Sorry, I beg to differ.

B12. There is nothing in the plant world that has currently been proven conclusively to contain ACTIVE B12.

Aloe vera, seaweed/algae/spirulina and yeast supplements — they will tell you they contain B12 but they don’t tell you is that it’s analogue (inactive) which is a double whammy for people deficient with B12 because it blocks the uptake of active B12 yet will still appear in serum to skew levels when tested. Most health food stores and health food sites do not understand that these B12 analogues will block the B12 receptors, meaning you won’t absorb any B12. Serum B12 will remain high because the serum B12 test includes B12 analogues in the result, masking any active B12 deficiency.

Q: Is there a plant-based alternative for every vitamin and nutrient that animal-based products provide?

A: NOT FOR B12. You have to supplement with synthetic sources or B12 fortified foods.

Some reading:
PSEUDOVITAMIN B12,
VITAMIN B12 FOR VEGANS AND VEGETARIANS
WHY IS B12 SO IMPORTANT