I think it depends if you like vegetables or not. I’m a vegetarian because I don’t like the taste of meat (and to a lesser degree I don’t like the idea of eating baby animals i.e. veal, lamb etc) I love vegetables but also like Quorn and tofu etc, so I get all the vitamins and nutrients that I need without supplements. My sister however, is a vegetarian that isn’t keen on vegetables. She quit meat purely because she doesn’t believe in killing animals and likes anything meat flavoured. She has to take vitamins to keep her in good health.