According to ARIN Who-Was they've had this ASN assigned and removed multiple times.
Created 11-20-2000 19111 NATURES-BOUN AS19111 NATURE-24
Registration Removed 12-12-2006
Created 01-04-2007 19111 NATURES-BOUN AS19111 NATURE-24
Registration Removed 07-14-2009
Created 07-22-2009 19111 NATURES-BOUN AS19111 NATURE-24
Modified 01-09-2012 19111 NATURES-BOUN AS19111 NATURE-24
Registration Removed 04-07-2015
Created 02-01-2016 19111 NBTY19111 AS19111 NATURE-24
Registration Removed 04-11-2017
I'm assuming this is due to non-payment each time.