Oh I remember now I was actually looking at spirulina for omega 3.

Seemed hard to find numbers, but one source said 331mg of EPA per gram of Spirulina platensis (https://www.ripublication.com/ijac16/ijacv12n4_05.pdf).

Was considering what it would be like to eat like 6 grams of spirulina for 2g of EPA, versus that in one teaspoon of fish oil (high EPA type).

But got stuck on the B12 blocking stuff. I wonder if your point is true that there's enough redundancy it doesn't matter. It would be nice if it was easier/cheaper to get bloodwork to do some experiments with this kind of stuff.