capistrano - want to environment variable to be set

I'm running centos on my server, and naturally, I'm using capistrano to
deploy rails.

I have a script, /etc/profile, that runs when I log in via ssh. It sets
a bunch of environment variables like PATH, and GEM_HOME.

However, when I run a command from capistrano, like

run "rake db:migrate"

it can't find rake, because /etc/profile is never run (and never sets
PATH), even though I'm using the same user as when I ssh in manually.

Any ideas how I can make sure /etc/profile is run before every
capistrano shell session?