I'm not sure if I understand your questions, but unless a beer is 'fortified' with omega-3 fats, somehow, omega-3 fats are not going to be naturally occuring in beer.
Hope that makes sense. To reiterate, beer is not a source of omega-3s unless the beer manufacturer goes out of it way to add the omega-3s post production. And to me, that would make no sense, it would be an unpleasant flavor combination.