[brushfoot]

The ratio of Omega 6 to 3 needs to be below 4:1 to be a good source of Omega 3, and hemp hearts are at 3:1, so they're listed as a good source of Omega 3.

Flax seeds are even better just for Omega 3 at 1:3, but hemp hearts have other benefits, like more protein, which is why I called them out. That said, I eat a fair amount of flax seeds as well.

[cube2222]

Just to reiterate, both of those (hemp hearts and flaxseed) only contain ALA, while what you're generally looking for is EPA and DHA. TFA also explicitly mentions it's only talking about EPA.

This is not to say that they're unhealthy of course.

EDIT: see the sibling comment by code_biologist, it's much more comprehensive than what I've written.

[brushfoot]

Your body converts ALA into EPA and DHA, however, so plants are fine sources of both.