Gosh, there is tons of great info out there--it can be hard to know where to begin.
A wonderful online resource is The Vegetarian Resource Group (
www.vrg.org). It is a reputable organization run by registered dieticians. Its site has a ton of online nutritional information and recipies, as well as a bookstore through which you can order cookbooks. I highly recommend that you spend some time there!

They have a page about protein (
http://www.vrg.org/nutrition/protein.htm) as well as one about calcium (
http://www.vrg.org/nutrition/calcium.htm).
I find that negative attitudes about veg*nism are either based 1) on ignorance about nutrition or 2) the feeling of personal discomfort that many omnivores feel about their own dietary choices that surface when they meet someone who has chosen a different path. Which is the real issue with the people in your life?
I have found that the easiest way to allay concerns about veg*n nutrition is to give them a copy of the position statement of the American Dietetic Association/Dieticians of Canada (the most expert experts out there!) on vegetarian diets.
Their position is (in part):
Quote:
It is the position of the American Dietetic Association and Dietitians of Canada that appropriately planned vegetarian diets are healthful, nutritionally adequate, and provide health benefits in the prevention and treatment of certain diseases....
Well-planned vegan and other types of vegetarian diets are appropriate for all stages of the life cycle, including during pregnancy, lactation, infancy, childhood, and adolescence. Vegetarian diets offer a number of nutritional benefits, including lower levels of saturated fat, cholesterol, and animal protein as well as higher levels of carbohydrates, fiber, magnesium, potassium, folate, and antioxidants such as vitamins C and E and phytochemicals. Vegetarians have been reported to have lower body mass indices than nonvegetarians, as well as lower rates of death from ischemic heart disease; vegetarians also show lower blood cholesterol levels; lower blood pressure; and lower rates of hypertension, type 2 diabetes, and prostate and colon cancer.
The paper also notes that vegetarian diets have been given the stamp of approval by both the U.S. and Canadian government, FWIW.
The HTML version of the paper is at
http://www.eatright.org/Public/Gover...s/92_17084.cfm. The PDF version is at
http://www.eatright.org/Member/Files/veg.pdf.
Give the paper (or the link to the paper) to the people giving you a hard time, ask them to read it. Invite them to discuss any concerns they may have about your health AFTER THEY HAVE READ THE PAPER. If their negative attitude is truly based on health concerns, then they should stop bugging you after they read about how a vegetarian diet is typically more healthy than the standard American diet. (This paper is valuable for veg*ns to read, as well, as it contains some of the best nutritional information out there, and synthesizes the research.)
But if their problem with vegetarianism not related to nutrition, they may still get on your case with all sorts of "What if..." questions and philsophical debates. The best defense against those sorts of attacks is to know why you are vegetarian, educate yourself, and to stand firm in your beliefs.
Good luck, and welcome to the veg club!
