Unless you cut your nose off surgically first, how are you going to eat it? (That's what your question means, by the way.) Should you decide to do so, it would certainly be 'harmful' to your appearance!
I was told that my bogeys were bits of my brain dried up. For years I picked my nose and then kept the pickings in a cassette box. They went all dry and crispy.
I chose not to eat it cos then I was eating my own brain power and I'd get thick. You'll get thick alan too, don't do it.
There's a woman in the same nursing home as my grandmother. She picks her nose and eats the contents that she removes - she was 105 years old last week - so I suppose it may have qualities that make you almost immortal!!!
I would think it would have a negative effect. Not serious though. What do you think snot is all about? It and the hairs up your snout prevent all the dirt/dust and germs/bacteria etc... from entering your lungs. Therefore if you eat it, it will go directly into your body, which basically is opposite the whole point of your nose being a filter system