Crab and lobster are most commonly served baked, steamed, or in bisque. A 100g serving of crab contains 11.5μg of vitamin B12 (192% of the RDA), that is 15.4μg (257%RDA) per leg (134g). Lobster will provide 4.04μg(67% RDA) per 100g serving, or 6.59μg (110% RDA) in an average whole lobster (163g).