B vitamins may play critical role in reducing epigenetic effects of air pollution

A new study by researchers at Columbia University's Mailman School of Public Health showed that B vitamins may play a critical role in reducing the impact of air pollution on the epigenome, further demonstrating the epigenetic effects of air pollution on health. This is the first study to detail a course of research for developing interventions that prevent or minimize the adverse effects of air pollution on potential automatic markers. The results are published online in the journal PNAS.

The study, conducted with colleagues at Harvard's T. H. Chan School of Public Health, in Sweden, China, Singapore, Mexico and Canada, reveals how individual-level prevention may be used to control the potential pathways underlying adverse effects of the particles PM2.5, particles with an aerodynamic diameter of <2.5 μm. These findings could have a significant public health benefit in regions of the world with frequent PM2.5 peaks.

"The molecular foundations of air pollution's health effects are not fully understood, and the lack of individual-level preventative options represented a critical knowledge gap," said Andrea Baccarelli, MD, PhD, professor and chair of Environmental Health Sciences at the Mailman School. "Our study launches a line of research for developing preventive interventions to minimize the adverse effects of air pollution on potential mechanistic markers. Because of the central role of epigenetic modifications in mediating environmental effects, our findings could very possibly be extended to other toxicants and environmental diseases."

The WHO estimates that 92 percent of the world's population currently lives in places where air quality levels exceed the WHO limits of 10 μg/m3.

Ambient PM2.5 pollution is one of the most prominent air pollutants because they deposit in the respiratory tract resulting in both lung and systemic inflammation and stress. While there has been substantial lowering of ambient PM2.5 achieved through large-scale emissions control policies over the past few decades, exposure peaks with adverse health consequences are still frequently recorded.

"The health effects of air pollution and how it plays a role in one's health raise many complex issues," said Jia Zhong, principal investigator, and postdoctoral research officer in the Department of Environmental Health Sciences. "Until we can attack the problem on an individual level we are a long way from fully tackling its challenges for the public's health."

The researchers administered one placebo or B-vitamin supplement (2.5 mg of folic acid, 50 mg of vitamin B6, and 1 mg of vitamin B12) daily to each adult recruited for the trial. To take part in the intervention, volunteers were required to be healthy non-smokers, 18 to 60 years old, who were not taking any medicines or vitamin supplements.

Plasma B vitamin measurements taken before and after placebo and supplementation showed that B-vitamin supplements significantly increased the median plasma concentrations of folic acid (56 nmol/L; IQR: 13; P = 0.02), vitamin B6 (428 nmol/L; IQR: 321; P = 0.004), and vitamin B12 (511 pmol/L; IQR: 85; P = 0.01). For those who took placebos for 4 weeks, their median plasma concentrations were similar: 39 nmol/L (IQR: 24 nmol/L) for folic acid (P = 0.82), 37 nmol/L(IQR: 18 nmol/L) for vitamin B6 (P = 0.75), and 262 pmol/L (IQR: 214 pmol/L) for vitamin B12 (P = 0.42). All exposure experiments were conducted at the same time of the day.

Ambient particles were drawn from an inlet next to a heavily trafficked street in downtown Toronto with more than 1000 vehicles passing through each hour. Particles were delivered via an "oxygen type" facemask. Blood samples were collected and measured using the Infinium Human Methylation 450K BeadChip.

"While emission control and regulation is the backbone of prevention, high exposures are, unfortunately, the rule still in many megacities throughout the world. As individuals, we have limited options to protect ourselves against air pollution. Future studies, especially in heavily polluted areas, are urgently needed to validate our findings and ultimately develop preventive interventions using B vitamins to contain the health effects of air pollution," said Dr. Baccarelli.