The ugly, the bad, and the risky: adverse effects, drug interactions and risks

The ugly, the bad and the risky: adverse effects, drug interactions and risks

Although seaweed and its constituents have a promising drug R&D period ahead of them, there are noted adverse/side-effects.  Studies have associated seaweed with the following adverse effects: iodine poisoning (NaturalStandard, 2009); hypothyroidism (Miyai, Tokushige & Kondo, 2008; Crawford et al, 2010); thyrotoxicosis (Bocanegra et al, 2009); organic dust toxic syndrome for external seaweed uses (Holm, Johannesson, Toren & Dahlman-Hoglund, 2009); and high platelet aggregation via high concentrations of fucoidan (de Azevedo et al, 2009).  Of course, it is equally fair to note that side-effects may be due to excessive dosage.

Noted and potential drug (Rx) interactions include: Fucoidan and heparin/anti-coagulants (Zhu et al, 2010); antithyroid drugs such as methenamine mandelate or methimazole; anticoagulant/anti-platelet drugs such as aspirin, warfarin or heparin (NLM/NIH, 2010).  Herbal medication interactions include anti-clotting supplements, such as clove, feverfew and Panax ginseng (NLM/NIH, 2010).

There are cautions to usage of seaweed supplements, pills, and/or extracts.  Dosage and recommended intake varies by species and manufacturing. Pregnant women are cautioned not to take seaweed as an iodine supplement due to lacking purity criteria (Zimmerman & Delange, 2004).  Other cautions include: trace chemicals/heavy metals, e.g. arsenic (Zimmerman & Delange, 2004); infertility; increased thyroid cancer risk (NLM/NIH, 2010); and risk of metabolic syndrome (Shin et al, 2009).