Fucoidan, a sulfated carbohydrate rich in fucose and derived from brown seaweed and echinoderms, demonstrates antiviral properties against viruses including herpes simplex. Fucoidan also exhibits direct antiviral activity against a range of influenza viruses; previous research indicates it blocks viral attachment, entry, and replication. In this blog, I would like to share the following study with you, “Oral Fucoidan Attenuates Lung Pathology and Clinical Signs in a Severe Influenza A Mouse Model” by Claire Richards et al. This study examined the effectiveness of oral wakame fucoidan extracts (3.52 mg and 7.04 mg, equivalent to 1 or 2 g daily human dose) with varying molecular weights, in treating or preventing influenza in mice.

First, in a therapeutic model, wakame-derived fucoidan (UPF) was orally administered at a dose of 3.52 mg per day. The macroscopic lesions (clotting) in the lungs were significantly reduced compared to the control group. In addition to the previously mentioned findings, a noteworthy yet subtle decrease in the macroscopic lung pathology score, specifically the “lung consolidation” score, was observed in the animals treated with UPF following the completion of treatment when compared to the untreated control group, as visually depicted in Figure 1.

As a preventative measure, a dietary supplement containing UPF was administered three days before the infection. Following infection with H1N1 (PR8) influenza A, untreated mice maintained their body weight until day 2 post-infection. Beginning on day 3, weight loss was observed, as expected in this model, and continued to decrease throughout infection. Animals receiving 3.52 mg/day and 7.04 mg/day UPF showed similar weight loss compared to baseline weight beginning on day 3 post-infection and continued to decrease at a similar rate to that observed in untreated animals. In untreated animals, clinical signs were observed starting from day 3 post-infection. In all animals, the severity of clinical signs increased throughout the infection. A similar disease profile was observed in UPF-treated animals receiving lower-dose treatments. A significant reduction was observed at the higher dose of 7.04 mg/day on days 5 and 7 post-infection.

Lung coagulation scores were significantly lower in animals receiving a high dose of UPF (7.04 mg/day) than in those receiving a low dose (3.52 mg/day) or no treatment at all, as illustrated in Figure 2a. However, lung weights were similar in all three groups (Figure 2b).

In 96-well plates containing MDCK cells, triplicate titrations of lung homogenates from individual animals were performed, beginning with a 10−1 dilution and proceeding in full log dilutions to encompass a comprehensive range of concentrations. TCID50 values ​​were calculated for each sample and group means were calculated with SEM (n = 5). The mean TCID50 values ​​for animals receiving high dose UPF were slightly, but not significantly, reduced.

Further analysis by MTT staining showed a slight but non-significant decrease in cell viability in the lungs of animals receiving UPF treatment.

This study, using a BALB/c mouse model of severe H1N1 (PR8) influenza, concludes that concurrent oral administration of fucoidan from Undaria pinnatifida resulted in a significant reduction of the visible lung damage, manifesting as consolidation in the lungs. When fucoidan was included in the feed supplement 3 days before infection, both clinical signs of influenza and gross lung lesions were reduced in a dose-dependent manner. Substantial reductions in clinical scores and lung consolidation only became apparent with the administration of significantly higher doses, comparable to a daily human dosage of about two grams. Although viral titers were reduced, this was not significant, and suppression of viral load in the intestine rather than the lung mucosa may have led to reduced clinical symptoms.

Hence, the reduction in symptoms and lung consolidation in this study indicates the potential usefulness of this type of edible wakame fucoidan as a dietary supplement in the management of acute viral respiratory infections. The potential for higher fucoidan doses to further reduce symptoms warrants further investigation.

Source: Front Pharmacol. 2023 May 30;14:1164333. doi: 10.3389/fphar.2023.1164333