Jennifer:
I do not believe vegetarianism is a healthy state for most people. I was one for years and years, was considered healthy, ate well, and got lots of nutrition, but it seriously hurt my health in the long run.
the B12 question is an excellent one. it is more than that, though. what about the tryptophans your body needs for mental health as well? it is very hard to keep it up on a vegetarian diet. if you happen to be someone whose brain is more sensitive to these subtleties, then you need to extra cautious or you might develop depression, etc.
when you are making this decision, then you should also consider reading some opposite info on diet than the standard, mainstream info. read Sally Fallon's NOURISHING TRADITIONS. it is an excellent nutritional treatise as well as cookbook. also, check out THE MOOD CURE by Julia Ross to investigate the effect all the vitamins and amino acids have on the brain. be very careful and be very smart. also, consider (and loosely) EAT FOR YOUR BLOOD TYPE. this book takes into consideration how each of us has a unique make up, and food needs, due to our ethnicity. did you know that 30% of those with a celtic background have problems with wheat / gluten? while a vegetarian diet is lovely, and peaceful, and you definitely are thinner, it may not be the healthiest for all people.
i was a vegetarian years ago for spiritual reasons. my health couldn't tolerate it more than 13 years. that was me, and my body type. NOT how I ate, as some people love to suggest. it is sort of like a diabetic eating sugar. sorry, can't be done. and vegetarianism is not for everyone, and can have long term detrimental effects for some people.
in terms of religious reasons, if you have any desire to consider the Christian point of view, most Christians today are one of the members of do-it-yourself churches, read and "know" on your own, or of one of the standard denominations that have deviated from the tradition. And, this explains all the confusion out there in Christian-land. please study the fasting of the first church, the Eastern Orthodox Church. Historically, it is a little known fact in our country that this was the church first established by the Apostles. in line with this, we follow a 2000 year TRADITION of worship. and part of that tradition is a lot of fasting throughout the year. these fasts are vegan in nature, EXCEPT that shellfish was always allowed, and the rest of the year we are allowed the meat. this is how it was always done. it was a form of abstinence from things of the earth and lightening the mind a bit, at the same time knowing the body was suffering deprivation, though it could act as a cleanse.it was designed to bring us closer to God. if you have any desire to find out more about this tradition of fasting in the church, let me know.
not trying to preach to anyone here, and hopefully i didn't offend anyone here. i really do respect everyone's views. since someone mentioned the bible and fasting i of course had to thrown in my 2 cents worth.