Smokers who quit have metabolite levels that resemble those of nonsmokers

By American Chemical Society —— Bio and Archives September 25, 2017

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Even after years of smoking, the body has a remarkable ability to repair itself. Now in a study appearing in ACS' Journal of Proteome Research, scientists report that certain metabolic changes occur soon after quitting, and these changes could help explain how some ill-effects of smoking might be reversible. Smoking kills more than 7 million people worldwide annually and is one of the most important risk factors for six of world's eight leading causes of premature death, according to the World Health Organization. But soon after a person quits, the body begins to repair some of accumulated damage caused by smoking. In fact, according to the U.S. Centers for Disease Control and Prevention, within two to three months of quitting, lung function begins to improve and the risk of heart attack begins to diminish. A previous study published in 2013 suggested that metabolic changes that occur after smoking cessation may kick start these physiological improvements. Building on this work, Nikola Pluym and colleagues sought to hone in on what alterations smoking causes in the body's metabolic pathways and whether any of these changes are reversible after quitting.

The researchers regularly collected blood, urine and saliva samples from male volunteers, who were trying to quit smoking, up to three months after smoking cessation. To minimize nutritional effects on metabolism, the researchers strictly controlled the volunteers' diets during four in-patient stays. To ensure compliance, they measured levels of carbon monoxide and cotinine, a nicotine metabolite which can be detected in urine and saliva over several days after someone has smoked. In the study, the researchers analyzed the experimental samples with an untargeted metabolic fingerprinting approach. Overall, the researchers identified 52 metabolites that were significantly altered after the subjects stopped smoking, including several that showed reversible changes toward that of a nonsmoker's metabolic profile. The team concluded that these compounds could one day be used as biomarkers for smoking-induced biological changes. Moreover, the researchers state that the published method would be also useful for evaluating the benefits, if any, for smokers when switching to new products like electronic cigarettes. The authors acknowledge funding from Imperial Brands PLC and Analytcish- biologisches Forschungslabor (ABF) GmbH. In the paper, the authors state, "There has not been any influence on the work or publication by the sponsor Imperial Brands plc." "Metabolic Fingerprinting in Various Body Fluids of a Diet-Controlled Clinical Smoking Cessation Study Using a Validated GC-TOF-MS Metabolomics Platform"