COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which binds to angiotensin-converting enzyme 2 (ACE2) on the cell surface and downregulates ACE2, likely elevating the ratio of angiotensin-converting enzyme (ACE) to ACE2. The overreaction of the immune system, combined with the cytokine storm and ACE dominance, is purported to cause the condition of COVID-19 patients to deteriorate rapidly. Japan was one of the first countries affected by the COVID-19 pandemic, yet the number of deaths per 100000 population is much lower than in other Western countries. The reasons are likely multifactorial, but a contributing factor might be the traditional Japanese diet, which is rich in seaweeds. Various seaweeds, including Saccharina spp. (kombu), Undaria pinnatifida (wakame), and Porphyra spp. (nori), are among the major ingredients in traditional Japanese cuisine. Dietary seaweeds contain numerous components, including ACE inhibitory peptides, soluble dietary fibers (eg, fucoidan, porphyran), omega-3 fatty acids, fucoxanthin, fucosterol, vitamins D3 and B12, and phlorotannins. These components exert antioxidant, anti-inflammatory, and antiviral effects directly as well as indirectly through prebiotic effects. This review summarizes the pathophysiology of COVID-19 and examines the potential protective effects of dietary seaweeds against COVID-19.

Tamama K. Potential benefits of dietary seaweeds as protection against COVID-19. Nutr Rev. 2020 Dec 20:nuaa126. doi: 10.1093/nutrit/nuaa126. Epub ahead of print.

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