I cannot for the life of me find the quote you are referring to and I promise you that I'm trying as hard as can. Could you cite the speech where he made that claim?
He DID recently claim that African American unemployment is 51% - Politifact rates that as "mostly true", meaning sure, he is a politician and there's a bit of a spin on what he's saying, but the numbers are confirmed in hard research nonetheless. (It actually depends on whose research you read; Sanders got his numbers from a think tank known to be a little left wing. That doesn't necessarily mean that he's wrong or lying! It means you get to dispute the methodology of the study.)
I heard the interview clip on NPR and both NPR and FactCheck.org nailed him. And honestly, FactCheck.org is always calling him out. And if you look at his voting history, it does not match his rhetoric. I'm going to stick with the one candidate that during the GOP debate (if you could really call it a debate...and for the record, I'm Libertarian) didn't get a mention on the FactCheck post mortem: Rand Paul. To not get listed on a lies list is a good sign.