Arsenic speciation in a variety of seaweeds and associated food products

Seaweeds, or sea vegetables, are popularly consumed for their nutritional qualities and have been shown to have numerous health benefits to consumers being rich in a host of vitamins and minerals. A wide range of brown, red and green seaweeds are consumed globally with around 145 species known to be directly consumed by humans worldwide. It has been reported that several popularly consumed seaweed species, including Laminaria digitata, Alaria esculenta, and Hizikia fusiforme, possess the ability to accumulate elevated quantities of arsenic (As) in their tissues. Some studies have highlighted concerns relating to consumption of certain seaweed species due to their As content. The ability of seaweed to bioaccumulate high levels of As raises some concerns regarding their safety. There is evidence that elevated levels of As known in some particular species have the potential for biomagnification through successive marine food chains and ultimately onto higher trophic levels. This presents highly pertinent questions regarding the safety of seaweed consumption and its potential to contribute to increased dietary intake of As. New classes of As metabolites such as thiolated arsenicals are yet to be fully elucidated in terms of toxicity, but it is thought that these particular species may play an important role in As metabolism and toxicity. Similarly, much is yet to be fully understood regarding the formation pathway of methylated As and As_Sug. This review highlights the presence and speciation of arsenic in a variety of macroalgal food and associated products.