A new study published in the New England Journal of Medicine revealed that smoking cigarettes is way worse for your health than researchers had previously thought. Smoking apparently causes five additional diseases which previously had not been linked to tobacco use.

The study followed upwards of a million people over the course of ten years, tracking the number of deaths, diseases, and health fluctuations of its participants. Via the NEJM:

We pooled data from five contemporary U.S. cohort studies including 421,378 men and 532,651 women 55 years of age or older. Participants were followed from 2000 through 2011, and relative risks and 95% confidence intervals were estimated with the use of Cox proportional-hazards models adjusted for age, race, educational level, daily alcohol consumption, and cohort.

What the study found after ten years was that "approximately 17% of the excess mortality among current smokers was due to associations with causes that are not currently established as attributable to smoking." Smoking had been linked to 12 different kinds of cancer and a number of other diseases, but the study found at least five new diseases caused or made worse by cigarettes. From the New York Times:

In addition to the well-known hazards of lung cancer, artery disease, heart attacks, chronic lung disease and stroke, the researchers found that smoking was linked to significantly increased risks of infection, kidney disease, intestinal disease caused by inadequate blood flow, and heart and lung ailments not previously attributed to tobacco.

For ethical reasons, the researchers couldn't force people to smoke for a study, so their study isn't "considered as strong as experiments in which participants are assigned at random to treatments or placebos and then compared," as the Times put it. But scientists involved in the study defended their research, noting that cigarette use tends to worsen or exacerbate illnesses.

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