Unripe ackee has high levels of a toxin called hypoglycin A, which can be poisonous to humans. The FDA banned importing raw ackee in 1973 because of that–a ban still in place today. However, when ackee is ripe, it doesn’t pose a threat to humans and is a real delicacy. Rest assured, the ackee you can find in the U.S. is usually canned, and the FDA has investigated it thoroughly and considered cooked ripe ackee totally safe.