Tuesday, May 24, 2022

Population Evidence For & Against Menthol Addictiveness


Last week I reviewed the FDA’s evidence concerning menthol’s possible role in furthering addiction, as discussed in the agency’s proposed menthol ban.  I noted that the FDA rationale “is primarily based on nicotine and menthol experiments on rats and mice, plus laboratory tests on tissue samples.  The FDA presents no evidence for menthol’s effects on actual smokers.”

One individual responded to my post by arguing that evidence shows that menthol can enhance addictiveness in humans; they provided a link to a single study.

There is, in fact, considerable population-based evidence of the effects of menthol smoking on addiction in humans, but the FDA failed to cite any of that, likely because the evidence is entirely contradictory.  While some studies show that menthol enhances addictiveness, other studies indicate the opposite.  A single study sometimes offers both positive and negative findings.

The FDA conducted its own review (available here) of the literature on this subject, spanning the period 1980 to April 30, 2021.  In its proposed ban, the FDA published these conclusions:

“The weight of evidence supports that the sensory effects of menthol contribute to positive smoking experiences that facilitate repeated use. Evidence also supports that menthol in
cigarettes is associated with progression to regular cigarette smoking in youth and young adults and greater dependence in youth. However, evidence is not sufficient to support a conclusion of an association of menthol in cigarettes with dependence among adults due to inconsistent findings.  Similarly, evidence is not sufficient to support a conclusion of an association of menthol in cigarettes with altered smoking topography. In the case of cessation, the weight of evidence suggests that menthol in cigarettes is likely associated with reduced cessation success in the general population and is associated with reduced cessation success among Black cigarette smokers.”

Thus, even the FDA acknowledges the lack of convincing evidence to support an outright menthol ban.  While the agency points to effects in youth and young adults, smoking has almost disappeared among both groups (here and here). 

More mixed results have been published since the FDA’s April 2021 research cut-off, including a comprehensive review that found:

“Forty-three demographically adjusted studies (22 rated 'good', 20 rated 'fair', and one study rated 'poor' individual study quality) comparing menthol and non-menthol smokers were qualitatively synthesized across the following measures (study count; strength of evidence): duration of abstinence (2; low); quit attempts (15; insufficient); rate of abstinence/quitting (29; moderate); change in smoking quantity/frequency (5; insufficient); and, return to smoking/relapse (2; insufficient). Overall, the qualitative synthesis failed to show a consistent trend for an association between menthol cigarette use and smoking cessation across outcomes. Meta-analyses found no difference between menthol and non-menthol cigarette use and either quit attempts or abstinence.” (emphasis added)

The population evidence is clear: The addictive action of menthol remains ambiguous.

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