Annatto, palm, rice bran: a field guide to tocotrienol sources

Three plants supply most of the world’s tocotrienols, and each gives a different isomer mix.

Annatto seeds give mostly delta-tocotrienol and no tocopherol. Palm fruit gives a balanced mix of alpha- and gamma-tocotrienol with some tocopherol. Rice bran is about half tocotrienol.

Because isomers behave differently, the source used in a study matters when comparing results.