A survey of naturally occurring plant-derived food sources with high Vitamin B12 contents suggested that dried purple laver (nori, Porphyra yezoensis) is the most suitable Vitamin B12 source presently available for vegetarians.
The amount of total vitamin B12 in the dried purple laver was estimated to be 55 -59 mcg / 100 g dry weight. The purple laver contained 5 types of biologically active vitamin B12 compounds (cyano-, hydroxo-, sulfito-, adenosyl- and methylcobalamin), in which the vitamin B12 coenzymes (adenosyl- and methylcobalamin) comprised about 60 % of the total vitamin B12:
Dried purple laver also contains high levels of other nutrients that are lacking in vegetarian diets, such as iron and n-3 polyunsaturated fatty acids. Dried purple laver is a natural plant product and it is suitable for most people in various vegetarian groups.