If you follow a vegetarian diet are there any health side-effects?

All the vegetarians I have known seem to be very healthy people, because they still eat eggs and dairy products, and also lentils and nuts. Vegans can suffer symptoms of malnutrition, because of the lack of animal proteins and fats. Humans can survive on an amazing variety of diets, but we must have some animal products. You only have to look at our teeth to see that we are an omnivorous organism.