Treatment for nail-biting

One of the oldest treatments for nail-biting is to put a bitter tasting substance on one’s fingers. Aloe vera was the substance used when I first heard about the treatment, but other bitter ingredients are now commonly used. Leaving aside the question of whether or not the treament is appropriate or efficacious, one significant disadvantage of most of the bitter substances is that they are easily transferred from fingers to food. If you pick up a sandwich in fingers painted with bitter aloe, for example, your sandwich is likely to be less than appetizing.

One possible solution to the transfer problem might be admix the bittering agent with starch, or to find a way of binding it to starch. The intention would be to produce a substance which sticks tenaciously to one’s fingers but is degraded by the amylase that is present in human saliva. If one put one’s fingers in one’s mouth, the bittering agent would be released, but in the absence of amylase, the stuff would stick to one’s fingers and not to a sandwich.

The method would not be perfect because amylases are present in some foods as well as in saliva. There are some fruits, for instance, which produce amylase during their ripening; but it might even be possible to find a polysaccharide that is degraded by salivary amylase and not by other amylases.

Contributors: Mark R. Diamond