Gretings from Norfolk (UK)

We have two Burman cats, both very much loved, but they keep eating grass
and bringing back bile etc.  This has been happening more ferequently of
late - almost every day - though they appear healthy and very lively.

Can anybody comment on the frequency, is it too frequent, or is this fairly
normal.  Both cats are about 10 years old.
Any help much appreciated.
--
Richard.

"I have yet to see any problem, however complicated, which when looked at in
the right way, did not become still more complicated"
Poul Anderson