MENTHOL TITRATION: “once a smoker adapts to smoking a menthol product, the desire for menthol increases over time. A brand … will invariably increase its menthol level. Thus, once a brand becomes successful, its product will evolve in a manner that is not optimal for younger adult non-menthol smokers/switchers.”
http://tobaccocontrol.bmj.com/content/20/Suppl_2/ii12.full