How to strike a balance?

As I cycled home from work today, I mused over Paul’s blog entry about vegetarianism.  (Almost 10 miles of road to cover at my rate of speed leaves plenty of time for musing.)  I accept that meat-eating is not necessarily a good option - it’s hugely inefficient (in terms of calorific input required for every calorie of output), often inhumane, and rather enormously polluting (methane, anyone?).  However, in my comment to the entry, I made reference to two difficulties that I have with or can foresee about vegetarianism.

1.) Health.  To me, humans are meant to be omnivores; we evolved that way and it is difficult to ensure that one’s body gets all the nutrients it needs on a vegetarian diet.
2.) Food miles and seasonality.  I didn’t mention this directly in my comment, but it stands to reason that, if it is environmentally unfriendly for me to travel by air halfway around the world, then it is equally unfriendly for a tomato to do so.  Similarly unfriendly production might include hothouse tomatoes in January in, say, Wisconsin, or wherever.  Local, seasonal food has recently become something of a passion for me, and in my comment I posited that locally- and ethically-produced meat was about the only way to mitigate some of the ills of meat-eating. 

I still think that’s the case - if I’m going to eat meat (or dairy), then as much as possible I should consume local, humane products.  The real question that I have is this:

Is it possible to satisfy all three of these requirement - vegetarianism, healthy eating, and local, seasonal food - at once? 

For instance, some big staples of the vegetarian diet are legumes - beanspeaselentilspeanuts.  Thanks to the proliferation of the soya industry - feeding all those cows has had a good side effect, in this case - it is probably possible to get edamame produced in my home country.  But I honestly have no idea if I could get American peanuts.  And in any case, is food shipped thousands of miles - within the US - really “local”?  And my emphasis on seasonal food puts paid to having most fruits in many places in the middle of winter.  (That last isn’t strictly a problem related to vegetarianism, but I’m guessing everyone can agree that even potatoes can get a little old after several weeks of consuming only potatoes.)

I don’t really have any solution to any of this, obviously, and I would welcome anyone’s thoughts on the subject.