Which statement about sea algae such as spirulina is true?

• A. They contain vitamin B12 that is about 50% available
• B. They contain no vitamin B12
• C. They are the richest source of vitamin B12
• D. They replace animal sources

Answer: (A)

Vitamin B12 from non-animal sources can be limited in both amount and usability. Spirulina does contain vitamin B12, but much of what’s present is in forms that aren’t usable by humans. The portion that is in a form we can absorb is not large, and studies have estimated that about half of the B12 in spirulina can be absorbed in some cases. This partial, not total, availability is why spirulina is not considered a dependable, long-term sole source of B12.

So, the statement aligns with the idea that there is some usable B12 in spirulina, roughly around 50% of what’s present, rather than none or a guaranteed, abundant supply. It also clarifies why spirulina cannot replace animal sources for B12.