Seaweed
Seaweed or macroalgae refers to several species of macroscopic, multicellular, marine algae. The term includes some types of red, brown, and green macroalgae. Marine algae species such as kelps provide essential nursery habitat for fisheries and other marine species and thus protect food sources; ocean algae species from seaweeds to planktons play a vital role in carbon capture, producing up to 90 percent of the planet's oxygen. Understanding these roles provides guiding principles for conservation and sustainable use of seaweeds to take precedence over industrial exploitation. Mechanical dredging of kelp, for instance, destroys the resource and dependent fisheries. Certain species of seaweed are valuable for nutrition, biomedicine, bioremediation, and other uses.
Nori
Raw seaweed is 85% water, 6% protein, 5% carbohydrates, and has negligible fat (table). In a 100 gram reference amount, seaweed is a rich source (20% or more of the Daily Value, DV) of vitamin A, vitamin C, riboflavin, and folate (table). Seaweed is a moderate source (less than 20% DV) of niacin, iron, and zinc. Seaweed has a high content of iodine, providing a substantial amount in just one gram. A 2014 study reported that dried purple laver ("nori") contains vitamin B12 in sufficient quantities to meet the RDA requirement (Vitamin B12 content: 77.6 μg /100 g dry weight).