It is synthesized in the lab but can be found in nature, like pretty much any other non-extracted DSHEA-compliant ingredient.
This topic always amused me. Black holes are "natural". Certain poisons are "natural". What makes "natural" better than "synthetic"? Are humans not natural beings with intelligence who make a product with reactions that occur naturally derived and created with our cleverness? The idea of a natural product is one of the biggest marketing ploys ever lol