Ex-smokers might actually experience crack withdrawal symptoms (even though they never consciously ingested any) since it's one of the ingredients inserted in cigarettes in order to make them more addictive. Also added are extra nicotine, sugar, and caffeine to tobacco that way if a smoker has a particular area of weakness then it only requires one of these substances to get them hooked.
The same thing is happening with Starbucks beverages where glutamates are added to them to create addictions.
So anyone who has been regularly consuming these products may very well experience symptoms of withdrawal related to these addictive ingredients since some are much more susceptible to the effects than others. Just the same way that some are more prone to the effects of certain types of pollens in the air and others have no response.