From what I understand there are a number of possible reasons why someone chooses to become a vegetarian. One reason often cited is the health benefits one might enjoy from a diet when meat and sometimes dairy products is excluded.
According to a new study by a university in Austria (read the story here), vegetarians typically drink less alcohol, smoke less, and have a more active lifestyle but... The study also found that vegetarians suffer more from allergies, have more heart attacks, and develop more cancers.
The study showed that Austrians that adhered to a vegetarian diet have more health problems including mental health problems.
As with all studies, read and analyse with caution