I get those sometimes as well, particularly if I happen to eat a lot of meat in a day. I call them my "meat dreams".

I had never heard of the B-6/dream connection, but I found a study showing that pyridoxine (B-6) had a significant effect on dream salience, which included vividness, color, bizarreness, etc. I don't know if the results have since been duplicated though.

Ebben M, Lequerica A, Spielman A.,Effects of pyridoxine on dreaming: a preliminary study. Percept Mot Skills. 2002 Feb;94(1):135-40.