, 81.5%; P=0.04) lower low-frequency power following exposure. PM2.5 exposure was associated with 11.5% (95% CI, 0.3%, 24.0%; P=0.04) higher total WBC count and 12.9% (95% CI, 4.4%, 22.1%; P=0.005) higher lymphocyte count 24 h post-exposure. These effects were mitigated by B vitamin supplementation – which attenuated the effect of PM2.5 on HR by 150% (P=0.003), low-frequency power by 90% (P=0.01), total WBC count by 139% (P=0.006), and lymphocyte count by 106% (P=0.02). Conclusions: In healthy adults, two-hour PM2.5 exposure substantially increases HR, reduces HRV, and increases WBC. These effects are reduced by four-week B vitamin supplementation.