What are the disadvantages and advantages to a vegetarian diet?

Good to know: The big studies have not shown increased longevity or much protection from any of the common cancers or vascular diseases just from vegetarianism / veganism. These people do tend to have other healthy habits. I admire the moral statement against the cruelty of factory farming. If you do not supplement (b12, several others) you will ruin your health -- your physician can guide you.

A vegetarian diet: Is healthy. For more information, check out drmcdougall.Com and nutritionfacts.Org. Both cite lots of research on the benefits of a plant-based diet. Nutritionfacts.Org includes information on the effects of diet on numerous health issues. I don't know of any disadvantages to a vegetarian diet other than having to ignore food commercials on tv and look harder for suitable restaurants.

The only definite: problem is that unlike meat vegetables don't provide complete proteins, they lack certain amino acids, and you must selectively combine different plant products to receive adequate amounts of all required amino acids.