I'm really surprised at the lack of publicity surrounding the link between alfalfa sprouts and lupus. I just did a quick PubMed search of "lupus alfalfa sprouts" and found there was actually a bit of literature to back up the claim. Apparently, alfalfa contains a non-native amino acid called L-canavanine, which structurally resembles the native amino acid L-arginine and is often incorporated into proteins its place, producing defects in the folding patterns and function.
L-canavanine L-arginine
Just thought you should know. And, I now feel be better prepared to defend my position if the person behind the counter at Bruegger's ever calls me out on hating sprouts again.