Diets that exclude meat are associated with lower intakes of several B vitamins, including B2 (riboflavin), B3 (niacin), and B12 (cyanocobalamin). Notably, chlorella is a good source of vitamin B12 and may contain up to 400 micrograms of B12 per 100 grams of chlorella, depending on the source and the growing conditions; to put this in context, 400 micrograms of vitamin B12 is almost 200% of the recommended daily amount of B12 for adults.[1] For this reason, chlorella is often consumed as a plant-based source of vitamin B12 (and other B vitamins) by vegans and vegetarians.
Vegans with a vitamin B12 deficiency who supplemented with 9 grams of chlorella per day for 60 days reduced their levels of serum methylmalonic acid (an index of B12 deficiency) and homocysteine and increased their serum B12.[2]. In one cross-sectional study, vegans who reported consuming chlorella and/or nori (seaweed sheets made from a type of purple algae that also contains vitamin B12)[3] had serum levels of vitamin B12 almost twice as high as those not consuming these foods.[4]