riddle with no answer ... do you know it?

[Doreen Rich]

Someone sent my mother this riddle but did not send the answer. Now, 
my mom thinks that I can find anything on my computer. I tried. I can 
not. Does anyone have a clue to the answer? It is said that 80% of 
small school children answered it and only 17% of all college 
children. (It also said that if I sent it to 10 people the answer 
would appear, but I know better than to believe that nonsense)

Help!!

Here is the riddle:

What is greater than God, More evil than the devil, The poor have it, 
the rich need it, And if you eat it, you'll die?

Thanks
Doreen