Is alfalfa sprouts hazardous

Any food is hazardous if you eat too much of it.

Alfalfa seeds contain canavanine, an amino acid that is a variant of the more common lysine. When canavanine is eaten, it occasionally is used in proteins in place of lysine, resulting in aberrant proteins that don't function properly. It's therefore toxic.

However, by the time the seeds germinate, most of the canavanine is used up. There's still a small amount in the sprouts, but unless you're making alfalfa sprouts a significant portion of your overall diet, it's not likely to be enough to hurt you.