Supplements for Teenage Vegetarian?

I am a vegetarian since birth and now I'm 26 years old. I don't remember any regular vitamins that we take since we were kids. I think if the diet is balance well enough, we get all the vitamins in it. But since our soil is not that pure and is mixed with chemical, the vitamins we used to get from fruits and veggies is not that reliable anymore. Maybe eating organic fruits and vegetable will help and like I said maintain a healthy and balance lifestyle. So far I'm not a sickly person, I would even feel sickness in a year or two and I'm even premature because I was born 6 1/2 mos, but I survived because the doctor said my lungs is strong.