Re: Why are the taste buds of the elderly less sensitive than those of kids?

Dear Jake,
     You have asked an interesting question.  One reason why taste 
sensitivity may decline with age may be a simple decline in numbers of 
taste buds with aging--a 35% decline has been reported for aging rats (see 
the journal Radiation Research vol. 37,pp. 31-49, 1969 "Radiation and aging 
effect on taste bud structure & function" by A. D. Conger).  The reason for 
this age-associated decline is unclear.  One factor is that taste buds must 
receive nerve innervation for function:  if the nerves to a rat tongue are 
cut, taste buds rapidly disappear from the epithelium!  Also, metals such 
as zinc strongly affect taste function (see papers by Dr. R. I. Henkin, 
eg., Annals of Internal Medicine 71:791, 1969), probably by affecting the 
function of proteins in the oral cavity that influence taste function.  
Elderly people with dietary zinc deficiencies may complain of poor taste 
function and can be treated with dietary zinc supplements.  Finally, it's 
of some interest that the first taste receptor protein may finally have 
been identified this year (see the journal Cell, vol. 96, pp. 541-551, 1999 
"putative mammalian taste receptors:  a class of taste-specific GPCRs with 
distinct topographic selectivity" by Mark A. Hoon, et al--you could 
probably download a summary of this paper by looking at a Web site called 
Pubmed, organized by the National Library of Medicine in Bethesda, MD.