A few weeks ago a tweet showed up in my Twitter stream: “Within a few days of quitting #smoking, your sense of smell gets better.”
Despite being sent by the National Institutes of Health Office of Disease Prevention, this claim immediately set off the alarm on the FirstNerve Bogosity Meter. I’ve followed the scientific literature on smoking and olfaction for many years and could recall no such result.
Hoping for enlightenment, I followed the @NIHprevents link to a page at smokefree.gov called “What Happens to Your Body After You Quit?” There I found this:
Within a few days you may notice other things.Somehow I had expected more content from NIH. So I goosed them with my own tweet: “Really? Evidence would be nice. None cited at ur link.” Two days later I got a reply: “@theNCI [the National Cancer Institute] forwarded to us the following study to share with you http://1.usa.gov/1dO37Gu”
Your senses of taste and smell are better.
The NCI link was to a paper on PubMed that I know very well, a study published by Dick Doty and his colleagues in JAMA back in 1990. They gave the UPSIT smell test to 638 people with detailed smoking histories. They found reduced odor identification ability in long-term smokers, an effect that increased the more a person smoked. They also found that the effect was reversible.
So does this support the NIH claim that a smoker’s sense of smell will improve “within a few days” of quitting? Hardly.
The paper quantified smoking history in pack-years, calculated as the number of packs smoked per day multiplied by the number of years of smoking. The results of smoking and quitting are discussed exclusively in terms of pack-years, not days or even weeks. So NIH and NCI seem to have pulled the “after a few days” claim out of thin air.
More troubling is what the JAMA authors say about the effects of quitting:
While improvement in smell function appears to occur following cessation of smoking, such improvement is not rapid (eg, for a two-pack-per-day smoker, restoration of smell function to a level observed in non-smokers requires approximately the same number of years as the number of years smoked. [Emphasis mine.]Contrary to claims by the anti-smoking activists at NCI and the NIH Office of Disease Prevention, there is no evidence in this paper that smell function improves “within a few days” of quitting. In fact, that claim is at odds with the JAMA authors’ own conclusion.
I tweeted the relevant passage to @NCI and @NIHprevents with a comment: “Did you not read the paper? Or are you lying in the service of a higher cause?”
I also wrote: “No improved smell ‘within a few days’ of quitting. Suggest you retract misleading claim.”
I have yet to get a response.
This episode illustrates a disturbing trend—the bending of science in the promotion of public policy objectives. While encouraging people to quit smoking may be a noble and high-minded policy goal, it does not justify mischaracterizing the scientific literature. And twisting science is the last thing that the National Institutes of Health should be doing. The increasing brazen and emotional-laden ad campaigns by anti-smoking zealots seem to have infected the NIH and NCI with an attitude of “anything goes.” They can play that way if they choose, but only at the cost of their institutional credibility.
P.S. As I point out in my book, the effects of smoking on smell function are not as clear-cut as most people assume. For perspective, consider this statement by the JAMA authors: “It should be noted that the magnitude of the adverse effects of smoking on olfactory function is not large compared with the effects of such variables as age and sex.”
The study discussed here is “Dose-related effects of cigarette smoking on olfactory function,” by Richard E. Frye, Brian S. Schwartz & Richard L. Doty. JAMA 263:1233-1236, 1990.